Muscles Notes Modified for online

Biology 20 Muscular System Notes Chapter 10 Name:____________________ Muscles and More Goals for this Chapter: Observe and compare the three types of muscle tissue Describe the action of actin and myosin in muscle contraction and heat production Identify the sources of energy for muscle contraction Explain how skeletal muscles support other body systems Identify conditions that impair the healthy functioning of muscle systems Describe the benefits of exercise for maintaining healthy muscles Text book Pg 330-359 Magnificent Muscle Facts The human body has more than 650 muscles Waste energy keeps you warm! No two muscles in the body have exactly the same function. When one muscle is paralyzed, either stability of the body part is impaired or some specific movement is lost. A muscle is pretty efficient, using about 35-50% of its potential energy Muscle fibers are thinner than a human hair and can support up to 1,000 times its own weight. The strongest muscle in the human body is masseter? Muscle is Latin for “little mouse” MY Oh MY Muscles Types of Muscles 286385-381000 43688003365500 Types of muscle Skeletal muscle Striated & tubular Many nuclei Voluntary Attached to bones Functions in circulatory system to help move blood back to the heart (contract against veins) Release heat Move bones Allow us to stand upright 350964517716500Cardiac muscle Striated (little lines in muscle), tubular and branched. One nucleus Involuntary control Found only in walls of heart ______________________ Smooth muscle 45161201968500Non-striated One nucleus Involuntary control Found in walls of internal organs Ex: sphincter muscles of esophagus, intestines, and urethra Does not fatigue easily Muscular System Supports the Skeletal System 1631953429000 Action of Muscles During contraction a muscle shortens when stimulated by an excitatory nerve During relaxation a muscle lengthens when stimulated by an inhibitory nerve Muscles Cooperate Muscles can only pull therefore they must work in pairs pulling against each other (antagonistic) Eg. Biceps-triceps Bicep pulls to bend a joint (___________) Tricep pulls to straighten a joint (___________) 308610011430000-11430011430000 Muscle Type Location in Body Structure Function Cardiac Muscle Smooth Muscle Skeletal Muscle Muscle Organization Muscle An organ surrounded by connective tissue and composed of several tissues eg. bundles of muscle cells and nervous tissue. Muscle fibres muscle cells in the bundles unlike “typical”cells. Up to 20 cm in length contain many nuclei Organelles within the cells (fibres) 3171520118515the cell membrane is called the sarcolemma 333028055580the endoplasmic reticulum is the sarcoplasmic reticulum 5987850-293155886330149655832330-12795557210905312556163304052554798906572552066501103654755930786854937010-87547717705636545939301625654225650234205413673018020539560101611253784290199285385737014204534955702244852968530310165278128065725the cytoplasm is known as sarcoplasm. 2508150-1206902295390-479701752510-922501390350-47970790230-85770631470-76410498270-54090367590-25650266430-38250110910-44730283464012382500012382500 Skeletal Muscle Structure Muscle fibres (a specialized cell) are organized into larger bundles up to 20 cm in length Connective tissue wraps fibref Another layer of connective tissue bundles fibres Muscle Structure Myofibrils are composed of small subunits called sarcomeres Sarcomeres are the functional unit of a muscle between z disc (zigzaggy) Composed of actin and myosin (protein chains) Actin is the thin filament Myosin is the thick filament 3263906413500 40322521018500 F Skeletal Muscle Structure Blood vessels and nerves run between bundles or fibres Cell membranes of muscle cells are called sarcolemma Fibres are composed of myofilaments Myofilaments can be thin (actin filament) or thick (myosin filament) and overlap to give alternating light and dark bands. Muscle Contraction One sarcomere is composed of both actin (thin) and myosin (thick) filaments _____________ divide sarcomeres _____________ is the area where myosin can be seen Dark areas are A-bands (myosin & actin) Lighter areas are I-bands (actin) Muscle contraction can be explained by the Sliding Filament Theory The lengths of thick filaments (myosin) and thin filaments (actin) do not change during contraction. The current hypothesis is that the thin and thick filaments slide past each other during contraction Sliding Filament Theory Sliding Filament Theory Signal to muscle from a nerve Sarcoplasmic reticulum releases stored Ca2+ Ca2+ binds to troponin which in turn moves tropomyosin (protein that covers the binding sites for myosin heads) allowing the myosin to bind calcium is returned to the sarcoplasmic reticulum through active transport when the contraction stops Links: http://www.youtube.com/watch?v=gJ309LfHQ3M http://www.youtube.com/watch?v=0kFmbrRJq4w Energy for Muscles There are three main sources for muscles: Stored creatine phosphate Anaerobic respiration Aerobic respiration of glucose and fatty acids Muscle fibre contraction is paid for using ATP After a few muscle twitches ATP is spent in the muscles. The ATP that is used afterwards comes from the 3 sources listed above. 6686559271000 High energy molecule found in amongst the sliding filament adds Pi to ADP to replenish the ATP being consumed in the muscles consumed in 8 secs replenished during rest Slow Twitch Muscles – Type I Takes longer to contract (100 ms for tetanus) Contains myoglobin (stores oxygen in muscle) gives red colour to muscle, more blood, more mitochondria ATP produced aerobically (sports like long distance running, swimming, biking) in size with training Fast Twitch Muscles – Type II Fast contractions (7 ms for tetanus) Anaerobic ATP generation Glycogen rich, light colour Fatigue quickly (vulnerable to lactate) Sports like sprinting, weight lifting Eye movements use fast twitch contractions Increase in thickness with training Intermediate – Type IIa Fast twitch Increased aerobic capacity Formed from endurance training 10.2 – Muscles, Health, and Homeostasis Even at rest, muscles are still contracting at some level We rely on proper muscle tone to maintain our posture, and to keep us upright Complications of the Muscular System Muscles are generally vulnerable to injuries that result from sudden stress However, muscles are one of the few organ groups whose activity can be impaired through lack of use Muscular atrophy results from a lack of movement of the muscle Common Muscular Disorders Muscular Dystrophy- Botulism- Fibromyalgia- Cramps Contracture Crush syndrome Delayed onset muscle soreness Myositis Common Injuries to Muscular System Torn muscles Stretched tendons Torn ligaments Joint sprains Joint dislocation Exercise & Muscle Contraction Regular exercise allows muscles to develop and use energy more efficiently Regularly used muscles grow due to the increase in the size of the individual muscle fibre, not because of the increase in the number of fibres The increase in the size of muscles is known as hypertrophy Homeostasis Our muscular system allows us to maintain homeostasis Our muscles generate heat through the use of ATP during contraction, and muscles allow blood vessels to contract and dilate to move warm blood throughout the body As well, many of our processes in our other body systems rely on the movement of muscles to regulate actions Relationship to Other Systems Relationship Circulatory System Respiratory System Digestive System Excretory System 1. Three types of muscle tissue are located in various organs in the body. Complete the table below to summarize the characteristics of each type of muscle tissue. Characteristics of Muscle Tissues Type Structure Voluntary/ Involuntary? Location in the Body Smooth Cardiac Skeletal Use the following information to answer the next question. Although they differ in various characteristics, all muscles types have one function. They create movement within the body. Review the figure opposite. It explains that sensors in the body continuously detect stimuli. Information is sent to control centres, which in turn direct responses to the stimuli. Responses are carried out by effectors—all of which are types of muscle tissue. Suppose you are asleep and the doorbell rings. You stumble to your feet and move toward the door, open it and speak with your visitor. Think of the many changes occurring in your body as you awaken and respond to the sound of the doorbell. 2. Complete the table below to show how the three types of muscle tissue help you respond to the doorbell. Smooth Muscle Cardiac Muscle Skeletal Muscle Use the following information to answer the next two questions. Normally, skeletal muscle contractions are stimulated and controlled by nerve cells. Calcium ions (Ca2+) also play an important role in the way muscles are controlled, as demonstrated by a series of experiments using isolated muscle fibres. These fibres can be manipulated in various ways: They can be stimulated with electrodes to mimic the effect of nerve cells. Ca2+ in solution can be injected into the fibres. A chemical that removes Ca2+ already present in the fibres can be injected. The results from experiments using these procedures are given in the table below. The Effect of Calcium Ions on Muscle Fibre Contraction Experiment Procedures Results Electrode Stimulation Ca2+ injected or removed 1 on neither contraction 2 off injected contraction 3 on removed no contraction 1. Interpret the results of these experiments. 2. What evidence is there from these experiments that calcium ions are normally present in muscle tissue? Use the following additional information to answer the next four questions. Additional experiments using injections of radioactive Ca2+ show that the ions are stored within the sacs of the sarcoplasmic reticulum in resting muscle tissue. When the tissue is stimulated to contract with electrodes, the radioactive Ca2+ ions are found among the actin and myosin filaments as shown below. 3. Refer to diagram of the muscle at rest above, and explain what effect a lack of tropomyosin would have in muscle tissue. 4. The diagram of the muscle contracting shows the role of calcium ions in repositioning tropomyosin. Where are these ions stored when the muscle is at rest? What causes them to move among the actin and myosin filaments? 5. What happens to calcium ions and tropomyosin to cause a muscle to relax? 6. Use a flow chart to describe the series of events that starts with stimulation and ends with relaxation. Once energy from ATP and creatine phosphate stored in working muscle fibers is exhausted, ATP is generated from the breakdown of glucose and fatty acids through aerobic and anaerobic respiratory pathways. To keep contracting, the muscle increases aerobic cellular respiration and carries out fermentation as oxygen becomes scarce. In the contracting muscle, ATP is broken down to ADP + P as energy is spent on movement and heat is released. 1. Explain how red muscle is well adapted to accommodate a high rate of cellular respiration. 2. Involuntary shivering occurs when body temperature decreases. Why is this response an advantage for survival? 3. Recalling your knowledge of the circulatory system, explain how wasted heat from strenuous exercise is dissipated from the body. 4. In fermentation, ATP is generated without oxygen. It may seem that this involves getting something for nothing. Is this true? Explain.