Human Anatomy and Physiology Questions-Reviews.docx

CHAPTER QUESTIONS REVIEW EXERCISES Chapter Introduction to Human Anatomy and Physiology Part A Briefly describe the early development of knowledge about the human body Our earliest ancestors probably became curious about the body during illnesses and injuries At these times they visited shamans who relied on superstition and magic Throughout early time this curiosity lead to discoveries of the healing powers of certain herbs and potions especially to treat coughs headaches and other common problems Not until about years ago did these superstitious attitudes change and the body was looked at in the new light of modern science Experiments accurate observations and tried techniques rapidly expanded knowledge of the human body Greek and Latin words were used as a basis to describe body part locations and to explain their functions This formed the basis for anatomy and physiology Distinguish between the activities of anatomists and physiologists Anatomists deal with the structure morphology of the body parts This includes the shapes forms and placement of body organs and appendages Physiologists deal with the functions of body parts what the body parts do and how this is accomplished How does a biological structure s form determine its function Give an example The functional role will depend upon the manner in which the part is constructed The human hand with its long jointed fingers makes it possible for human beings to grasp things List and describe the ten characteristics of life Movement is the ability to self-initiate position changes of either the entire organism or a part of the organism externally from place to place and or internally such as in peristalsis Responsiveness refers to the ability of an organism to detect changes either within itself or the environment surrounding it and then react to these changes Growth generally refers to an increase in body size without important changes to its general shape Reproduction is the process of making a new organism as in parents producing offspring It also discusses the process whereby cells can produce others like themselves to take the place of damaged or destroyed cells Respiration refers to the process of obtaining oxygen using the obtained oxygen in release of energy from foods and removing waste gases that are produced in the process Digestion is the chemical change of ingested foods into simpler substances that can be taken in and used by body parts Absorption is the passage of digested substances through membranes Define metabolism The totality of chemical changes that occur within body parts List and describe five requirements of organisms Water the most abundant substance in the body is required for many metabolic processes It provides the environment for the metabolic processes to take place and then transports substances within the body It is also important in the process of regulating body temperature Food is the substances that provide the body with the necessary chemical to sustain life in addition to water These chemicals are used in a variety of ways by the body Oxygen which makes up about one-fifth of air is used in the process of releasing energy from food substances Heat a form of energy is a product of metabolic reactions The rate at which these reactions occur is partly governed by the amount of heat present Pressure is a state in which a force is applied to something Atmospheric pressure is an important role in breathing Hydrostatic pressure the pressure of fluid plays an important role in the circulatory system Explain how the idea of homeostasis relates to the five requirements you listed in item Homeostasis refers to the stable internal environment of an organism In human beings if the requirements listed above become unstable the body will react in certain ways to regain its stable internal environment An example would be sweating to help decrease body temperature Distinguish between heat and temperature Heat is a form of energy that is a product of metabolic reactions Temperature is the amount of heat that is present at any given time What are two types of pressures that may act upon organisms Atmospheric pressure is the pressure of the atmospheric air on the outside of an organism Hydrostatic pressure is the pressure exerted by a liquid on the outside of an organism How are body temperature blood pressure and blood glucose concentration controlled Homeostasis is maintained in each of these situations by a self-regulating control mechanism that can receive signals about changes away from the normal set points and cause reactions that return conditions to normal In what ways do homeostatic mechanisms act by negative feedback Homeostatic mechanisms detect changes away from the normal state This stimulates responses in the opposite directions which are called negative responses This process is called negative feedback How does the human body illustrate the levels of anatomical organization The basic unit of structure and function in the human body is the microscopic cell These cells organize into layers that have common functions These layers are called tissues These tissues then group together to form organs Groups of organs make up organ systems Groups of organ systems make up the organism which in this case is the human Distinguish between the axial and appendicular portions of the body Axial portion This consists of the head neck and trunk Appendicular portion This consists of the arms and the legs Distinguish between the dorsal and ventral body cavities and name the smaller cavities within each The dorsal cavity is located at the back of the organism It can further be subdivided into two parts the cranial cavity within the skull which houses the brain and the spinal cavity which contains the spinal cord and is surrounded by sections of the backbone vertebrae The ventral cavity is the front part of the organism It is subdivided into two parts a thoracic cavity which houses the lungs and heart and a abdominopelvic cavity which houses the stomach liver spleen gallbladder small and a large intestines urinary bladder and the internal reproductive organs What are the viscera The viscera are the organs found deep within a body cavity Where is the mediastinum The mediastinum is the region that separates the thoracic cavity into two compartments which contain the right and left lungs Describe the locations of the oral nasal orbital and middle ear cavities Oral cavity is the mouth area and contains the teeth and the tongue Nasal cavity is located within the nose and is divided into right and left portions by a nasal septum Air-filled sinuses are connected to the nasal cavity including the sphenoidal and frontal sinuses Orbital cavities contain the eyes and associated skeletal muscles and nerves Middle ear cavities are found inside the ear and contain the middle ear bones How does a parietal membrane differ from a visceral membrane A parietal membrane refers to a membrane that is attached to the wall and forms the lining of a cavity whereas a visceral membrane refers to a membrane that is deeper toward the interior and covers the internal organs contained within a cavity Name the major organ systems and describe the general functions of each Integumentary system It protects underlying tissues helps regulate body temperature houses a variety of sensory receptors and synthesizes certain products Skeletal system It provides frameworks and protective shields for softer tissues serves as attachments for muscles when body parts move It also has a role in blood cell production and storage of inorganic salts Muscular system It provides the forces that cause body movements They also maintain posture and are the main source of body heat Nervous system It provides the ability to detect changes that occur inside and outside the body It interprets the sensory impulses and what to do in response to these impulses It also plays a role in muscle contraction and gland secretions Endocrine system It secretes hormones that alter metabolism of a target tissue Cardiovascular system It pumps blood throughout the body The blood serves as a fluid for transporting gases nutrients hormones and wastes Lymphatic system It transports tissue fluid back to the bloodstream and carries certain fatty substances away from the digestive organs It also plays a role in immunity Digestive system It receives various food molecules from the outside and converts them into simpler ones that can be absorbed Respiratory system It provides for the intake and output of air and for the exchange of gases between blood and air Urinary system It removes various wastes from the blood and assists in maintaining the body s water electrolyte and acid-base balances Reproductive system It is responsible for the production of whole new organisms like itself List the major organs that comprise each organ system Integumentary system It consists of the skin and various accessory organs such as the hair nails sweat glands and sebaceous glands Skeletal system It consists of the bones ligaments and cartilages Muscular system It consists of the muscles Nervous system It consists of the brain spinal cord nerves and sense organs Endocrine system It consists of glands that secrete hormones Cardiovascular system It consists of the heart arteries veins capillaries and blood Lymphatic system It consists of the lymphatic vessels lymph fluid lymph nodes thymus gland and spleen Digestive system It consists of the mouth tongue teeth salivary glands pharynx esophagus stomach liver gallbladder pancreas small intestine and large intestine Respiratory system It consists of the nasal cavity pharynx larynx trachea bronchi and lungs Urinary system It consists of the kidneys ureters urinary bladder and urethra Reproductive system The male reproductive system consists of the scrotum testes epididymides vasa deferentia seminal vesicles prostate gland bulbourethral glands penis and urethra The female reproductive system consists of the ovaries uterine tubes uterus vagina clitoris and vulva In what body region did Judith R s injury occur Right hypochondriac region Part B Name the body cavity housing each of the following organs stomach abdominal heart thoracic brain cranial liver abdominal trachea thoracic rectum pelvic spinal cord vertebral esophagus thoracic spleen abdominal urinary bladder pelvic Write complete sentences using each of the following terms correctly superior The head is superior to the abdomen inferior The legs are inferior to the chest anterior The eyes are anterior to the brain posterior The brain is posterior to the eyes medial The nose is medial to the eyes lateral The ears are lateral to the eyes ipsilateral The spleen and descending colon are ipsilateral contralateral The spleen and gallbladder are contralateral proximal The elbow is proximal to the wrist distal The fingers are distal to the wrist superficial The epidermis is the superficial layer of the skin peripheral The nerves that branch from the brain and spinal cord are peripheral nerves deep The dermis is the deep layer of the skin Prepare a sketch of a human body and use lines to indicate each of the following sections sagittal transverse coronal See figure page Prepare a sketch of the abdominal area and indicate the location of each of the following regions epigastric umbilical hypogastric hypchondriac lumbar iliac See figure page Prepare a sketch of the abdominal area and indicate the location of each of the following regions right upper quadrant right lower quadrant left upper quadrant left lower quadrant See figure page Provide the common name for the region described by the following terms acromial point of shoulder antebrachial the forearm axillary the armpit buccal the cheek celiac the abdomen coxal the hip crural the leg femoral the thigh genital the reproductive organs gluteal the buttocks inguinal the depressed area of the abdominal wall near the thigh groin mental the chin occipital the lower back region of the head orbital the eye cavity otic the ear palmar the palm of the hand pectoral the chest pedal the foot perineal the region between the anus and external reproductive organs perineum plantar the sole of the foot popliteal the area behind the knee sacral the posterior region between the hipbones sternal the middle of the thorax anteriorly tarsal the instep of the foot umbilical the navel vertebral spinal column Chapter Chemical Basis of Life Distinguish between chemistry and biochemistry Chemistry is the study of the composition of substances and how they change Biochemistry is the chemistry of living organisms Define matter Matter is anything that has weight and takes up space Explain the relationship between elements and atoms An element is a basic substance that other things are composed from Each individual element is made up of tiny invisible particles called atoms The atom is the smallest complete unit of an element Define compound A compound is the product of two or more elements being combined List the four most abundant elements in the human body The four most abundant elements are hydrogen oxygen carbon and nitrogen Describe the major parts of an atom Each atom is composed of a central portion called a nucleus and one or more electrons that are in constant motion around the nucleus The nucleus contains one or more large particles called protons and can also contain one or more similarly-sized particles called neutrons Distinguish between protons and neutrons Protons carry a single positive electrical charge p Neutrons are uncharged and thus are electrically neutral n Explain why a complete atom is electrically neutral The electron carries a single negative electric charge The protons carry a single positive electric charge Neutrons carry no charge thereby making them electrically neutral The atom is electrically neutral because there is the exact same number of protons and electrons which effectively cancel each other out Distinguish between atomic number and atomic weight Atomic number represents the number of protons in an atom of a particular element Since atoms are electrically neutral it also tells you the number of electrons Atomic weight represents the number of protons plus the number of neutrons in an atom of a particular element Define isotope Isotopes are elements with the same atomic number but different atomic weights Define atomic radiation Atomic radiation is the energy or atomic fragments that are given off by unstable isotopes Describe how electrons are arranged within atoms The electrons of an atom are found in one or more shells around the nucleus The maximum number of electrons that each of the first three inner shells can hold is as follows First shell closest to the nucleus electrons Second shell electrons Third shell electrons Explain why some atoms are chemically inert An atom is chemically inert when the outermost electron shells are filled These atoms cannot form chemical bonds Distinguish between an ionic bond and a covalent bond An ionic bond electrovalent bond is formed when atoms gain or lose electrons A covalent bond forms when atoms share electrons Distinguish between a single covalent bond and a double covalent bond A single covalent bond occurs when atoms share one pair of electrons A double covalent bond occurs when atoms share two pairs of electrons Explain the relationship between molecules and compounds A molecule is formed when two or more atoms of the same element bond together A compound is formed when two or more elements of different atoms combine Distinguish between a molecular formula and a structural formula A molecular formula consists of the symbols of the elements in the molecule together with numbers to indicate how many atoms of each element are present It is essentially the recipe for that particular molecule or compound A structural formula is drawn to represent how atoms are joined and arranged in various molecules This is essentially the blueprint of how they fit together Describe three major types of chemical reactions A synthesis reaction occurs when two or more reactants bond together to make a new and more complex product It can be symbolized as follows A B AB A decomposition reaction occurs when a more complex substance is broken apart into smaller simple substances It can be symbolized as follows AB A B An exchange reaction occurs when parts of two molecules change positions It can be symbolized as follows AB CD AD CB Explain what is meant by reversible reaction A reversible reaction is one in which the end product or products of the reaction can changed back to the reactant or reactants that originally underwent the reaction A B AB Define catalyst A catalyst is a particular atom or molecule that can change the rate of a reaction without being consumed or changed by the reaction Define acid base salt and electrolyte An electrolyte is a substance that releases ions in water An acid is an electrolyte that releases hydrogen ions H in water A base is an electrolyte that releases ions that can combine with hydrogen ions These are usually hydroxyl ions OH- A salt is the product formed by the reactions of acids and bases Explain what pH measures pH measures the concentration of hydrogen ions found in substances Distinguish between organic and inorganic substances An organic substance contains both carbon and hydrogen atoms An inorganic substance lacks carbon atoms Describe the roles played by water and by oxygen in the human body Water is the most abundant substance in the human body It is a major component of blood and other body fluids It is an important solvent It also has an important role in the transportation of chemicals in the body Additionally water can absorb and transport heat Oxygen is used by cellular organelles in the process of releasing energy from glucose and certain other molecules The resultant energy is used to drive the cell s metabolic activities List several ions that cells require and describe their general functions Sodium Na chlorine Cl- potassium K calcium Ca magnesium Mg phosphate PO - carbonate CO - bicarbonate HCO - and sulfate SO - are the ions that play important roles in metabolic processes These processes include maintenance of proper water concentrations and nerve functions in body fluids pH blood clotting bone development energy transfer within cells and muscle function Define electrolyte balance Electrolyte balance is the condition where the electrolytes are present in certain concentrations both inside and outside cells to maintain homeostasis Describe the general characteristics of carbohydrates Carbohydrates supply much of the energy for the cells They supply building materials for certain cell structures and are often stored as reserve energy These molecules contain atoms of carbon hydrogen and oxygen Carbohydrates usually have twice as many hydrogen as oxygen atoms The carbon atoms are joined in chains that vary in length with the specific kinds of carbohydrates Distinguish between simple and complex carbohydrates Simple carbohydrates are the six-carbon sugars known as simple sugars Complex carbohydrates are formed when a number of simple sugar molecules are bound together to form molecules of varying size Describe the general characteristics of lipids Lipids are organic substances that are insoluble in water but soluble in certain organic solvents They supply more energy gram for gram than carbohydrates They contain carbon hydrogen and oxygen Lipids contain a much smaller proportion of oxygen than carbohydrates Distinguish between saturated and unsaturated fats A saturated fat contains no double bonds between carbon atoms An unsaturated fat contains one or more double bonds between carbon atoms Describe the general characteristics of proteins Proteins can be used as structural materials energy sources hormones and receptors on cell surfaces that are specialized to bond to particular kinds of molecules Others act as antibodies against foreign substances that can enter the body Still others act as enzymes in metabolic processes Proteins contain atoms of carbon hydrogen and oxygen In addition they always contain nitrogen atoms and sometimes contain sulfur atoms as well Describe the function of an enzyme An enzyme is a molecule that acts as a catalyst in living systems That is it speeds specific chemical reactions without being consumed or changed in the process Explain how protein molecules may become denatured When protein molecules lose their unique shape and become disorganized they become denatured This can be a result of exposure to excessive heat radiation electricity or various chemicals When they become denatured it is a permanent change and they are therefore nonfunctional Describe the general characteristics of nucleic acids Nucleic acid molecules are generally very large and complex They contain atoms of carbon hydrogen oxygen nitrogen and phosphorus These are bound into building blocks called nucleotides Explain the general functions of nucleic acids These control all cell activities They store information that is used by cell parts to construct specific kinds of protein molecules including enzymes Chapter Cells Use specific examples to illustrate how cells vary in size Nerve cells have long threadlike extensions to transmit impulses Epithelial cells are smaller and flattened for gas exchange Muscle cells are slender and rodlike Describe how the shapes of nerve epithelial and muscle cells are well suited to their functions Nerve cells are long with threadlike extensions that can be used to transmit motor or sensory information Muscle cells are slender and rodlike which contract to move parts of the body Epithelial cells specifically simple squamous are thin and flattened for gas exchange Name the major components of a cell and describe how they interact The two major components are the nucleus and the cytoplasm The nucleus is the innermost part and controls the overall activities of a cell The cytoplasm is a mass of fluid that surrounds the nucleus and is enclosed by the cell membrane It holds the organelles Discuss the structure and functions of a cell membrane The basic structure of the cell membrane consists of a phospholipid bilayer It contains embedded protein molecules It functions to keep the inner portion of the cell intact It controls the entrance and exit of substances How do cilia flagella and cell adhesion molecules move cells Cilia small hair like projections that occur in groups move together in a uniform wavelike motion This is used to propel substances along to a certain destination An example is the uterine tube where the cilia move the egg from the ovary to the uterus Flagella which occur singularly have a whiplike motion to propel the object forward An example is the sperm cell moving up the vagina toward the cervix Cell adhesion molecules CAMS occur on the cell membrane The resulting interactions can slow the cell and allow it to move in certain ways See Figure page Distinguish between organelles and inclusions An organelle is a structure within the cytoplasm that has a specific function Inclusions are masses of lifeless chemicals such as pigments or glycogen Define selectively permeable Selectively permeable means that the cell membrane allows some substances to pass through easily while excluding other substances Describe the chemical structure of a membrane The basic framework consists of a phospholipid bilayer with embedded proteins throughout Explain how the structure of a cell membrane determines which types of substances it is permeable to As the cell membrane is comprised chiefly of fatty acid portions of the phospholipid molecule it allows substances that are soluble in lipids to pass through easily It is impermeable to water soluble molecules Explain the function of membrane proteins The functions of membrane proteins include acting as a receptor to combine with a specific substance such as a hormone while some form narrow passageways or channels through which various molecules and ions can cross the cell membrane Others function as enzymes in signal transduction Describe three kinds of intercellular junctions These include Tight junctions The membranes of adjacent cells converge and fuse The area of fusion surrounds the cell like a belt This then closes the junction between cells These are the types of junction found in the lining of the digestive tract Desmosome This is where rivets or spot welds are placed between adjacent skin cells Gap junctions This is where tubular channels interconnect the membranes of certain cells Describe the structures and functions of each of the following endoplasmic reticulum It is composed of membrane-bound flattened sacs and elongated canals These are interconnected and communicate with the cell membrane nuclear envelope and certain cytoplasmic organelles Two types of endoplasmic reticulum are found Smooth endoplasmic reticulum lacks ribosomes embedded into the membrane These are found in rough endoplasmic reticulum It functions as a tubular communication system It also functions in the production of proteins ribosome These are composed of protein and RNA molecules These function in the synthesis of proteins Golgi apparatus Located near the nucleus it consists of a stack of about six flattened membranous sacs whose membranes are continuous with the endoplasmic reticulum This functions to refine and package the proteins synthesized by the ribosomes associated with the endoplasmic reticulum mitochondrion These are elongated fluid-filled sacs The membrane surrounding a mitochondrion has an inner and outer layer The inner layer is folded extensively to form partitions called cristae In the cristae are enzymes that control some of the chemical reactions by which energy is released from glucose and other organic molecules The cristae function in transforming this energy into a chemical form that is usable by various cell parts lysosome These appear as tiny membranous sacs that contain powerful enzymes that are capable of breaking down molecules of nutrient or foreign particles that enter cells These also function in the destruction of worn cellular parts peroxisome These are membranous sacs resembling lysosomes in size and shape They contain enzymes called peroxidases which catalyze metabolic reactions that release hydrogen peroxide H O as a byproduct These also contain catalase which is an enzyme that decomposes hydrogen peroxide that that is toxic to cells cilium These contain microtubules arranged in distinct cylindrical patterns Cilia occur in large numbers on the free surface of some epithelial cells Each is a tiny hairlike structure about microns long These are arranged in precise patterns and have coordinated wavelike movement flagellum There is usually one to a cell It is longer than a cilium but is structurally put together the same way This has an undulating whip like motion The flagellum is generally used for movement centrosome Located in the cytoplasm near the Golgi apparatus and nucleus these are nonmembranous and consist of two hollow cylinders called centrioles These function in reproduction by aiding in the distribution of chromosomes to the newly forming cells vesicle These are membranous sacs formed by an action of the cell membrane in which a portion of the membrane folds inward and pinches off These play a role in phagocytosis and pinocytosis microfilament Microfilaments are tiny rods of the protein actin arranged in meshworks or bundles They cause various kinds of cellular movements microtubule Microtubules are long slender tubes with diameters two or three times greater than a microfilament These are composed of the globular protein tubulin These are usually somewhat rigid forming the cytoskeleton which helps maintain the shape of the cell Describe the structure of the nucleus and the functions of its contents The nucleus is a cellular organelle that is usually located near the center of the cell It is a relatively large spherical structure enclosed in a double bilayered nuclear envelope consisting of inner and outer membranes This allows various substances to move between the nucleus and the cytoplasm The nucleolus is a small dense body composed largely of RNA and protein It assists in the production of ribosomes Chromatin consists of loosely coiled fibers composed of DNA molecules and protein that contain information for synthesizing proteins that promote cellular life processes These become chromosomes during cell divisions Distinguish between diffusion and facilitated diffusion Diffusion is the process by which molecules or ions become scattered or are spread spontaneously from regions where they are in higher concentrations toward regions where they are in lower concentrations Diffusion is a passive process that occurs naturally Facilitated diffusion occurs when a substance that is not normally soluble in lipids combines with a receptor protein carrier molecule This union forms a compound that is soluble in lipids and diffuses to the other side of the membrane This receptor then releases the substance allowing for reuse of the carrier molecule Name three factors that increase the rate of diffusion These include a short distance over which the diffusion will occur a large concentration of the molecules and an increase in temperature of the diffusing substances Explain how diffusion aids in gas exchange within the body Diffusion allows the oxygen molecules that are in high concentrations on one side of the capillary wall to move to areas of lower concentration At the same time the carbon dioxide molecules that are in high concentrations are moving to areas of lower concentration Define osmosis Osmosis is a special type of diffusion involving water This is when water molecules diffuse from a region of higher water concentration to a region of lower water concentration Define osmotic pressure The ability of osmosis to generate enough pressure to lift a volume of water is called osmotic pressure Explain how the number of solute particles in a solution affects its osmotic pressure When the number of solute particles is great the water concentration will be lowered while the osmotic pressure will be greater Water will diffuse toward solutions with greater osmotic pressure Distinguish among solutions that are hypertonic hypotonic and isotonic Hypertonic refers to a solution that has a higher osmotic pressure than that of the cell This causes the cell to shrink as water moves out of the cell Hypotonic refers to a solution that has a lower osmotic pressure than that of the cell This causes the cell to swell and possibly burst as water moves into it Isotonic refers to a solution that has the same osmotic pressure as body fluids This allows the cell size to remain unchanged as water or solutes are not being pulled in any specific direction Define filtration Filtration is the process by which molecules are forced through a membrane by pressure Explain how filtration moves substances through capillary walls Blood pressure is the force that allows water and dissolved substances to move through the capillary walls forming tissue fluid Explain why active transport is called a physiological process whereas diffusion is called a physical process A physiologic process is defined as a living process It requires energy A physical process is defined as a passive process It requires no energy Explain the function of carrier molecules in active transport Carrier molecules are proteins that have binding sites that combine with the particles being transported This union triggers the release of cellular energy and this causes the shape of a carrier molecule to be altered This allows the passenger molecule to move through the membrane Distinguish between pinocytosis and phagocytosis Pinocytosis is the process by which cells take in tiny droplets of liquid from their surroundings The cell membrane becomes indented and breaks down integrating the water into the cytoplasm Phagocytosis is the process by which solid material is taken inside the cell The process is the same as pinocytosis except that solid material is taken inside the cell Describe receptor-mediated endocytosis How might it be used to deliver drugs across the blood-brain barrier Receptor-mediated endocytosis is where protein molecules extend through the cell membrane and are exposed on its outer surface The proteins become binding sites for specific substances found in the interstitial fluid These are then allowed to enter the cell It would be useful in the blood-brain barrier if there were a specific receptor that could be triggered to allow substances such as a drug to cross the membrane Explain how transcytosis includes endocytosis and exocytosis Transcytosis is the selective and rapid transport of a substance or particle from one end of a cell to the other It also enables substances to cross barriers formed by tightly connected cells List the phases in the cell life cycle Why is interphase not a time of cellular rest The phases in the life cycle of a cell include mitosis cytoplasmic division cytokinesis interphase and differentiation Interphase is the stage in the life cycle of a cell where young cells grow manufacture compounds new organelles are made and the chromosomes and centrioles replicated Name the two processes included in cell reproduction The first is the process by which the nuclear portions of the cell divide karyokinesis The second process is where the cytoplasm divides cytokinesis These two processes together are called mitosis Describe the major events of mitosis Prophase is the first stage of mitosis where the chromosomes appear scattered throughout the nucleus The nuclear envelope dissolves and the sister chromatids are attached by the centromere A spindle-shaped group of microtubules forms between the centrioles as they move apart Metaphase is the second stage of mitosis The chromosomes move along the spindle fibers and align midway between the centrioles Spindle fibers become attached to the centromere of the chromosomes Anaphase is where the centromere of the chromatids separate and the chromatids become individual chromosomes These are pulled apart toward the opposite sides of the cell Telophase is the final stage of mitosis where the chromosomes complete their migration toward the centrioles It is much like prophase but with everything reversed The nuclear envelope reforms and the chromosomes become invisible Explain how the cytoplasm is divided during cellular reproduction The cytoplasm is pinched off beginning in anaphase and completes itself at the end of telophase There may be more cytoplasm in one of the new daughter cells than in the other Explain what happens during interphase Interphase is the stage in the life cycle of a cell where young cells grow manufacture compounds new organelles are made and the chromosomes and the centrioles replicate Define differentiation Differentiation is the process by which cells develop different characteristics in structure and function Explain how differentiation may reflect repression of DNA information Special proteins activate some genes and repress others The way these are activated do not determine the type of cell that it will become How does loss of genetic control cause cancer In a healthy cell oncogenes are not expressed and the tumor suppressor genes are expressed As a result cell reproduction is under control Cancer begins in a single cell when an oncogene is turned on or a tumor suppressor gene is turned off If a mutation during chromosome division occurs cancer could result Distinguish between a stem cell and a progenitor cell Stem cells divide mitotically to yield two stem cell daughters or a stem cell and a progenitor cell which may show the beginnings of differentiation Progenitor cells give rise to progenitors or more differentiated cells of a restricted lineage Distinguish between totipotent cell and pluripotent cell Totipotent means the cells can give rise to every cell type Bluripotent means that their daughter cells can follow any of several pathways but not all of them Explain how differentiated cells can have the same genetic instructions but look and function very differently As cells specialize they use some genes and ignore others Chapter Cellular Metabolism Define anabolism and catabolism Anabolism uses energy to build large molecules from smaller ones Catabolism releases energy by breaking large molecules into smaller ones Distinguish between dehydration synthesis and hydrolysis Dehydration synthesis is a special form of anabolism where larger molecules are formed by removing an OH hydroxyl group from the end of one molecule and an H hydrogen atom from the end of another The OH and H combine to form H O water and the ends of the two molecules join by sharing the remaining oxygen atom Hydrolysis is the opposite of dehydration synthesis In hydrolysis a large molecule is split apart at a certain point and a hydrogen atom is attached to one of the new molecules while a hydroxyl group is attached to the other Both of these processes can occur over and over until the original molecule is altered to the cell s needs In short dehydration synthesis dehydrates a molecule and hydrolysis rehydrates it Define peptide bond A peptide bond is found in proteins It is formed during dehydration synthesis when the carbon atom of one amino acid joins with the nitrogen atom of the other amino acid Define enzyme An enzyme is usually a globular protein that catalyzes the reactions of substances by lowering the activation energy required to cause the desired effect How does an enzyme interact with its substrate The surface of an enzyme contains areas called active sites that will bind to a specific substrate only When the correct substrates are attached to the active sites called an enzyme-substrate complex the enzyme alters the shapes of the substrates in a way that promotes the reaction All enzymes demonstrate this specificity to its substrates To illustrate an enzyme-substrate complex is like a lock-and-key model with the enzyme as the lock and the substrate as the key Although many keys may fit the lock only one type of key will make it work List three factors that increase the rates of enzyme-controlled reactions The three factors are an increase in the enzyme concentration an increase in the substrate concentration and the general efficiency of the particular enzyme How are enzymes usually named Enzymes are generally named for the substrate it interacts with plus the suffix -ase For instance the enzyme that interacts with lipids is called lipase Define cofactor A cofactor is a separate non-protein molecule that binds to an enzyme to aid in the reaction Usually a cofactor is a non-organic molecule A coenzyme is a cofactor that is an organic molecule Explain why humans require vitamins in their diets Vitamins are organic substances that either cannot be synthesized by the human body or are synthesized in quantities that are inadequate For this reason vitamins must be consumed in the diet Explain how an enzyme may be denatured Since enzymes are proteins they can be denatured This is the process of breaking the hydrogen bonds within the protein thereby rendering it useless High heat excessive radiation or electricity and certain chemicals and fluids with extreme pH values cause denaturation A good example is the egg white during frying It starts a clear color and turns white upon application of the heat This is the protein being denatured This is a permanent process and cannot be reversed Define energy Energy by definition is the ability to do work Explain how the oxidation of molecules inside cells differs from the burning of substances outside cells The burning of a substance outside the cell usually requires large amounts of energy to start the reaction This burning indiscriminately breaks all chemical bonds in the substance and releases the energy as light and heat Oxidation inside the cell utilizes enzymes that require less activation energy controls the by-products released and uses certain energy capturing molecules to trap about one-half of the released energy for use elsewhere The rest is lost as heat Define cellular respiration The controlled sequential process of oxidation and energy recapture is referred to as cellular respiration Distinguish between anaerobic and aerobic respiration During cellular respiration the oxidative processes that occur in the absence of oxygen are called anaerobic respiration The oxidative processes that require the presence of oxygen for their reactions are called aerobic respiration Explain the importance of ATP to cellular processes ATP is the primary energy-carrying molecule in the cell It acts as a rechargeable battery for cellular processes by carrying energy in the terminal bond of the phosphate molecule and returning to recapture energy when it is used Without ATP the cell would die Describe the relationship between ATP and ADP molecules ATP releases its energy by breaking off the third or terminal phosphate molecule When this occurs it becomes ADP with only two phosphate molecules The ADP returns to recharge by picking up a third phosphate molecule with energy and the cycle repeats Define metabolic pathway A metabolic pathway is a sequence of enzyme-controlled reactions required to convert substances into useable forms These pathways are interconnected so that substances can be catabolized or anabolized per the needs of the cells at that particular time Describe the starting material and products of glycolysis Glucose is the starting material for glycolysis In order for glucose to be used for energy production it must be broken down by enzymes To begin ATP donates one phosphate molecule to the end of the glucose and the glucose is rearranged into fructose Then another ATP donates a phosphate molecule to the other end These first steps are called phosphorylation because phosphates are being used in the alteration of the molecule At this point the fructose is split into two three-carbon sugars A second phosphate is again added to each molecule and two hydrogen atoms are separated from each for use in the electron transport system The molecules each lose one phosphate molecule to an ADP molecule making two ATP At this point the molecules are rearranged twice to produce a pyruvic acid configuration with an attached phosphate In the final step the phosphate is lost to an ADP converting to ATP and the result is pyruvic acid In the presence of oxygen a pyruvic acid molecule is oxidized into an acetyl group that combines with a molecule of coenzyme A This step also releases two hydrogen atoms for each converted acetyl group In the absence of oxygen the pyruvic acid is converted into lactic acid When oxygen is again available the lactic acid is converted back into pyruvic acid for use in energy production State the products of the citric acid cycle The final products of the citric acid cycle Kreb s cycle are ATP molecules ATP molecules can be used The other two ATP molecules must be reused to start the process over again How are carbohydrates stored In the presence of excess glucose such as after a meal cells send the sugar into anabolic pathways for conversion into glycogen for storage The liver and the muscle cells do the majority of the storage because they need constant reserves for activity If the glycogen reserves have been filled the excess glucose is converted into fat and stored in fat tissues Because the body can perform this conversion without limits overeating can cause obesity Explain how one enzyme can regulate a metabolic pathway Typically the first enzyme in a pathway regulates the rate at which the pathway can work This enzyme is called a rate-limiting enzyme because it is present in a limited quantity and once saturated with substrates the rate of reaction will not increase Describe how a negative feedback mechanism can help control a metabolic pathway The final product of the pathway can inhibit the rate-limiting enzyme As the final product accumulates it inhibits the rate of the first enzyme regardless of the concentration of substrates This negative feedback mechanism helps prevent excess product from being produced Explain the chemical basis of genetic information Deoxyribonucleic acid DNA is a nucleic acid that contains the genetic information It is composed of the -carbon sugar deoxyribose a phosphate group and one of several organic nitrogenous bases The four bases associated with DNA are adenine thymine cytosine and guanine These bases pair systematically which bind the two long polynucleotide chains together The entire molecule is then twisted into a double helix Describe the chemical makeup of a gene A gene is a specific blueprint for a protein or enzyme Depending on how the base pairs are arranged they will code for different proteins Each gene is a variation of the possible proteins that code for a specific trait Describe the general structure and components of a DNA molecule A DNA molecule looks like a ladder in form It is composed of two polynucleotide chains with a backbone of sugars and phosphates and nitrogenous bases projecting outward on one side The sugar phosphate backbones make the uprights of the ladder while the nitrogenous bases linked together by hydrogen bonds make the rungs The bases are paired in only one pattern across the DNA molecule Adenine A binds only with thymine T and cytosine C binds only with guanine G These combinations are called complimentary base pairs Because the DNA molecule is so large it is twisted into a double-helix to conserve space Distinguish between the functions of messenger RNA and transfer RNA A messenger RNA mRNA molecule is a special type of RNA that is made of the complementary base sequences necessary for the production of a protein from the DNA molecule Transfer RNA tRNA is a group of RNA molecules that bind to activated amino acids in the cytoplasm and bring them to the mRNA molecule for assembly into a protein A tRNA molecule can bind with only one kind of amino acid Therefore since there are twenty different amino acids there must be at least twenty different kinds of tRNA molecules Distinguish between transcription and translation The process by which a mRNA molecule is formed from DNA is called transcription The synthesis of protein molecules from the mRNA is called translation Explain two functions of ribosomes in protein synthesis In protein synthesis a ribosome moves along with the mRNA and knits together a chain of amino acids by attaching itself to a portion of the mRNA and bonding with the complementary amino acid on a tRNA molecule As it moves along the mRNA it attaches each amino acid in sequence and releases the empty tRNA back into the cytoplasm Distinguish between a codon and an anticodon The sequences of nucleotides on a mRNA molecule are called codons These are complimentary sets of bases from the DNA molecule An anticodon is the compliment of the complimentary sequence on the mRNA molecule Each is a set of three nucleotides that describe an amino acid Explain how a DNA molecule is replicated During a phase before cell reproduction an enzyme called DNA polymerase breaks the hydrogen bonds between the complimentary base pairs of the DNA molecule As the DNA molecule splits and unwinds new nucleotides bond with the exposed nucleotides of the parental strand and a new sugar-phosphate backbone is built The result is two complete DNA molecules each containing one parental strand and one daughter strand These DNA molecules are then separated so that each new cell receives one complete DNA molecule Define mutation and explain how mutations may originate A mutation is defined as a mistake in or damage to the DNA strand that is not corrected and is passed on to the new cells Mutations can occur during replication when an incorrect nucleotide or extra nucleotides bind to the parental DNA strand Mutations can also occur if sections of the DNA strands are deleted misplaced or attached to the wrong chromosome Define repair enzyme If the mutation to a DNA molecule occurs only on one strand the cell uses special enzymes called repair enzymes to clip out the defective portion and rebuild it correctly Explain how a mutation may affect an organism s cells or not affect them Because of the importance of the DNA molecule there are many safeguards against mutation For instance there are sixty-one codons that specify the twenty amino acids If the mutation occurs in the third nucleotide of a codon it is likely that this mutation will still yield the correct amino acid If the mutation is in the second codon the new sequence will generally yield a structure similar enough to the original amino acid that the effect would not be significant There are two copies of each chromosome in an adult cell If one chromosome is mutated the genes of the second chromosome will usually provide enough normal blueprints to maintain the health of the cell If a mutation occurs in a cell of an adult it will probably go unnoticed because of the many normal cells around it If the mutation occurs in the cell of an embryo or child the results can be catastrophic because that cell may be the first or be the parent to many other cells as the infant grows Chapter Tissues Define tissue A tissue is a group of cells performing a specialized structural or functional role Name the four major types of tissue found in the human body The four major tissue types are epithelial connective muscle and nervous Describe the general characteristics of epithelial tissues Epithelial tissues cover the body surfaces cover and line internal organs and compose glands Because they cover the surfaces of all cavities and hollow organs they always have a free surface one exposed to the outside or having an open space Epithelial tissues always anchor to connective tissue by a noncellular layer called the basement membrane Generally epithelial tissues lack blood vessels Epithelium reproduces readily and heals quickly They are tightly packed with little intercellular material Because of this they serve as excellent barriers Other functions include secretion absorption excretion and sensory reception Distinguish between simple epithelium and stratified epithelium Simple epithelium occurs as a single cell or a single sheet of cells Stratified epithelium consists of layers of cells Explain how the structure of simple squamous epithelium provides its function Simple squamous epithelium consists of a single layer of think flattened cells These fit together like floor tiles and the nuclei are broad and thin Substances diffuse easily through this tissue Because of this simple squamous epithelium lines the alveoli of the lungs forms the walls of capillaries lines the insides of blood vessels and covers the membranes that line body cavities Because it is so thin simple squamous epithelium is damaged easily Name an organ that includes each of the following tissues and give the function of the tissue Simple squamous epithelium Found in the walls of capillaries it functions to allow the exchange of oxygen and waste products between the blood and the cells Simple cuboidal epithelium Found in kidney tubules it functions in secretion and absorption Simple columnar epithelium Found in the intestinal tract it functions in secretion of digestive fluids and absorption of nutrient molecules Psuedostratified columnar epithelium Found in the passages of the respiratory system the ciliated free surface moves the mucous produced by goblet cells up the respiratory tract and out of the airways Stratified squamous epithelium Forming the outer layer of the skin epidermis it becomes hardened with keratin and makes a tough dry protective covering Stratified cuboidal epithelium Found in the larger ducts of salivary glands it provides extra protection Stratified columnar epithelium Found in the male urethra the goblet cells provide mucous for lubrication Transitional epithelium Forming the inner lining of the urinary bladder because of its stretchable nature it forms a barrier that prevents the contents of the urinary tract from diffusing back into the body fluids Define gland A gland is composed of cells specialized to produce and secrete substances Most commonly these cells are columnar or cuboidal epithelium One or more of these cells constitutes a gland Distinguish between an exocrine gland and an endocrine gland Exocrine glands secrete their products into ducts that open onto an internal or external surface Endocrine glands secrete directly into tissue fluid or blood Explain how glands are classified according to the structure of their ducts and the organization of their cells A single cell can make up an exocrine gland This is called a unicellular gland If it is made up of two or more cells it is called a multicellular gland Multicellular glands can be further subdivided into two groups based upon their duct structure A simple gland has an unbranched duct A compound gland has a branched duct These can be further classified into tubular glands epithelial lined tubes or acinar glands saclike dilatations Explain how glands are classified according to the function and the nature of their secretions Merocrine glands are glands that release fluid products through cell membranes without the loss of cytoplasm Apocrine glands lose small portions of their glandular cell bodies during secretion Holocrine glands are glands that release entire cells filled with secretory products They are also classed as secreting serous fluid or mucus Distinguish between a serous cell and a mucous cell Serous cells produce a watery fluid that has a high enzyme concentration Mucous cells produce a thick mucus that is rich in the glycoprotein mucin Describe the general characteristics of connective tissue Connective tissue is found throughout the body and is the most abundant type by weight It binds structures provides support serves as frameworks fills spaces stores fat produces blood cells protects against infection and helps repair damage These cells are not adjacent to each other like epithelial cells and have abundant intercellular material called matrix This material consists of fibers and a ground substance whose consistency varies from fluid to solid Connective tissue has a good blood supply and is well nourished Bone and cartilage are quire rigid however loose connective tissue adipose and fibrous connective tissue are more flexible Define matrix and ground substance Matrix is intracellular material between the connective tissue cells This matrix consists of a ground substance whose consistency varies from fluid to semisolid to solid The ground substance binds supports and provides a medium through which substances may be transferred between the blood and cells within the tissue Describe the three major types of connective tissue cells Fibroblasta fixed cell in connective tissues It produces fibers by secreting protein into the matrix of connective tissues Mast cellsanother fixed cell releases histamine and heparin Macrophageswandering cells that can detach and move about These are specialized to carry on phagocytosis Distinguish between collagen and elastin Collagen fibers are thick threadlike and made of the protein collagen They are formed in long parallel bundles and are flexible but not elastic That is they can bend but they cannot stretch They have great tensile strength and are important to structures such as tendons Elastin is the protein that elastic fibers originate from These fibers are branched and form complex networks They have low tensile strength but are very elastic That is they can be easily stretched and resume their original length and shape They are the primary component of the vocal cords Explain the difference between loose connective tissue and dense connective tissue Dense connective tissue has abundant collagenous fibers that appear white This is sometimes known as white fibrous connective tissue Loose connective tissue or areolar tissue has sparse collagenous fibers Explain how the quantity of adipose tissue in the body reflects diet Individuals are born with a certain number of fat cells Excess food calories are likely to be converted into fat and stored This illustrates that the amount of adipose tissue in a human is reflective of the individual diet Distinguish between regular and irregular dense connective tissue Regular dense connective tissue has organized patterns of the fibers It is very strong enabling the tissue to withstand pulling forces It often binds body parts together Irregular dense connective tissue has thicker interwoven and more randomly organized patterns of fibers This allows for the tissue to sustain tensions exerted from many different directions It is found in the dermis of the skin Distinguish between elastic and reticular connective tissues Elastic connective tissue is made up of yellow elastic fibers in parallel strands or in branching networks In the fibers of this tissue are collagen fibers and fibroblasts This tissue is found in the walls of certain hollow internal organs Reticular connective tissue is composed of thin collagenous fibers arranged in a three-dimensional network It supports walls of certain internal organs such as the liver spleen and lymphatic organs Explain why injured loose connective tissue and cartilage are usually slow to heal Because fibrous connective tissue and cartilage are so dense and so closely packed they lack a direct blood supply For this reason nutrients diffusing from outside tissues take a long time to reach the cells This makes injury repair a very slow process Name the major types of cartilage and describe their differences and similarities Hyaline the most common type of cartilage It looks somewhat like white plastic It is found at the ends of bones in many joints in the soft part of the nose and in the supporting rings of the respiratory passage It is also important in the development of bones Elastic is very flexible and its matrix contains many elastic fibers It is found in the external ears and in parts of the larynx Fibrocartilage a very tough tissue it contains many collagenous fibers It is designed to function as a shock absorber It forms the intervertebral disks and the protective cushions between bones in the knee and the pelvic girdle Describe how bone cells are organized in bone tissue The matrix for bone is laid down in thin layers called lamellae The lamellae are arranged in concentric patterns around tubes called osteonic canals Between the layers of lamellae the osteocytes are placed in depressions called lacunae This pattern of concentric circles forms a cylinder-shaped unit called the osteon Explain how bone cells receive nutrients An osteon is a cylinder-shaped unit that the concentric circular pattern of bones cells form Each osteonic canal contains blood vessels so that every cell is close to a nutrient supply Bone cells also have cytoplasmic processes called canaliculi that extend outward and attach to the membranes of other cells As a result nutrients move rapidly between the bone cells Describe the composition of blood Red blood cells are the cells that carry oxygen to and carbon dioxide from cells White blood cells function in immunity and infection control Platelets are cellular fragments that function in blood clotting Describe the general characteristics of muscle tissues Muscle tissues are contractile Muscle fibers within the tissue change shape to become shorter and thicker This causes muscle fibers to pull at the attached ends and move body parts Distinguish among skeletal smooth and cardiac muscle tissues Skeletal muscle tissue is found in the muscles attached to bones and can be controlled by conscious effort Because of this it is also called voluntary muscle tissue The cells or muscle fibers are long and threadlike with alternating bands of dark and light cross-markings called striations Each fiber has many nuclei located near the cell membrane When the muscle is stimulated by nerve fibers it contracts and relaxes Smooth muscle tissue is named for its lack of striations It is found in the intestinal tract urinary bladder blood vessels and other hollow organs It is not consciously controlled and is therefore called involuntary muscle Smooth muscle cells are shorter than those of skeletal muscle and has a single centrally located nucleus Cardiac muscle is found only in the heart Its cells which are striated are joined end to end by a specialized connection called an intercalated disk The cardiac muscle fibers are branched and interconnected in a complex network Although it is striated it cannot be controlled voluntarily Describe the general characteristics of nervous tissue Nervous tissue is found in the brain spinal cord and peripheral nerves It is composed of neurons nerve cells and supporting neuroglial cells Distinguish between neurons and neuroglial cells Nervous tissue is composed of two types of cells Neurons or nerve cells are sensitive to changes in their surroundings and respond to stimulation of impulses along nerve fibers In addition to neurons neuroglial cells serve to support the neurons and bind the nervous tissue together Neuroglial cells carry on phagocytosis and bring nutrients to the neurons as well as remove waste from cells They also serve to bind nervous tissue together In many ways these cells act as connective tissue found only in nervous tissue Explain why a membrane is an organ Two or more kinds of tissues grouped together and performing specialized functions constitute an organ For example epithelial membranes are usually composed of epithelial and underlying connection tissues Identify locations in the body of the four types of membranes Epithelial membranes cover body surfaces and line body cavities and organs Synovial membranes line joints Serous membranes line body cavities Mucous membranes line the cavities and tubes that open to the outside of the body Chapter Skin and the Integumentary System Define integumentary system The integumentary organ system is defined by the inclusion of the cutaneous membrane and the accessory organs within it It is more commonly known as the skin List the six functions of skin A protective covering Aids in body temperature regulation Retards water loss Houses sensory receptors Synthesizes various chemicals Secretes small quantities of waste substances Distinguish between the epidermis and the dermis The epidermis is the outermost layer of the skin and is composed of keratinized stratified squamous epithelium The dermis is the inner thicker layer and includes various tissues such as connective tissue epithelial tissue smooth muscle tissue nervous tissue and blood The epidermis and dermis are separated by a basement membrane that is anchored to the dermis by short fibrils Describe the subcutaneous layer The subcutaneous layer hypodermis lies beneath the dermis and consists largely of connective and adipose tissues The collagenous and elastic fibers run mostly parallel to the surface of the skin but also travel in all directions As a result there is no clear boundary between the dermis and the subcutaneous layer Explain what happens to epidermal cells as they undergo keratinization As new cells in the epidermis are produced they are pushed upwards from the basement membrane towards the outside of the skin As they get further from their nutrient source they die As the process occurs the maturing cells undergo a hardening process keratinization during which the cytoplasm develops strands of tough fibrous waterproof proteins called keratin These dead cells form many tough waterproof layers These dead cells are rubbed away as newer cells replace them List the layers of the epidermis The layers in the epidermis are Stratum basale the deepest layer Stratum spinosum a relatively thick layer Stratum granulosum a granular layer Stratum corneum a fully keratinized layer Stratum lucidum this layer appears between the stratum granulosum and stratum corneum in the thickened skin of the palms and soles Describe the function of melanocytes An important function of the skin is to protect the deeper tissues from the harmful effects of sunlight One method of accomplishing this is the production of melanin the dark pigment produced by melanocytes in the deeper layers of the epidermis and in the upper layers of the dermis Melanin absorbs light energy and protects deeper tissues Although melanocytes are found deep in the epidermis the pigment can be found in any of the nearby cells due to the melanocytes long pigment-containing extensions that pass upward between neighboring epidermal cells These extensions can then transfer the granular melanin to these other cells by a process called cytocrine secretion As a result the neighboring cells often contain more melanin than the melanocytes themselves Describe the structure of the dermis The dermis is composed largely of irregular dense connective tissue that includes tough collagenous fibers and elastic fibers in a gel-like substance It has fingerlike projections called papillae that help form the fingerprints The dermis also includes muscle tissue It is usually smooth muscle but striated muscle is also present in certain portions such as the face to help with voluntary facial movements The dermis contains both sensory and motor nerves It also contains blood vessels hair follicles sebaceous glands and sweat glands Review the functions of the dermal nervous tissue The dermal nervous tissue has both sensory and motor fibers Sensory fibers include Pacinian corpuscles which are stimulated by heavy pressure and Meissner s corpuscles which are sensitive to light touch The motor fibers stimulate dermal muscles and glands Explain the functions of the subcutaneous layer The subcutaneous layer contains adipose tissue that acts as an insulator conserving internal body heat and preventing the entrance of heat from the outside This layer also contains the major blood vessels that supply nutrients and oxygen to the skin Distinguish between a hair and a hair follicle Hair is present on all skin surfaces except the palms soles lips nipples and various parts of the external reproductive organs A hair follicle is a group of epidermal cells at the base of a tubelike depression The root of the hair occupies this follicle As these cells divide and grow they are pushed toward the surface and undergo keratinization and subsequent cell death The cells remains form the structure of a developing hair whose shaft extends away from the skin surface This shaft is called the hair Review how hair color is determined Genes that direct the type and amount of pigment produced by epidermal melanocytes determine hair color Bright red hair contains an iron pigment trichosiderin that does not occur in hair of any other color Gray hair is the result of a mixture of pigmented and unpigmented hair Describe how nails are formed Stratified squamous epithelial cells in the region known as the nail root form nails The whitish half-moon-shaped area called the lunula marks the nail root As these cells are pushed outward they are keratinized into a hard tissue that slides forward over the nail bed to which it remains attached Explain the function of sebaceous glands Sebaceous glands contain groups of specialized epithelial cells and are usually associated with hair follicles They are holocrine glands that secrete an oily substance called sebum a mixture of fatty materials and cellular debris that serve to keep the hair and skin soft pliable and relatively waterproof Distinguish between eccrine and apocrine sweat glands Certain sweat glands known as apocrine glands respond to emotional stress and become active when a person is emotionally upset frightened or experiencing pain They are most numerous in the armpits and groin These are usually connected to hair follicles The development of these glands is stimulated by sex hormones so they become mature at puberty Eccrine glands are not associated with hair follicles and function throughout life in response to elevated body temperature associated with environmental heat and physical exercise These sweat glands are found primarily on the forehead neck and back where they produce profuse sweating Explain the importance of body temperature regulation Body temperature regulation is vitally important because even slight shifts in body temperature can disrupt the rates of metabolic reactions Describe the role of the skin in promoting the loss of excess body heat In intense heat the nerve impulses stimulate the skin and other organs to release heat The muscles when active release heat The peripheral blood vessels dilate vasodilation which allows more of the warmed blood to be close to the outside for dispersal by radiation The deeper blood vessels constrict vasoconstriction forcing more blood to the surface The heart rate increases to circulate the blood faster The sweat glands are also stimulated to add perspiration to the skin for evaporation Explain how body heat is lost by radiation Radiation is the primary means of body heat loss This is accomplished when infrared heat rays escape from warmer surfaces to cooler surroundings Distinguish between conduction and convection Conduction is the process by which heat moves directly into the molecules of cooler objects in contact with its surface Convection is the process by which heat is carried away from the body by air molecules that circulate over the body Describe the body s responses to decreasing body temperature As excessive body heat is lost the brain triggers responses in skin structure For example the muscles in the walls of the dermal blood vessels contract decreasing the blood flow The sweat gland become inactive and skeletal muscles throughout the body contract slightly shivering Review how air saturated with water vapor may interfere with body temperature regulation The air can only hold so much of the water molecules If it is already saturated the person who is sweating will not have evaporation occur and they will be wet and uncomfortable Explain how environmental factors affect skin color Factors such as sunlight ultraviolet light and X-rays stimulate increased melanin production Describe three physiological factors that affect skin color The dermal blood supply affects skin color For example when the blood is well oxygenated the hemoglobin makes the skin appear pinkish When the blood is not well oxygenated the hemoglobin is darker and the skin appears bluish cyanosis If the blood vessels are dilated or constricted the skin will carotene which is especially common in yellow vegetables may give the skin a yellowish cast Illnesses may affect skin color Distinguish between the healing of shallow and deeper breaks in the skin If the break in the skin is very shallow the epithelial cells along the margin are stimulated to reproduce more rapidly These newly produced cells simply fill in the gap A deeper break involves the blood vessels The clot will form and tissue areas will seep into the area and dry This will then form a scab for underlying protection Fibroblasts then produce fibers that bind the edges of the wound together Growth factors are released to stimulate damaged tissue replacement Healing continues beneath the scab which sloughs off when healing is complete Distinguish among first- second- and third-degree burns A first-degree burn is a superficial partial-thickness burn An example would be a sunburn A second-degree burn is a deep partial-thickness burn Any burn that blisters is a second-degree burn A third-degree burn is a full-thickness burn It can burn away all the skin and muscles leaving bone exposed Describe possible treatments for a third-degree burn Skin grafts are one possible treatment An autograft is a piece of skin from the victim A homograft is one from a cadaver Skin grafts leave scaring List three effects of aging on the skin Aging skin affects appearance as age spots or liver spots appear and grow along with wrinkling and sagging Due to changes in the number of sweat glands and shrinking capillary beds in the skin elderly people are less able to tolerate the cold and cannot regulate heat Older skin has a diminished ability to activate vitamin D necessary for skeletal health Chapter Skeletal System Part A List four groups of bones based upon their shapes and name an example from each group Long bones femur and humerus Short bones tarsals and carpals Flat bones ribs scapulae and bones of the skull Irregular bones vertebrae and many facial bones Sketch a typical long bone and label its epiphyses diaphysis medullary cavity periosteum and articular cartilages See figure page Distinguish between spongy and compact bone Compact bone is comprised of tightly packed tissue that is strong solid and resistant to bending Spongy bone consists of numerous branching bony plates Irregular interconnected spaces occur between these plates thus reducing the weight of the bone Explain how central canals and perforating canals are related Central canals Haversian canals contain one or two small blood vessels and a nerve surrounded by loose connective tissue These vessels provide nourishment for the bone cells associated with the osteonic canals The osteonic canals run longitudinally Perforating canals Volkmann s canals run transversely and contain larger blood vessels and nerves by which the vessels and nerves in osteonic canals communicate with the surface of the bone and the medullary cavity Explain how the development of intramembranous bone differs from that of endochondral bone Intramembranous bones develop from sheetlike masses of connective tissue Some of the primitive connective tissue cells enlarge and differentiate into osteoblasts Spongy bone tissue is produced in all directions by these osteoblasts in the membrane Eventually the periosteum is developed by outside cells of the membrane of the developing bone Endochondral bones develop of masses of hyaline cartilage with shapes similar to the future bone structures These models grow rapidly for a while and then begin to undergo extensive changes The center of the diaphysis in long bones breaks down and disappears At the same time a periosteum forms from connective tissues that encircle the developing diaphysis The primary ossification center is formed Later on the secondary ossification centers form and spongy bone forms from this Distinguish between osteoblasts and osteocytes Osteoblasts are bone-forming cells Osteocytes are mature bone cells surrounded by matrix Explain the function of an epiphyseal plate The epiphyseal plate is a band of cartilage that is left between the primary and secondary ossification centers This plate includes rows of young cells that are undergoing mitosis and producing new cells As the epiphyseal plate thickens due to the new cells bone length is increased Explain how a bone grown in thickness A developing bone grows in thickness as compact bone tissue is deposited on the outside just beneath the periosteum Bone tissue is being eroded away on the inside by osteoclasts Define osteoclast Osteoclasts are large multinucleated cells that break down the calcified matrix Explain how osteoclasts and osteoblasts regulate bone mass Osteoclasts secrete an acid that dissolves the inorganic component of the calcified matrix and their lysosomal enzymes digest the organic components After the osteoclasts remove the matrix bone building osteoblasts invade the regions and deposit bone tissue Describe the effects of vitamin deficiencies on bone development Vitamin D is necessary for proper absorption of calcium in the small intestine If this is lacking rickets can develop or osteomalacia in adults Vitamin A is necessary for bone resorption during normal development Vitamin C is needed for collagen synthesis Lacking either Vitamin A or C can hinder normal bone growth Explain the causes of pituitary dwarfism and gigantism Pituitary dwarfism results from the failure of the pituitary gland to secrete adequate amounts of growth hormone Pituitary giantism results from the pituitary gland secreting an excessive amount of growth hormone prior to epiphyseal disk ossification Describe the effects of thyroid and sex hormones on bone development Thyroid hormone stimulates the replacement of cartilage in the epiphyseal disks of long bones with bone tissue Thyroid hormone can halt bone growth by causing premature ossification of the epiphyseal disks A deficiency in thyroid hormone may stunt growth as the pituitary gland depends upon thyroid hormone to stimulate the secretion of growth hormone Sex hormones promote the formation of bone tissue Female sex hormones have a slightly stronger effect than male sex hormones allowing females to reach their maximum heights at an earlier age than males Explain the effects of exercise on bone structure Physical exercise causes the skeletal muscle to contract and the resulting stress stimulates the bone tissue to thicken and strengthen On the other hand lack of physical exercise causes bone to thin and weaken Provide several examples to illustrate how bones support and protect body parts Bones of the feet legs pelvis and backbone support the weight of the body The bones of the skull protect the brain The rib cage and shoulder girdle protect the heart and lungs Describe a lever and explain how its parts may be arranged to form first- second- and third-class levers A lever has four basic components a a rigid bar or rod b a pivot or fulcrum on which the bar turns c an object or resistance weight that is moved and a force that supplies the energy for the movement of that part A first-class lever has the sequence of resistance-pivot-force Example of first-class levers would include scissors seesaw or hemostats A second-class lever has the sequence of pivot-resistance-force An example of a second-class lever would be a wheelbarrow A third-class lever would have the sequence of resistance-force-pivot Examples of third-class levers would include eyebrow tweezers or forceps Explain how upper limb movements function as levers The upper limb is a first-class lever as the forearm bones serve as the rigid bar while the hand is the resistance and the elbow joint is the pivot The triceps brachii supply the force This movement is when the forearm is straightened Describe the functions of red and yellow bone marrow Red marrow functions in the formation of red blood cells white blood cells and blood platelets Its red color is derived from the oxygen-carrying pigment hemoglobin Yellow marrow functions in fat storage and is inactive in blood cell production Explain the mechanism that regulates the concentration of blood calcium ions When the blood is low in calcium parathyroid hormone stimulates the osteoclasts to break down bone tissue releasing calcium salts from the intercellular matrix into the blood Conversely very high blood calcium inhibits the osteoclast activity and calcitonin from the thyroid gland stimulates the osteoblasts to form bone tissue storing the excess calcium in the matrix List three substances that may be abnormally stored in bone Bone tissue may accumulate lead radium or strontium Distinguish between the axial and appendicular skeletons The axial skeleton consists of the bones that make up the skull the hyoid bone the vertebral column and the thoracic cage The appendicular skeleton consists of the pectoral girdle the bones that comprise the upper and lower limbs and the pelvic girdle Name the bones of the cranium and facial skeleton The bones of the cranium include one frontal bone two parietal bones one occipital bone two temporal bones one sphenoid bone and one ethmoid bone The bones of the facial skeleton include two maxilla bones two palatine bones two zygomatic bones two lacrimal bones two nasal bones one vomer bone two inferior nasal conchae bones and one mandible bone Explain the importance of fontanels Fontanels permit some movement between the bones so that the developing skull is partially compressible and can change shape slightly This allows the infant s skull to pass more easily through the birth canal Describe a typical vertebra A typical vertebra contains the following that are generic to all types Body The body is drum-shaped and forms the thick anterior portion of the bone Pedicles These consist of two short stalks and project posteriorly Laminae These are two plates that arise from the pedicles and fuse in the back Spinous process These results from the laminae fusing Vertebral arch A bony arch comprised of the pedicles laminae and spinous process Vertebral foramen The opening through which the spinal cord passes Transverse process Projections from each side between the pedicles and laminae Superior and inferior articulating processes Cartilage covered facets that project either upward or downward where the vertebrae are joined to the one above and below it Intervertebral foramina Notches on the lower surfaces of the vertebral pedicles that form openings which provide passageways for the spinal nerves that communicate with the spinal cord Explain the differences among cervical thoracic and lumbar vertebrae The cervical vertebrae are distinctive due to the bifid spinous processes and transverse foramina in the transverse process The thoracic vertebrae are larger than the cervical vertebrae and have long pointed spinous processes that slope downward and facets on the side of their bodies that articulate with a rib Starting with the third thoracic vertebrae the bodies of these vertebrae increase in size The lumbar vertebrae have the largest bodies and short stubby spinous processes Describe the locations of the sacroiliac joint the sacral promontory and the sacral hiatus The sacroiliac joint occurs where the sacrum is wedged between the coxal bones of the pelvis and is united to them at its auricular surfaces by fibrocartilage The sacral promontory is the upper anterior margin of the sacrum Physicians use this to determine pelvis size for childbirth The sacral hiatus is the opening at the tip of the sacrum dorsally Names the bones that comprise the thoracic cage The thoracic cage includes the ribs thoracic vertebrae sternum and costal cartilages that attach the ribs to the sternum List the bones that form the pectoral and pelvic girdles The pectoral girdle consists of two clavicles and two scapulae The pelvic girdle consists of two coxal bones that articulate with each other anteriorly and with the sacrum posteriorly Name the bones of the upper limb The bones of the upper limb include a humerus a radius an ulna and several carpals metacarpals and phalanges Name the bones that comprise a coxa A coxal bone develops from three parts an ilium an ischium and a pubis that fuse together List the major differences that may occur between the male and female pelves The female iliac bones are more flared than the males The angle of the female pubic arch may be greater There may be more distance between the ischial spines and the ischial tuberosities The sacral curvature may be shorter and flatter The bones of the female pelvis are usually lighter more delicate and show less evidence of muscle attachments List the bones of the lower limb The bones of the lower limb include a femur a tibia a fibula and several tarsals metatarsals and phalanges Describe changes in trabecular bone and compact bone with aging Trabecular bone due to its spongy less compact nature shows the changes of aging first as they thin increasing in porosity and weakening the overall structure The vertebrae consist mostly of trabecular bone It is also found in the upper part of the femur whereas the shaft is more compact bone The fact that trabecular bone weakens sooner than compact bone destabilizes the femur which is why it is a commonly broken bone among the elderly Compact bone loss begins at around age forty and continues at about half the rate of loss of trabecular bone As remodeling continues throughout life older osteons disappear as new ones are built next to them With age the osteons may coalesce further weakening the overall structures as gaps form List factors that may preserve skeletal health Preserving skeletal health may involve avoiding falls taking calcium supplements getting enough vitamin D avoiding carbonated beverages phosphates deplete bone and getting regular exercise Part B Match the parts listed in column I with the bones listed in column II I II Coronoid process C Mandible Cribriform plate A Ethmoid bone Foramen magnum E Occipital bone Mastoid process F Temporal bone Palatine process D Maxillary bone Sella turcica G Sphenoid bone Supraorbital notch B Frontal bone Temporal process H Zygomatic bone Acromion process M Scapula Deltoid tuberosity K Humerus Greater trochanter I Femur Lateral malleolus J Fibula Medial malleolus O Tibia Olecranon process P Ulna Radial tuberosity L Radius Xiphoid process N Sternum Chapter Joints of the Skeletal System Part A Define joint A joint is a functional junction between bones Explain how joints are classified The type of tissue that binds the bones together at each junction can classify joints They can also be classified according to the degree of movement possible at the bony junctions Compare the structure of a fibrous joint with that of a cartilaginous joint A fibrous joint uses fibrous connective tissue to hold bones together that were in close contact with one another A cartilaginous joint uses hyaline or fibrocartilage to hold the articulation together Neither type allows much movement Distinguish between a syndesmosis and a suture A syndesmosis is characterized by bone being bound together by long fibers of connective tissue that form an interosseous ligament This type of joint has slight movement A suture has a thin layer of fibrous connective tissue that forms the sutural ligament This type of joint has no movement Describe a gomphosis and name an example A gomphosis is a joint formed by the union of a cone-shaped bony process in a bony socket The peglike root of a tooth fastened to a jawbone by a periodontal ligament is such a joint Compare the structures of a synchondrosis and a symphysis A synchondrosis uses bands of hyaline cartilage to unite to bones Many of these joints are temporary structures that disappear during growth This particular type of joint allows no movement A symphysis has the articular surfaces of bones covered with hyaline cartilage that is attached to a pad of fibrocartilage This particular type of joint allows a limited type of movement Explain how the joints between adjacent vertebrae permit movement Each of these are symphysis joints Between each vertebra there is an intervertebral disk that is composed of a band of fibrocartilage that surrounds a gelatinous core The disk absorbs shocks and helps equalize pressure between the vertebrae during body movement As each disk is slightly flexible the combined movements of many of the joints in the vertebral column allow the back to bend forward to the side or to twist Describe the general structure of a synovial joint A synovial joint will include the following components Articular cartilage Thin layer of hyaline cartilage on the ends of the articulating bones Joint capsule Tubular structure that has two distinct layers The outer layer is made up of dense fibrous connective tissue The inner layer is a shiny vascular membrane called the synovial membrane Synovial fluid A clear viscous fluid secreted by the synovial membrane for lubrication of the joint Ligaments Bundles of tough collagenous fibers that serve to reinforce the joint capsule Menisci Disks of fibrocartilage found in some synovial joints that serve as shock absorbers Bursae Fluid-filled sacs that cushion and aid the movement of tendons within a synovial joint Describe how a joint capsule may be reinforced Ligaments are used to bind the articular ends of bones together reinforcing the joint capsule These can be thickenings in the fibrous layer of the joint capsule or accessory structures that are located outside of the joint capsule Explain the function of the synovial membrane The synovial membrane covers all surfaces within the joint capsule except the areas the articular cartilage covers It fills spaces and irregularities within the cavity It secretes synovial fluid It may store adipose tissue It also reabsorbs the synovial fluid Explain the function of synovial fluid Synovial fluid helps to cushion moisten and lubricate the smooth cartilaginous surfaces within the joint It also supplies the articular cartilage with nutrients Define meniscus A meniscus is a disk of fibrocartilage that occurs in some synovial joints dividing them into two compartments It serves as a shock absorber and allows bony prominences to fit together easier Define bursa A bursa is a fluid-filled sac associated with freely moveable joints List six types of synovial joints and name an example of each type Type Example Ball-and-Socket Hip joint shoulder joint Condyloid Joints between the metacarpals and phalanges Gliding Joints between the various bones of the wrist and ankle Hinge Elbow joint knee joint Pivot Joint between the proximal end of the radius and ulna Saddle Joint between the carpal and metacarpal of the thumb Describe the movements permitted by each type of synovial joint Type Type of Movement Ball-and-Socket Movement in all planes as well as rotational movement around a central axis Condyloid Variety of movement in different planes but rotational movement is possible Gliding Sliding back and forth motion only Hinge Flexion and extension in one plane only Pivot Rotation around a central axis only Saddle Variety of movements Name the parts that comprise the shoulder joint The shoulder joint consists of the head of the humerus and the glenoid cavity of the scapula Name the major ligaments associated with the shoulder joint Coracohumeral ligament Connects the coracoid process of the scapula to the greater tubercle of the humerus Glenohumeral ligament Three binds of fibers that appear as thickenings in the ventral wall of the joint capsule and extend from the edge of the glenoid fossa to the lesser tubercle and the anatomical neck of the humerus Transverse humeral ligament Runs between the greater and lesser tubercles of the humerus Glenoidal labrum Attached along the margin of the glenoid fossa and forms a rim with a thick free edge that deepens the fossa Explain why the shoulder joint permits a wide range of movements The shoulder joint permits a wide range of movements due to the looseness of it attachments and the relatively large articular surface of the humerus compared to the shallow depth of the glenoid fossa The movements include flexion extension abduction adduction rotation and circumduction Name the parts that comprise the elbow joint The elbow joint includes the trochlea of the humerus the trochlear notch of the ulna the capitulum of the humerus and a fovea on the head of the radius Describe the major ligaments associated with the elbow joint Radial collateral ligament Connects the lateral epicondyle of the humerus to the annular ligament of the radius Annular ligament Connects the margin of the trochlear notch of the ulna and encircles the head of the radius Ulnar collateral ligament Connects the medial epicondyle of the humerus to the medial margin of the coronoid process It also connects posteriorly to the medial epicondyle of the humerus and to the olecranon process of the ulna Name the movements permitted by the elbow joint The only movement permitted between the humerus and ulna are flexion and extension The head of the radius however is free to rotate in the annular ligament which allows pronation and supination of the hand Name the parts that comprise the hip joint The hip joint consists of the head of the femur and the cup-shaped acetabulum of the coxal bone Describe how the articular surfaces of the hip joint are held together Acetabular labrum Horseshoe-shaped ring of fibrocartilage at the rim of the acetabulum and deepens the acetabular cavity encloses the head of the femur Iliofemoral ligament Connects the anterior inferior iliac spine of the coxal bone to the intertrochanteric line between the greater and lesser trochanters of the femur Pubofemoral ligament Extends between the superior portion of the pubis and the iliofemoral ligament Ischiofemoral ligament Originates on the ischium just posterior to the acetabulum and blends with the fibers of the joint capsule Explain why there is less freedom of movement in the hip joint than in the shoulder joint Muscles surround the joint capsule of the hip The articulating parts of the hip are held more closely together than those of the shoulder allowing considerably less freedom of movement Name the parts that comprise the knee joint The knee joint consists of the medial and lateral condyles at the distal end of the femur and the medial and lateral condyles at the proximal end of the tibia The femur also articulates anteriorly with the patella Describe the major ligaments associated with the knee joint Patellar ligament Continuation of a tendon from the quadriceps muscle group that extends from the margin of the patella to the tibial tuberosity Oblique popliteal ligament Connects the lateral condyle of the femur to the margin of the head of the tibia Arcuate popliteal ligament Extends from the lateral condyle of the femur to the head of the fibula Tibial collateral ligament medial collateral ligament Connects the medial condyle of the femur to the medial condyle of the tibia Fibular collateral ligament lateral collateral ligament Connects the lateral condyle of the femur and the head of the fibula Anterior cruciate ligament ACL Originates from the anterior intercondylar area of the tibia and extends to the lateral condyle of the femur Posterior cruciate ligament PCL Connects the posterior intercondylar area of the tibia to the medial condyle of the femur Explain the function of the menisci of the knee The menisci serve as shock absorbers They also function to compensate for the differences in shapes between the surfaces of the femur and tibia Describe the locations of the bursae associated with the knee Suprapatellar bursa Located between the anterior surface of the distal end of the femur and the quadriceps muscle group above it Prepatellar bursa Located between the patella and the skin Infrapatellar bursa Located between the proximal end of the tibia and the patellar ligament Describe the process of aging as it contributes to the stiffening of fibrous cartilaginous and synovial joints Joint stiffness is often the earliest sign of aging a Collagen changes cause the feeling of stiffness b Regular exercise can lessen the effects Fibrous joints are the first to begin to change and strengthen over a lifetime Synchondroses of the long bones disappear with growth and development Changes in symphysis joints of the vetebral column diminish flexiblility and decrease height Over time synovial joints lose elasticity Part B Match the movements in column I with the descriptions in column II I II Rotation D Moving part around an axis Supination A Turning palm upward Extension F Increasing angle between parts Eversion E Turning sole of foot outward Protraction C Moving part forward Flexion B Decreasing angle between parts Pronation H Turning palm downward Abduction I Moving part away from midline Depression G Lowering a part Chapter Muscular System Part A List the three types of muscle tissue The three types of muscle tissue are skeletal smooth and cardiac Distinguish between a tendon and an aponeurosis A tendon is a projection of connective tissue beyond the ends of the muscle that attaches to bone An aponeurosis is a broad fibrous sheet of connective tissue that connects muscles to adjacent muscles Describe the connective tissue coverings of a skeletal muscle Muscle fibers are grouped together in fascicles that are surrounded by a layer of connective tissue called the endomysium The fascicles are bundled together and surrounded by another layer of connective tissue called the perimysium which also fills the spaces between the fascicles Several layers of fibrous connective tissue called the epimysium which surrounds the entire muscle then cover the perimysium Distinguish between deep fascia subcutaneous fascia and subserous fascia Deep fascia is the portion of the network of the fasciae that surrounds and penetrates the muscles Subcutaneous fascia is the portion that lies just beneath the skin forming the subcutaneous layer Subserous fascia is the portion that forms the connective tissue layer of the serous membranes covering organs in various body cavities and lining those cavities List the major parts of a skeletal muscle fiber and describe the function of each part A muscle fiber is a single multinucleated cell which contracts when stimulated It is a thick elongated cylinder with rounded ends that may extend the entire length of the muscle Its component parts are Sarcolemma The specific name for a muscle fiber s cell membrane Sarcoplasm The specific name for a muscle fiber s cytoplasm It contains the many small oval nuclei and mitochondria Myofibrils The numerous threadlike proteins that lie parallel to one another and are contained in the sarcoplasm The arrangement of the two proteins below produces the striations seen in the skeletal muscle Myosin The primary protein of the myofibril It is a thick protein filament running longitudinally within the muscle fiber Actin The thin protein filaments arranged intertwined within the myosin filaments The alternating light and dark striations are named for their positions within the fiber A bands The primary location of the myosin filaments that produces the dark striations I bands The primary location of the actin filaments that produces the light striations Z lines The attachment point of the actin filaments at the ends of I bands They are arranged so that those of adjacent myofibrils side by side Sarcomere The segment of the myofibril between two successive Z lines This regular arrangement causes the muscle fiber to appear striated Sarcoplasmic reticulum S R The specific name for the endoplasmic reticulum The network of membranous channels that surround each myofibril running parallel to them Transverse tubules T-tubules The invaginations of the fiber s sarcoplasm that extend inward and pass completely through the fiber It is open to the outside of the sarcoplasm at both ends and contains extracellular fluid Each T-tubule likes between two enlarged portions of the S R called cisternae near the regions where the actin and myosin filaments overlap With the S R the T-tubules activate the muscle contraction mechanism Describe a neuromuscular junction Each skeletal muscle fiber is connected to a fiber from a nerve cell called a motor neuron The muscle fiber contracts only when stimulated by this specific fiber At the connection point between the never fiber and the muscle fiber the muscle fiber s sarcolemma is tightly coiled and heavily concentrated with mitochondria This region is known as the motor end plate The branches of the motor nerve fiber project into recesses synaptic clefts of the motor end plates and the distal ends are filled with mitochondria and synaptic vesicles that store chemicals called neurotransmitters This entire region is known as a neuromuscular junction Define motor unit and explain how the numbers of fibers within a unit affects muscular contractions The nerve fibers of a motor neuron are highly branched Each of these branches is connected to the motor end plate of a single muscle fiber When the motor neuron is stimulated the impulse is carried to all of the muscle fibers attached to its branches In this way a single motor neuron controls the contractions of many muscle fibers All the muscle fibers attached to this motor neuron and the motor neuron itself constitute a motor unit The fewer muscle fibers in the motor unit the finer the movements that can be produced Explain the function of a neurotransmitter substance A neurotransmitter is a chemical stored in the synaptic vesicles which when stimulated by a nerve impulse is released into the gap at the motor end plate and stimulates the fiber to contract Describe the major events that occur when a muscle fiber contracts Muscle fiber contraction is a complex process involving a number of cell parts and chemical substances that result in the sliding movement of the actin and myosin filaments and causes a contraction A myosin filament is composed of protein strands with globular ends called cross-bridges that extend outward along the length of the filament The actin filaments have ADP molecules attached to its surface that serve as active sites for linking the cross-bridges of the myosin filaments Although the process is not completely understood the sliding filament theory suggests that the myosin cross-bridge attaches to an actin active site and bends slightly pulling the actin with it It releases its attachment straightens and combines with another active site further down the actin filament causing the sarcomere to shorten When the nerve impulse reaches the distal end of its branch acetylcholine is released into the gap The acetylcholine diffuses rapidly across the motor end plate and combines with protein receptors in the sarcolemma This causes a muscle impulse to be generated and pass in all directions over the entire sarcolemma and through the T-tubules deep into the fiber The S R which contains a high concentration of calcium ions becomes more permeable and allows the ions to diffuse into the sarcoplasm When a high enough concentration is present in the sarcoplasm the linkages between the actin and myosin filaments occur and contraction takes place The calcium ions are moved quickly back into the S R by an active transport system calcium pump When enough calcium ions have been removed from the sarcoplasm the muscle relaxes At the same time the acetylcholine is rapidly decomposed by the enzyme cholinesterase This prevents a single nerve impulse from causing a sustained contraction Explain how ATP and creatine phosphate function in muscle contraction The basic energy source for muscle contraction comes from ATP molecules supplied by the mitochondria The cross-bridges of myosin contain the enzyme ATPase that causes ATP to decompose into ADP and phosphate thereby releasing energy The primary source of regeneration of ATP from ADP is creatine phosphate Creatine phosphate contains high-energy phosphate bonds and is four to six times more abundant in the muscle fibers than ATP Creatine phosphate cannot directly supply energy to the muscle fiber Instead it acts as a storehouse of energy for the ADP In the mitochondria the enzyme creatine phosphokinase creates creatine phosphate to be used for ATP synthesis The creatine phosphate in turn converts ADP into ATP by resupplying the phosphate molecule Describe how oxygen is supplied to skeletal muscles Oxygen is carried from the lungs by hemoglobin in the blood When the hemoglobin reaches the muscle the oxygen is transferred to the myoglobin in the muscle fiber Myoglobin is similar to hemoglobin in its oxygen capacity and reduces the muscle s need for continuous blood supply during contraction Describe how an oxygen debt may develop When skeletal muscles have been used where they have exceeded their oxygen reserves anaerobic respiration must take over Anaerobic respiration changes glucose into pyruvic acid and due to the lack of oxygen the pyruvic acid is converted into lactic acid The lactic acid diffuses out of the muscles and is taken to the liver by the blood The liver can change lactic acid back into glucose however this conversion also requires the use of ATP During strenuous exercise primarily the muscles and not the liver use the oxygen so the lactic acid accumulates Oxygen debt then is defined as the amount of oxygen needed by the liver to convert the lactic acid back into glucose plus the amount needed by the muscles to resynthesize ATP and creatine phosphate and return them to their original concentrations Because the conversion of lactic acid into glucose is a slow process it may take several hours to repay the oxygen debt Explain how muscles may become fatigued and how a person s physical condition may affect tolerance to fatigue If a muscle is exercised strenuously for a long period it may lose its ability to contract This is called muscle fatigue This condition may result from an interruption in a muscle s blood supply or from the depletion of acetylcholine in the motor nerve fibers The most common cause of muscle fatigue is due to the accumulation of lactic acid from anaerobic respiration The lactic acid causes factors such as pH to change so that the muscle fibers no longer respond Occasionally a muscle becomes fatigued and develops a cramp simultaneously A cramp is a painful condition in which the muscle contracts spasmodically but does not completely relax This may be caused by a lack of ATP A person who exercises can stimulate new capillaries to grow within the muscles supplying more oxygen and nutrients to the muscle fibers This will allow more aerobic respiration to take place thereby decreasing dependence on anaerobic respiration which results in less lactic acid buildup Explain how actions of skeletal muscles affect maintenance of body temperature Two-thirds of the energy released in cellular respiration is lost as heat Muscle accounts for most of the total body mass so when muscles are active large amounts of heat are produced This is circulated throughout the body by the blood thereby supporting the maintenance of body temperature Define threshold stimulus A muscle fiber remains unresponsive until a certain amount of stimulus is applied This minimal strength required is called the threshold stimulus Explain all-or-none response When a muscle fiber contracts it always contracts to the fullest extent possible Because a muscle fiber cannot contract partially this phenomenon is called the all-or-none response Describe the staircase effect A muscle fiber that has been inactive can be subjected to a series of stimuli such that it undergoes a series of twitches with complete relaxation in between However the strength of each successive contraction increases reaching a maximum This phenomenon is called the staircase effect Explain recruitment Because all of the muscle fibers in a motor unit are controlled by a single motor neuron all of the fibers will contract in response to the motor neuron stimulus When the nerve impulse is so great that one motor neuron cannot handle it the excess impulse is shunted to other motor neurons This ability to cause more than one motor unit to respond to a stimulus is called motor unit recruitment Explain how a skeletal muscle can be stimulated to produce a sustained contraction If a muscle is exposed to a series of stimuli increasing in frequency a point is reached where the muscle is unable to complete its relaxation period before the next stimulus arrives This stacking of twitches causes a sustained contraction Distinguish between a tetanic contraction and muscle tone A tetanic contraction tetany results when a sustained forceful contraction lacks even partial relaxation Muscle tone tonus is a response to nerve impulses originating repeatedly from the spinal cord and traveling to small numbers of muscle fibers within a muscle Muscle tone is responsible for maintaining posture Muscle tone appears to be a conscious phenomenon because when the person is rendered unconscious the body will collapse Distinguish between concentric and eccentric contractions and explain how each is used in body movements Concentric Shortening occurs If a person lifts an object the muscles remain taut their attached ends pull closer together and the object is moved The muscle contracts with force greater than resistance and shortens Eccentric lengthening occurs The muscle contracts with less force than resistance and lengthens Laying a book down on a table is an example Distinguish between fast-contracting and slow-contracting muscles Fast-contracting muscles white muscles contain less myoglobin and have a poorer blood supply in relation to slow-contracting muscles red muscles They have fewer mitochondria and a reduced respiratory capacity They do have a better-developed sarcoplasmic reticulum and a higher ATPase activity This allows them to contract rapidly A slow-contracting muscle has a lot of myoglobin and a well-developed blood supply They have many mitochondria to carry on aerobic respiration As a result they can generate the necessary ATP needed for contraction They contract for long periods of time prior to muscle fatigue becoming a factor Compare the structures of smooth and skeletal muscle fibers Smooth muscle fibers are shorter than skeletal muscle fibers Smooth muscle fibers have once centrally nucleus They are elongated with tapering ends The actin and myosin filaments are present throughout the length of smooth muscle fibers but are thinner and more random The smooth muscle fibers also lack transverse tubules and their sarcoplasmic reticulum is not well developed Distinguish between multiunit and visceral smooth muscles Multiunit smooth muscle features fibers that are somewhat disorganized and occur as separate fibers rather than in sheets It can be found in the iris of the eyes and in the walls of blood vessels Multiunit smooth muscle tissue contracts only after stimulation by motor nerve impulses Visceral smooth muscle is composed of sheets of spindle-shaped cells in close contact with one another This type which is more common is found in the walls of hollow visceral organs such as the stomach intestines urinary bladder and uterus The fibers of visceral smooth muscle are capable of stimulating each other So when one fiber is stimulated the impulse may excite adjacent fibers that in turn may excite others Visceral smooth muscle fibers also display rhythmicity a pattern of repeated contractions These two features of visceral smooth muscle are largely responsible for peristalsis Define peristalsis and explain its function Peristalsis consists of alternating contractions and relaxations of the longitudinal and circular muscle fibers It functions to force the contents of a tube along its length Compare the characteristics of smooth and skeletal muscle contractions Both smooth and skeletal muscle contractions involve the reactions of actin and myosin are triggered by membrane impulses and the release of calcium ions and use energy from ATP molecules The differences between their contractions are Skeletal muscles use acetylcholine as the neurotransmitter Smooth muscle uses acetylcholine and norepinephrine as its neurotransmitters Several hormones that cause either contractions or alter the amount of response to the neurotransmitters affect smooth muscles Smooth muscle is slower to contract and relax than skeletal muscle However smooth muscle can maintain a forceful contraction for a longer period of time with a given amount of ATP Unlike skeletal muscle smooth muscle fibers can change length without changes in tautness As a result as the hollow organs become filled the muscles can stretch without internal pressure changing Compare the structures of cardiac and skeletal muscle fibers Cardiac muscle occurs only in the heart It is made of striated muscle fibers joined end-to-end forming three-dimensional networks The internal components are the same except that the cisternae of the cardiac fibers are not as well developed and contain fewer calcium ions than skeletal muscle fibers The T-tubules of the cardiac muscle fibers are more developed and release more calcium ions which comes from the extracellular fluid in response to stimuli This enables the cardiac muscle fibers to maintain contractions for a longer period of time The cardiac muscle cells are joined to each other at the ends by means of intercalated disks These disks help hold adjacent cells together and transmit the force of the contraction from cell to cell The disks are also low in electrical resistance so the muscle impulse travels from cell to cell rapidly Cardiac muscle is self-exciting rhythmic and the entire network responds in an all-or-none manner Compare the characteristics of cardiac and skeletal muscle contractions Skeletal muscle can contract individually Cardiac muscle works in a network When one portion of the cardiac muscle network is stimulated the impulse travels to the other fibers in the network It then contracts as a unit It is self-exciting and rhythmic and the entire network responds in an all-or-none manner Distinguish between a muscle s origin and its insertion The origin of a muscle is the end of the muscle attached to an immovable part The insertion is the end of a muscle attached to a moveable part When a muscle contracts the insertion is pulled toward the origin Define prime mover synergist and antagonist The prime mover is the muscle that is primarily responsible for a certain movement A synergist is a muscle that aids the prime mover in its action to move a part An antagonist is a muscle that acts against the prime mover For instance if the prime mover raises the arm the antagonist lowers it The combination of both the prime mover and antagonist working at the same time will cause the part to remain rigid This aids in maintaining posture balance and locomotion Part B Match the muscles in column I with the descriptions and functions in column II I II Buccinator F Compresses the cheeks Epicranius E Consists of two parts the frontalis and the occiptialis Lateral pterygoid H Pulls the jaw from side to side Platysma G Extends over the neck from the chest to the face Rhomboideus major C Can raise and adduct the scapula Splenius capitis D Can pull the head into an upright position Temporalis A Inserted on the coronoid process of the mandible Zygomaticus B Draws the corner of the mouth upward Biceps brachii P Strongest supinator of the forearm Brachialis O Strongest flexor of the elbow Deltoid K Abducts the arm Latissimus dorsi J Pulls the shoulder back and downward Pectoralis major M Pulls the arm forward and across the chest Pronator teres N Rotates the arm medially Teres minor L Rotates the arm laterally Triceps brachii I Primary extensor of the elbow Biceps femoris V A hamstring muscle External oblique T Compresses the contents of the abdominal cavity Gastrocnemius S A plantar flexor of the foot Gluteus maximus U Largest muscle in the body Gluteus medius X Abducts the thigh Gracilis W Adducts the thigh Rectus femoris R A member of the quadriceps group Tibialis anterior Q Inverts the foot Part C Which muscles can you identify in the bodies of these models whose muscles are enlarged by exercise See page Chapter Nervous System I Basic Structure and Function Distinguish between neurons and neuroglial cells Neurons are the structural and functional cells reacting to the physical and chemical changes in their environment Neuroglia are the supporting cells necessary for nourishing and maintaining the neurons among other functions Explain the relationship between the central nervous system and the peripheral nervous system The central nervous system CNS is composed of the brain and the spinal cord The peripheral nervous system PNS is composed of all of the peripheral nerves that connect all of the parts of the body with the CNS List three general functions of the nervous system The nervous system functions in three ways Sensory The sensory function is accomplished by means of sensory receptors that note changes in their environment Integrative The CNS can take the impulses from all of the sensory receptors and combine them to make perceptions and sensations about the environment Motor The CNS can send impulses along some peripheral nerves to effectors in the muscles and glands in response to changes in the internal and external environment Describe the generalized structure of a neuron All neurons have a cell body and nerve fibers that are responsible for nerve impulse conduction to and from the cell body The cell body soma or perikaryon contains granular cytoplasm mitochondria lysosomes a Golgi apparatus and many microtubules Neurofibrils extend in a network throughout the microtubules and support them Also found in the cytoplasm are Nissl bodies which are membranous sacks of rough endoplasmic reticulum Cytoplasmic inclusions contain glycogen lipids or pigments The nucleus is large and spherical with a conspicuous nucleolus The two kinds of nerve fibers extending from the cell body are called dendrites and axons The many dendrites are typically highly branched to provide receptive surfaces dendritic spines for other neurons to communicate A neuron usually has only one axon arising from the axon hillock It is a nearly smooth cylindrical process with uniform diameter It is filled with cytoplasm containing many mitochondria microtubules and neurofibrils It is specialized to conduct nerve impulses away from the cell body The axon starts as a single fiber but may branch off into collaterals which may end in presynaptic terminals Define myelin Surrounding larger axons and dendrites of peripheral nerves are sheaths of neuroglial cells called Schwann cells These cells are wound tightly around the fibers and as a result the cell membranes are layered closely together with little or no cytoplasm between them The layers are composed of a lipoprotein called myelin which forms a myelin sheath on the outside of the fibers The outermost Schwann cells contain most of the cytoplasm and their nuclei remain outside the myelin sheath This layer is known as neurolemma or neurolemmal sheath Distinguish between myelinated and unmyelinated nerve fibers A myelinated nerve fiber is one which is bound by Schwann cells longitudinally along its length The Schwann cells wrap tightly around the nerve fiber and form a myelin sheath Unmyelinated nerve fibers lack these sheaths In this case these Schwann cells are not wound around the axons but simply for a grove or valley in which the axon sits Myelinated medullated nerve fibers appear white Unmyelinated nerve fibers appear gray Explain how neurons are classified on the basis of their structure Nerve fibers can be classified into three main groups Bipolar Bipolar neurons have only two nerve fibers one is the axon and one is the dendrite They are from opposite sides of the cell body Unipolar Unipolar neurons have a single nerve fiber extending from the cell body From there it branches in two directions one branch extends into a peripheral body part and serves as a dendrite The other extends into the CNS and acts like an axon Multipolar Multipolar neurons have one axon and many other extensions from the cell body that serve as dendrites Explain how neurons are classified on the basis of their function Nerve fibers can be classified into three groups Sensory Sensory afferent neurons sense changes inside or outside the body by means of receptors ends or nearby receptor cells They send impulses to the CNS in response to these changes Most of these neurons are unipolar with some bipolar Interneurons Interneurons association or internuncial neurons are multipolar neurons found in the CNS They link with other neurons and send impulses from one part of the CNS to another Motor Motor efferent neurons are multipolar and send impulses from the CNS to muscles or glands There are two types of motor neurons that control smooth or cardiac muscle Accelerator neurons increase muscle activity while inhibitory neurons decrease muscle activity Discuss the functions of each type of neuroglial cell The PNS has only one type of neuroglial cell the Schwann cell The CNS has four different types of neuroglial cells They are Astrocyte Astrocytes are star-shaped cells located between neurons and blood vessels They provide structural support and transport substances between the neurons and blood vessels Astrocytes are joined together by gap junctions providing a channel for circulating calcium ions Other duties include metabolism of substances such as glucose keeping the synaptic clefts free of excess ions and neurotransmitters and scar tissue formation after injury Oligodendrocytes Oligodendrocytes function in myelin production By extending numerous cellular processes an oligodendroctye can provide myelin sheaths to several different axons Because of this arrangement no neurilemmal sheaths are formed Microglia Microglia are small cells found throughout the CNS They provide support and phagocytize bacteria and debris Ependyma Ependyma are ciliated cuboidal or columnar cells found as the inner lining of the central canal and as a single-layered membrane covering the ventricles of the brain They are joined together by gap and tight junctions and provide a porous layer for substances to diffuse between the interstitial fluids of the brain and cerebrospinal fluid in the ventricles Describe how an injured nerve fiber may regenerate If the axon of a peripheral nerve is separated from the cell body the distal portion deteriorates and the fragments are removed by macrophages The proximal end then develops new sprouts and nerve growth factors from surrounding neuroglia cause the sprouts to grow At the same time remaining Schwann cells proliferate and surround the new axon If a sprout grows into the remaining basement membranes of the original tract the new fiber may rejoin with its original connection If the injured axon is from a neuron in the CNS the lack of a myelin sheath prevents the new fiber from being guided to its original connection Therefore regeneration in the CNS is very unlikely An injury to the cell body of a neuron usually causes death to the entire fiber and no regeneration will occur Explain how a membrane may become polarized A cell in its normal state has a negatively charged interior with respect to the exterior This is accomplished by transport mechanism channels that let potassium ions move easily in and out and keep sodium and calcium ions under tight control Define resting potential Because the movement of sodium ions into the cell is slower than the movement of potassium out of the cell there are more positive ions cations outside and more negative ions anaions inside The difference in the charges between the two sides of the cell s membrane is about millivolts in relation to the interior charge This difference in charge is defined as the resting potential because it shows a potential to do the work send a message Distinguish between depolarizing and hyperpolarizing If in response to a stimulus the resting potential becomes more negative the cell is said to be hyperpolarizing If the stimulus causes the resting potential to become less negative the cell is said to be depolarizing List the changes that occur during an action potential When enough stimuli have accumulated to cause the threshold potential to be released the area stimulated opens its sodium channels As the sodium ions rush in the inside of the cell becomes momentarily positive At the same time potassium channels open to allow the potassium ions out This causes the inside of the cell to return to a negative charge repolarization The entire sequence takes less than th of a second Distinguish between action potentials and nerve impulses An action potential occurs at a specific site When an action potential occurs at the trigger zone of a nerve cell it sends an electrical impulse to the adjacent membrane This causes an action potential at the next site This occurs in a wavelike sequence without losing amplitude from the beginning of the fiber to the end and is known as a nerve impulse Define refractory period After an action potential passes the fiber needs time to return to its resting potential This time is called the refractory period The refractory period has two parts The first is the absolute refractory period This lasts about th of a second and is the period when no