Introductory Biology II Midterm Study Guide (BIOL 104)

Exam 2 Study Guide Chapter 24: Be able to define and distinguish between innate and acquired immunity Innate immunity is present before any exposure to pathogens and is effective from the time of birth (involves nonspecific responses to pathogens) Acquired immunity, or adaptive immunity, develops after exposure to agents such as microbes, toxins, or other foreign substances (It involves a very specific response to pathogens) Understand the role of skin and mucous membrane in innate immunity Innate defenses include barrier defenses, phagocytosis, antimicrobial peptides Mucus traps and allows for the removal of microbes Many body fluids including saliva, mucus, and tears are hostile to microbes The low pH of skin and the digestive system prevents growth of microbes Know what a hemocyte is and the two mechanisms it uses to defend the host Hemocytes circulate within hemolymph and carry out phagocytosis Hemocytes also secrete antimicrobial peptides that disrupt the plasma membranes of bacteria Understand the role of the TLR and its general method of action Groups of pathogens are recognized by TLR, Toll-like receptors Activate immune cell responses, innate immunity Know the roles of the tonsils and spleen Tonsils serve to trap antigens for removal by the immune system Spleen is similar to the lymph nodes this organ filters blood and removes old blood cells Know the role of the mast cell in inflammation Following an injury, mast cells release histamine, which promotes changes in blood vessels; this is part of the inflammatory response These changes increase local blood supply and allow more phagocytes and antimicrobial proteins to enter tissues Pus, a fluid-rich in white blood cells, dead microbes, and cell debris, accumulates at the site of inflammation Understand how an initial injury causes a primary response that is followed by recruitment of other cells Inflammatory response Understand the role of a fever and what may happen when it lasts for an extended period of time Fever is a systemic inflammatory response triggered by pyrogens released by macrophages, and toxins from pathogens Coma or brain damage can occur if a fever lasts too long Define the MHC and the role that it plays in NK cell protection All cells in the body (except red blood cells) have a class 1 MHC (major histocompatibility complex) protein on their surface Cancerous or infected cells no longer express this protein; natural killer (NK) cells attack these damaged cells T cells bind to antigen fragments presented on a host cell NK cell detects normal MCH expression and spares the healthy epithelial cell NK cell detects loss of MHC and kills the virus infected epithelial cell Differentiate between B-cells, T-cells, and cytokines White blood cells are called lymphocytes, contribute to immunological memory B cells- attack invaders outside the cell, mature in the bone marrow T cells- attack invaders insider the cell, mature in the thymus Cytokines are secreted by macrophages and dendritic cells to recruit and activate lymphocytes B cells and T cells have receptor proteins that can bind to foreign molecules Each individual lymphocyte is specialized to recognize a specific type of molecule, each cell has over 100,000 identical antigen receptors Know the role of the variable region in the TCR and BCR Variable region, composed of 110-130 amino acids, give the antibody its specificity for binding antigen. Each T cell receptor consists of two different polypeptide chains; can bind to an antigen that is free or on the surface of a pathogen The tips of the chain form a variable (V) region; the rest is a constant (C) region B cell receptors bind to specific, intact antigens The B cell receptor consists of two identical heavy chains and two identical light chains Amino acid sequence varies extensively from one B cell to another Define a plasma cell and the role that it has in long term immunity The first exposure to a specific antigen represents the primary immune response During this time, effector B cells called plasma cells are generated, and T cells are activated to their effector forms Plasma cells help maintain humoral immunity, antibody production Distinguish between antibodies and BCRs B cell receptors bind to specific, intact antigens, contain transmembrane region, light chains, and heavy chains Antibodies/immunoglobulins are structurally similar to B cell receptors but lack transmembrane regions that anchor receptors in the plasma membrane Distinguish between class I and class II MHC molecules Class I MHC molecules are found on almost all nucleated cells of the body; they display peptide antigens to cytotoxic T cells Class II MHC molecules are located mainly on dendritic cells, macrophages, and B cells Dendritic cells, macrophages, and B cells are antigen-presenting cells that display antigens to cytotoxic T cells and helper T cells Understand how clonal collection results in long term immunity and understand how the body protects against self-reactivity In the body there are few lymphocytes with antigen receptors for any particular epitope The binding of a mature lymphocyte to an antigen induces the lymphocyte to divide rapidly= clonal selection An hypothesis which states that an individual lymphocyte (specifically, a B cell) expresses receptors specific to the distinct antigen, determined before the antibody ever encounters the antigen. Binding of Ag to a cell activates the cell, causing a proliferation of clone daughter cells. Clonal selection of B cells generates antibody-secreting plasma cells, the effector cells of humoral immunity Cytotoxic T cells make CD8, a surface protein that greatly enhances interaction between a target cell and a cytotoxic T cell The activated cytotoxic T cell secretes proteins that destroy the infected target cell Distinguish between humoral and cell-mediated immune responses Humoral immune response involves activation and clonal selection of B cells, resulting in production of secreted antibodies Cell-mediated immune response involves activation and clonal selection of cytotoxic T cells Helper T cells aid both responses Define neutralization and opsonization in immunity Neutralization occurs when a pathogen can no longer infect a host because it is bound to an antibody Opsonization occurs when antibodies bound to antigens increase phagocytosis Know the difference between active and passive immunity, understand the role this plays in immunization Active immunity develops naturally in response to an infection, can develop following immunization Passive immunity provides immediate, short-term protection, it is conferred naturally when IgG crosses the placenta from mother to fetus or when IgA passes from mother to infant in breast milk It can be conferred artificially by injecting antibodies into a non-immune person Understand how allergies occur and why acute responses can be life threatening Allergies are exaggerated (hypersensitive) responses to antigens called allergens In localized allergies such as hay fever, IgE antibodies produced after first exposure to an allergen attach to receptors on mast cells Mast cells release histamine and other mediators that cause vascular changes leading to typical allergy symptoms Define antigenic variation and distinguish it from the approach used by Tuberculosis Through Antigenic variation, some pathogens are able to change epitope expression and prevent recognition Tuberculosis avoids destruction by modifying their surface to prevent recognition or by resisting breakdown following phagocytosis Chapter 26 Define a hormone and distinguish between endocrine and paracrine signaling hormones are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body Hormones reach all parts of the body, but only target cells are equipped to respond endocrine system secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior nervous system conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells; chemical signals bind to receptor proteins on target cells, only target cells respond to the signal Understand the difference between processes that are regulated by the nervous system and the endocrine system Endocrine glands are ductless and secrete hormones directly into surrounding fluid Paracrine signals act on cells near the secreting cell Autocrine signals act on the secreting cell itself Define a synapse and know the reason a target cell would decrease the number of receptors on its surface At synapses, neurons often secrete chemical signals called neurotransmitters that diffuse a short distance to bind to receptors on the target cell Receptors will down-regulate and decrease sensitivity when there is prolonged exposure to high levels of a hormone. Distinguish between pheromones and all other hormones Neurohormones are a class of hormones that originate from neurons in the brain and diffuse through the bloodstream Pheromones are chemical signals that are released from the body and used to communicate with other individuals in the species Pheromones mark trails to food sources, warn of predators, and attract potential mates Know where the receptors for lipid soluble molecules are and why it is different for the water soluble receptors Lipid-soluble hormones (steroid hormones, cortisol) pass easily through cell membranes, while water-soluble hormones (polypeptides and amines, insulin, epinephrine, thyroxine) do not Water-soluble hormones are secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors Lipid-soluble hormones diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells The solubility of a hormone correlates with the location of receptors inside or on the surface of target cells Understand the concept of the signal transduction pathway and what role the second messenger plays Signal transduction pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression This triggers the release of messenger molecules that activate enzymes and result in the release of glucose into the bloodstream Understand the basic effect that ligand binding has on the estradiol receptor Know how one hormone can have a different effect on different cell types and on the same cell type Understand why the blocking of COX2 activity results in the alleviation of pain Selective COX-2 inhibitors are a type of non-steroidal anti-inflammatory drug (NSAID) that directly targets cyclooxygenase-2, COX-2, an enzyme responsible for inflammation and pain Be able to identify and distinguish between positive and negative feedback A negative feedback loop inhibits a response by reducing the initial stimulus Negative feedback regulates many hormonal pathways involved in homeostasis In a positive feedback system, the output enhances the original stimulus. A good example of a positive feedback system is child birth. During labor, a hormone called oxytocin is released that intensifies and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born. The birth ends the release of oxytocin and ends the positive feedback mechanism. Know the role of insulin and glucagon in glucose homeostasis Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis Insulin reduces blood glucose levels by promoting the cellular uptake of glucose, slowing glycogen breakdown in the liver, promoting fat storage Glucagon increases blood glucose levels by stimulating conversion of glycogen to glucose in the liver, stimulating breakdown of fat and protein into glucose Understand why Type I diabetes is most often seen in children Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells Know how a hormone such as ecdynsone can induce both the development of the juvenile body and the adult body In insects, molting and development are controlled by a combination of hormones: A brain hormone stimulates release of ecdysone from the prothoracic glands Juvenile hormone promotes retention of larval characteristics Ecdysone promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics Understand the primary differences between the anterior and posterior pituitary The posterior pituitary stores and secretes hormones that are made in the hypothalamus The anterior pituitary makes and releases hormones under regulation of the hypothalamus Why is oxytocin called the love drug? The release of oxytocin by the pituitary gland acts to regulate two female reproductive functions: childbirth, breast-feeding, sex Understand the concept of a hormone cascade pathway and why the anterior pituitary is a good example of this concept A hormone can stimulate the release of a series of other hormones, the last of which activates a non-endocrine target cell; this is called a hormone cascade pathway The release of thyroid hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland; pathway usually regulated by negative feedback Distinguish between tropic and non-tropic hormones, be able to classify a hormone into these categories Nontropic hormones target nonendocrine tissues Nontropic hormones produced by the anterior pituitary are Prolactin (PRL)- stimulates lactation in mammals Melanocyte-stimulating hormone (MSH)- skin pigmentation, fat metabolism A tropic hormone regulates the function of endocrine cells or glands The four strictly tropic hormones are Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adrenocorticotropic hormone (ACTH) Understand the general effect and benefit that HGH has for athletes, understand this same concept in a non-athlete Growth hormone (GH) is secreted by the anterior pituitary gland and has tropic and nontropic actions It promotes growth directly and has diverse metabolic effects It stimulates production of growth factors An excess of GH can cause gigantism, while a lack of GH can cause dwarfism Understand the relationship between PTH and Vitamin D Two antagonistic hormones regulate the homeostasis of calcium (Ca2+) in the blood of mammals Parathyroid hormone (PTH) is released by the parathyroid glands PTH increases the level of blood Ca2+ It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food Distinguish between the roles of the two lobes in the adrenal gland, pay special attention to their respective responses to stress The adrenal glands are adjacent to the kidneys Each adrenal gland actually consists of two glands: the adrenal medulla (inner portion) and adrenal cortex (outer portion) The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), they are secreted in response to stress-activated impulses from the nervous system, they mediate various fight-or-flight responses The adrenal cortex releases a family of steroids called corticosteroids in response to stress; These hormones are triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary Chapter 28: Differentiate between nerve nets, ganglia, and brains The transmission of information depends on the path of neurons along which a signal travels A nerve net is a series of interconnected nerve cells Ganglia= clusters of neurons, processing of information Brain= more complex organization of neurons Know why the squid was a good model organism for the study of the nervous system The squid possesses extremely large nerve cells and is a good model for studying neuron function Distinguish between the roles of sensory, motor, and interneurons. Know where they are most likely to be found. Sensory neurons= Sensors detect external stimuli and internal conditions and transmit information along Sensory information is sent to the brain or ganglia, where interneurons integrate the information Motor output leaves the brain or ganglia via motor neurons, which trigger muscle or gland activity Understand the roles of the CNS and PNS, in broad terms know what the Parasympathetic and Sympathetic divisions of the PNS do the fight or flight/rest and digest responses A central nervous system (CNS) where integration takes place; this includes the brain and a nerve cord A peripheral nervous system (PNS), which brings information into and out of the CNS Autonomic nervous: involuntary, breathing/digestion (sympathetic = fight or flight, parasympathetic= rest& digest) Somatic: voluntary physical action Differentiate between nerve bodies, dendrites, and axons Most of a neuron’s organelles are in the cell body Most neurons have dendrites, highly branched extensions that receive signals from other neurons The axon is typically a much longer extension that transmits signals to other cells at synapses An axon joins the cell body at the axon hillock Distinguish the roles of the neuron and glia cells Most neurons are nourished or insulated by cells called glia Information is transmitted from a presynaptic cell (a neuron) to a postsynaptic cell (a neuron, muscle, or gland cell) Understand the way a cell establishes a resting membrane potential Every cell has a voltage (difference in electrical charge) across its plasma membrane called a membrane potential The resting potential is the membrane potential of a neuron not sending signals In a mammalian neuron at resting potential, the concentration of K+ is greater inside the cell, while the concentration of Na+ is greater outside the cell Sodium-potassium pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane These concentration gradients represent chemical potential energy The opening of ion channels in the plasma membrane converts chemical potential to electrical potential A neuron at resting potential contains many open K+ channels and fewer open Na+ channels; K+ diffuses out of the cell Resting potential can be modeled by an artificial membrane that separates two chambers The concentration of KCl is higher in the inner chamber and lower in the outer chamber K+ diffuses down its gradient to the outer chamber Negative charge builds up in the inner chamber At equilibrium, both the electrical and chemical gradients are balanced In a resting neuron, the currents of K+ and Na+ are equal and opposite, and the resting potential across the membrane remains steady Know in what location, inside or outside, concentration of Na and K are greater the concentration of K+ is greater inside the cell, while the concentration of Na+ is greater outside the cell Differentiate between a voltage gated ion pump and an ATP driven pump, know how these play roles in establishing membrane potentials of neurons Neurons contain gated ion channels that open or close in response to stimuli Ions, (Na+, K+, Cl-) Understand the stages of the action potential At resting potential: Most voltage-gated Na+ and K+ channels are closed, but some K+ channels (not voltage-gated) are open When an action potential is generated: Voltage-gated Na+ channels open first and Na+ flows into the cell During the rising phase, the threshold is crossed, and the membrane potential increases During the falling phase, voltage-gated Na+ channels become inactivated; voltage-gated K+ channels open, and K+ flows out of the cell Know what role the voltage gated pumps play in the term all or none depolarization depolarization, a reduction in the magnitude of the membrane potential depolarization occurs if gated Na+ channels open and Na+ diffuses into the cell Graded potentials are changes in polarization where the magnitude of the change varies with the strength of the stimulus Understand how the voltage gated pumps allow for single directional flow of an action potential Action potentials travel in only one direction: toward the synaptic terminals The speed of an action potential increases with the axon’s diameter In vertebrates, axons are insulated by a myelin sheath, which causes an action potential’s speed to increase Myelin sheaths are made by glia— oligodendrocytes in the CNS and Schwann cells in the PNS Understand why the myelin sheath is important and how a squid is able to have axons with no myelin While the squid axon is very large in diameter it is unmyelinated which decreases the conduction velocity substantially. Squids have nerve nets Define the Nodes of Ranvier and their role in the propagation of the action potential Action potentials are formed only at nodes of Ranvier, gaps in the myelin sheath where voltage-gated Na+ channels are found Action potentials in myelinated axons jump between the nodes of Ranvier in a process called saltatory conduction Distinguish between the reflex and the conscious responses of the nervous system, where is this information processed? A reflex is the body’s automatic response to a stimulus The spinal cord also produces reflexes independently of the brain The spinal cord conveys information from the brain to the PNS Know the role of cerebrospinal fluid and how it is different from plasma The central canal of the spinal cord and the ventricles of the brain are hollow and filled with cerebrospinal fluid The cerebrospinal fluid is filtered from blood and functions to cushion the brain and spinal cord CSF is nearly protein-free compared with plasma and has some modified electrolyte levels The major differences from plasma are: The pCO2 is higher (50 mmHg) resulting in a lower CSF pH (7.33) The protein content is normally very low (0.2g/l) resulting in a low buffering capacity The glucose concentration is lower The chloride concentration is higher The cholesterol content is very low Distinguish between grey and white matter Gray matter, which consists of neuron cell bodies, dendrites, and unmyelinated axons White matter, which consists of bundles of myelinated axons Know the three embryonic regions of the brain and what parts of the brain develop from each region Forebrain: telencephalon, diencephalon Midbrain: mesencephalon Hindbrain: metencephalon, myelencephalon Know the major roles of each region of the brain stem The brainstem coordinates and conducts information between brain centers The brainstem has three parts: the midbrain, the pons, and the medulla oblongata The midbrain contains centers for receipt and integration of sensory information The pons regulates breathing centers in the medulla The medulla oblongata contains centers that control several functions including breathing, cardiovascular activity, swallowing, vomiting, and digestion Understand how the biological clock responds to external cues such as sunlight Circadian Rhythms What role does the corpus callosum play and how is it related to its structure? A thick band of axons called the corpus callosum provides communication between the right and left cerebral cortices The right half of the cerebral cortex controls the left side of the body, and vice versa Understand why numbers and math are more difficult to handle during sleep. The core of the brainstem has a diffuse network of neurons called the reticular formation This regulates the amount and type of information that reaches the cerebral cortex and affects alertness The hormone melatonin is released by the pineal gland and plays a role in bird and mammal sleep cycles Sleep is essential and may play a role in the consolidation of learning and memory Dolphins sleep with one brain hemisphere at a time and are therefore able to swim while “asleep” The cerebellum is important for coordination and error checking during motor, perceptual, and cognitive functions It is also involved in learning and remembering motor skills Define neural plasticity and understand its role in learning Neural plasticity describes the ability of the nervous system to be modified after birth Changes can strengthen or weaken signaling at a synapse Understand why Alzheimer’s must be caught early if a cure is ever discovered. Alzheimer’s disease is a mental deterioration characterized by confusion, memory loss, and other symptoms Alzheimer’s disease is caused by the formation of neurofibrillary tangles and amyloid plaques in the brain A successful treatment in humans may hinge on early detection of amyloid plaques There is no cure for this disease though some drugs are effective at relieving symptoms How Memories Are Formed: Short term mem- long-term in hippocampus- neurons communicate at synapses; if two neurons communicate repeatedly, efficiency of communication increases (long-term potentiation, how memories are stored) Synapses deterioriate. Hippocampus loses 5% of neurons every decade. Drop in production of neurotransmitters like acetyl, vital for memory. Memories encoded most strongly when paying attention Chronic stress- body becomes flooded with chemicals, resulting in a loss of brain cells and an inability to form new ones Depression - memory problems, serotonin decrease makes you inattentive Isolation slower rate of memory decline, social interaction helps use brain Eat well, increased blood flow, give brain a workout