Muscular System Study Guide KEY PDF

Name: KEY Muscular System – Study Guide Types of Muscle Tissue Fill in A for skeletal muscle tissue, B for cardiac muscle tissue, and C for smooth muscle tissue. For some questions you will select multiple answers. 1. B Cells branch and interconnect...

Name: KEY Muscular System – Study Guide Types of Muscle Tissue Fill in A for skeletal muscle tissue, B for cardiac muscle tissue, and C for smooth muscle tissue. For some questions you will select multiple answers. 1. B Cells branch and interconnect 14. C Found in intestines & stomach 2. B, C Cells: central nuclei 15. C Found in uterus & vas deferens 3. A Cells: multinucleated 16. C Job: causes blushing 4. B, C Cells: one nucleus 17. A Job: causes movements such as kicking, running, or walking 5. A Cells: peripheral nuclei 18. C Job: contractions during birth 6. A, B Cells: striated 19. A Job: creating body heat 7. C Completely involuntary control 20. C Job: digestion 8. A Completely voluntary control 21. A Job: maintains our posture when sitting 9. A Ex. Biceps brachii and walking 10. A Found attached to bones and sometimes 22. B Job: pumping blood through blood skin vessels 11. C Found in urinary bladder 23. B Mainly involuntary control 12. C Found in eye & blood vessels 24. C Slow contractions (called peristalsis 13. B Found in heart Characteristics of Muscle Tissue Fill in A for excitability, B for contractility, C for extensibility, and D for elasticity. For some questions you will select multiple answers. 1. C Muscle’s ability to be stretched without tearing 2. B Muscle’s ability to shorten 3. A Muscle’s ability to respond to stimuli, such as an action potential from a motor neuron 4. D Muscle’s ability to return to its original shape after contracting or relaxing 5. D Example: After doing a split, a gymnast’s muscles return to their original shape. 6. B Example: As you lift a weight over your head, your triceps muscle shortens. 7. A Example: Your brain sends a message to your hamstrings to contract. Your hamstrings respond. 8. D Example: When you are finish lifting weights, your muscles do not stay in that contracted state, but go back to their original shape and size. 9. C Example: You stretch before your cross-country race and your muscles do not tear. 10. A Example: When Luigi Galvani hooked frogs up to electricity their muscles contracted. 11. B Example: Your intestines do peristalsis, which causes them to shorten as they push food through themselves. 12. D Example: Every 0.7 seconds your heart contracts. When it is done contracting, it goes back to its resting state. Structure of a Skeletal Muscle 1. A muscle cell is also known as a muscle fiber. 2. What type of tissue connects muscle tissue to a bone? Tendon 3. Which is the largest? Muscle fiber, myofibril, fascicle Fascicle 4. Which is the largest? Sarcomere, myofilament, myofibril Myofibril 5. Which is the largest? Myofilament, muscle fiber, sarcomere Muscle fiber 6. Which is the smallest? Muscle fiber, muscle, fascicle Muscle fiber 7. Which is the smallest? Muscle fiber, sarcomere, myofibril Sarcomere 8. Which is the smallest? Sarcomere, fascicle, myofilament Myofilament 9. A muscle is made of many fascicles (one subunit down from a muscle). 10. A muscle fiber is made of many myofibrils (one subunit down from a muscle fiber). 11. A myofibril is made of many sarcomeres (one subunit down from a myofibril). 12. A fascicle is made of many muscle fibers (one subunit down from a fascicle). 13. A sarcomere is made of many myofilaments (one subunit down from a sarcomere). 14. What are the two myofilaments? Actin & myosin 15. Which myofilament is thick? Myosin 16. Which myofilament is thin? Actin 17. Together, actin and myosin make up a sarcomere. 18. A muscle is wrapped in a CT sheath called a/an epimysium. 19. A fascicle is wrapped in a CT sheath called a/an perimysium. 20. A muscle fiber is wrapped in a CT sheath called a/an endomysium. 21. A group of fascicles is a muscle. 22. A group of myofibrils is a muscle fiber. 23. A group of muscle fibers is a fascicle. 24. When a muscle contracts the smallest part that contracts is a sarcomere. Skeletal Muscle Anatomy 1. Tendon 2. Muscle 3. Fascicle 4. Muscle fiber 5. Myofibril 6. Epimysium 7. Perimysium 8. Endomysium 9. Sarcomere 10. Actin 11. Myosin 12. Myofilaments Neuromuscular Junction 1. Each muscle fiber is made of smaller, long and skinny proteins called myofibrils. 2. A muscle fiber, like all cells, has smaller subparts (ex. Nucleus) called organelles. 3. The cell membrane of a muscle fiber is called the sarcolemma. 4. Receptors are the binding sites on the outside of a muscle fiber that receive neurotransmitters. 5. T-tubules are the parts of the sarcolemma that penetrate deep into the interior of a muscle fiber. 6. Why is it important that the T-tubules penetrate deep into the muscle fiber interior? This allows the action potential to reach the deepest parts of the sarcoplasmic reticulum, causing a stronger contraction. 7. The sarcoplasmic reticulum regulates levels of Ca2+ ions inside a muscle fiber. 8. What happens when an electrical impulse reaches the sarcoplasmic reticulum? What happens to the muscle fiber because of this? The sarcoplasmic reticulum releases Ca2+ ions into the muscle fiber, causing the muscle fiber to contract. 9. What happens when there is no electrical impulse entering the sarcoplasmic reticulum? What happens to the muscle fiber because of this? The sarcoplasmic reticulum does not release Ca2+ ions into the muscle fiber, so the muscle fiber relaxes.  10. Label the following skeletal muscle fiber using the following terms and arrows: axon terminal, myofibril, neurotransmitters, receptors, sarcolemma, sarcoplasmic reticulum, T-tubule Receptors Axon terminal Neurotransmitters Sarcoplasmic reticulum Sarcolemma T-tubule Myofibril 11. Another word for the electrical message that passes through neurons and to muscle fibers is an action potential. 12. The fact that muscles respond to these electrical impulses reflects this characteristic of muscle tissue: excitability. 13. The neuromuscular junction is the location where a motor neuron and a skeletal muscle fiber come together. 14. Which type of neurons carry action potentials from the brain to skeletal muscle fibers? Motor neuron 15. Neurons are long cells. The specific part of a neuron that meets with a skeletal muscle fiber is known as the axon terminal. 16. True or False: The motor neuron and muscle fiber directly touch. False 17. The space between the motor neuron and muscle fiber is referred to as the synaptic cleft. 18. Because a motor neuron and muscle fiber do not physically touch, axon terminals release chemical messages to bridge the synaptic cleft. These chemical messages are known as neurotransmitters. 19. The specific neurotransmitter that is released by the axon terminal at a neuromuscular junction is called acetylcholine. 20. The release of acetylcholine triggers a skeletal muscle fiber to contract (contract or relax)? Neuromuscular Junction Essay Be prepared for an essay question regarding the neuromuscular junction on your test. In the space below, practice writing what happens to cause a muscle to contract (starting with the brain deciding to contract the muscle, finishing with the muscle contracting). Points on the essay will be lost for missing important steps and details. For a skeletal muscle fiber to contract, the brain must first decide that it wants the skeletal muscle to contract. The brain sends an action potential through motor neurons down the spinal cord towards the direction of the skeletal muscle. The action potential travels through nerves until it reaches the skeletal muscle fiber at the neuromuscular junction. The action potential triggers the axon terminal of the motor neuron to release acetylcholine into the synaptic cleft. The acetylcholine binds to receptors on the sarcolemma, or skeletal muscle fiber cell membrane. The binding of acetylcholine causes the action potential to travel along the action potential and down the T-tubules of the muscle fiber. Within the T-tubules, the action potential branches off and stimulates the sarcoplasmic reticulum to release Ca2+ ions. These ions trigger the muscle fiber to contract. ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ Structure of a Sarcomere 1. What is the smallest unit of a muscle to contract? sarcomere 2. Actin is the thin myofilament. Myosin is the thick myofilament. Myosin has “hands” that bind to actin. 3. Which myofilament looks like two strands of pearls? Actin 4. Which myofilament is attached to the Z line? Actin 5. Which part of a sarcomere contains only thick filaments? H zone 6. Which part of a sarcomere contains only thin filaments? I band 7. Which part of the sarcomere is the boundary between sarcomeres? Z line 8. Which part of the sarcomere contains both actin and myosin? A band 9. Which part of the sarcomere is the line down the middle of myosin? M line  10. Which part of the sarcomere runs the entire length of myosin? A band 11. Which part of the sarcomere is the dark band? A band 12. Which part of the sarcomere is the light band? I band 13. Which myofilament pulls the other when a muscle contracts? Myosin 14. True or False: When a sarcomere contracts, actin & myosin stay the same length. True 15. What is needed for myosin to be able to grab and pull actin? Ca2+ ions 16. What happens to the I band when a sarcomere goes from relaxed to contracted? The I band shortens and disappears. 17. What happens to the Z lines when a sarcomere goes from relaxed to contracted? The Z lines get closer together. 18. What happens to the A band when a sarcomere goes from relaxed to contracted? The A band does not change at all. 19. What happens to the H zone when a sarcomere goes from relaxed to contracted? The H zone shortens and disappears. 20. True or False: When a sarcomere contracts, actin moves further away from the M line. False 21. True or False: When a sarcomere contracts, myosin moves closer to the Z line. True 22. Label the following sarcomere using brackets and the following labels: A band, H zone, I bands, Z lines, M line, actin, myosin. If one band or zone appears twice, label it twice. A band I band I band H zone M line Myosin Z line Actin Structure of Myofilaments 1. What are the two myofilaments? Actin & myosin 2. Together, myofilaments make up a sarcomere. 3. Do the myofilaments themselves shorten when a muscle contracts? no 4. Which myofilament has “hands” to grab the other? Myosin 5. Which myofilament is attached to the Z line? Actin 6. Which myofilament looks like two strands of pearls? Actin 7. Which myofilament is powered by ATP? Myosin 8. Tropomyosin is attached to the actin myofilament. 9. Troponin is attached to the actin myofilament. 10. Which regulatory protein is rod-like and runs the length of actin? Tropomyosin 11. Which regulatory protein blocks myosin binding sites on actin? Tropomyosin 12. Which regulatory protein blocks actin binding sites on myosin? None (these aren’t a thing!) 13. Which regulatory protein has a binding site for calcium ions? Troponin 14. Which regulatory protein stiffens actin so it doesn’t flop over? Tropomyosin 15. Which regulatory protein has 3 binding sites? Troponin 16. Which regulatory protein can move the other one? Troponin 17. What happens when calcium binds to troponin? Troponin changes shape and rolls tropomyosin off the myosin binding sites. 18. Once the myosin binding sites are uncovered, what does myosin for “power” to allow it to cock up and bind? ATP 19. With both ATP and calcium present, what can happen? Myosin heads are able to bind to the myosin binding sites, forming a cross-bridge (so that the sarcomere can contract). 20. When ATP and calcium are absent, what happens to the sarcomere? Myosin heads cannot bind to the myosin binding sites (so the sarcomere is relaxed). 21. Why does the sarcomere relax when calcium is absent? Be specific. The myosin-binding sites are covered up by tropomyosin. 22. Why does the sarcomere relax when ATP is absent? Be specific. The myosin heads are unable to cock up and attach. 23. Circle the picture that shows a contracted sarcomere.  24. Label the following myofilaments using the following labels: actin, myosin, myosin head, calcium, myosin binding sites, tropomyosin, troponin. Troponin Calcium Tropomyosin Actin Myosin head Myosin binding sites Myosin Cross-Bridge Cycling 1. Which happens first: cross-bridge cycling OR delivery of an action potential at the neuromuscular junction. Action potential at the neuromuscular junction 2. A cross-bridge is where which two things meet? Myosin heads & myosin binding sites 3. A cross-bridge can only form when ATP and Ca2+ ions are present. 4. Which myofilament pulls the other one, causing a sarcomere to shorten? Myosin 5. Put the following steps of cross-bridge cycling in order: D, C, F, G, B, A, E a. ATP binds to myosin, allowing it to break the cross-bridge. b. Myosin pulls actin toward the M-line. This movement is known as the power stroke. c. Ca2+ binds to troponin molecules on actin. d. Ca2+ ions are released by the sarcoplasmic reticulum. e. The process repeats as long as both Ca2+ and ATP are present. f. The binding of Ca2+ causes troponin to change shape, triggering it to roll tropomyosin away from the myosin binding sites, exposing them. g. The myosin head cocks, forming a cross-bridge between the myosin head and myosin binding site. Muscle Fiber Types (from the muscle fatigue lab) 1. What are the two types of muscle fibers? Fast-twitch & slow-twitch 2. True or False: All athletes have equal amounts of both fiber types. False 3. True or False: The more you work one type of fiber, the more dominant it becomes. True 4. Which type of muscle fiber do sprinters work? Fast-twitch 5. Which type of muscle fiber do marathon runners work? Slow-twitch  6. Fill in the chart below, writing a check mark for the correct type of muscle fiber. Trait Fast twitch Slow twitch Great for endurance X Great for powerful bursts X Contract quickly (for short periods of time) X Contract slowly (for long periods of time) X Grow more easily X Have myoglobin X Lack myoglobin X Red X White X Have oxygen available X Lack oxygen X Must use anaerobic respiration X Use aerobic respiration X Fatigues more quickly X Fatigues less quickly X Types of Respiration (from the muscle fatigue lab) 1. Which type of respiration is better for endurance? Aerobic 2. Which type of respiration is better for powerful bursts? Anaerobic 3. Why is aerobic respiration aerobic? Why is anaerobic respiration anaerobic? Remember that the root word “an” means “not. What does anaerobic respiration “not” have? Aerobic respiration uses oxygen. Anaerobic respiration occurs without oxygen. 4. Which type of respiration produces more ATP? How much ATP does each type of respiration produce? Aerobic respiration makes more ATP (38 per cycle). Anaerobic respiration only makes 2. 5. Which type of respiration produces lactic acid? What does lactic acid cause? Anaerobic respiration produces lactic acid, which causes the burn. 6. Why does fatigue happen more quickly when using anaerobic respiration? Fatigue happens due to a lack of oxygen and ATP. Anaerobic respiration lacks oxygen and produces low amounts of ATP. Lactic acid also causes fatigue. 7. You are taking a 5-mile walk. Which type of respiration are you using? Aerobic 8. You are lifting weights. Which type of respiration are you using? Anaerobic