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Chapter 7: The Muscular System 1. A) B) C) D) Ans: Which surrounds a fascicle? endomysium epimysium fascia perimysium D 2. A) B) C) D) Ans: Myofibrils are located in muscle fibers. are contractile units. have striations. are described by all of these characteristics. D 3. A) B) C) D) Ans: Myosin is a protein. the thin filament. pulled inward during contraction. described by all of these characteristics. A 4. A) B) C) D) Ans: Lactic acid buildup occurs after strenuous activity. occurs due to lack of oxygen. causes cramps. is described by all of these characteristics. D 5. A) B) C) Ans: Which obeys the all-or-none law? the whole muscle a muscle fiber the whole muscle and a muscle fiber B 6. A) B) C) Ans: Which is on the stationary bone? insertion prime mover origin C Page 52 7. A) B) C) Ans: Fatigue is receiving many impulses in rapid succession. the period between stimulation and contraction. the depletion of ATP. C 8. A) B) C) Ans: Summation is receiving many impulses in rapid succession. the period between stimulation and contraction. the depletion of ATP. A 9. A) B) C) Ans: Latent period is receiving many impulses in rapid succession. the period between stimulation and contraction. the depletion of ATP. B 10. A) B) C) D) Ans: Adduction is movement of body part toward midline. decreasing the joint angle. movement around an axis. circumduction. A 11. A) B) C) D) Ans: Rotation is movement of body part toward midline. decreasing the joint angle. movement around an axis. circumduction. C 12. A) B) C) D) Ans: Flexion is movement of body part toward midline. decreasing the joint angle. movement around an axis. circumduction. B 13. A) B) C) D) Ans: Movement in a wide circle is movement of body part toward midline. decreasing the joint angle. movement around an axis. circumduction. D Page 53 figure 7.1 14. Which letter in figure 7.1 points to the origin? Ans: a 15. Which letter in figure 7.1 points to the insertion? Ans: b 16. A) B) C) Ans: The biceps and triceps in figure 7.1 are antagonistic. are synergistic. depend upon activity to determine antagonism or synergism. A 17. A) B) C) Ans: During which type of contraction does movement occur? isometric isotonic isometric and isotonic B Page 54 figure 7.2 18. Which letter in figure 7.2 points to the masseter? Ans: b 19. Which letter in figure 7.2 points to the pectoralis major? Ans: a 20. Which letter in figure 7.2 points to the sartorius? Ans: d 21. Which letter in figure 7.2 points to the gastrocnemius? Ans: c figure 7.3 Page 55 22. Which letter in figure 7.3 points to the latissimus dorsi? Ans: d 23. Which letter in figure 7.3 points to the trapezius? Ans: b 24. Which letter in figure 7.3 points to the external oblique? Ans: a 25. Which letter in figure 7.3 points to the deltoid? Ans: c figure 7.4 26. Which letter in figure 7.4 points to the rectus abdominus? Ans: a 27. Which letter in figure 7.4 points to the sternocleidomastoid? Ans: d 28. Which letter in figure 7.4 points to the internal oblique? Ans: c 29. A) B) C) D) Ans: The __________ raises your eyebrow. biceps brachii frontalis hamstring group gluteus maximus B Page 56 30. A) B) C) D) Ans: The __________ extends your thigh. biceps brachii frontalis hamstring group gluteus maximus D 31. A) B) C) D) Ans: The __________ flexes your elbow. biceps brachii frontalis hamstring group gluteus maximus A 32. A) B) C) D) Ans: The __________ flexes your leg. biceps brachii frontalis hamstring group gluteus maximus C 33. What are the sources of ATP for muscle contraction? Ans: 1. Produced in the mitochondria via aerobic cellular respiration. 2. Regenerated by creatine phosphate. 3. Produced via anaerobic respiration. 34. What is the reason for lactic acid buildup and how is it removed? Ans: Lactic acid is an end product of anaerobic respiration. It is removed by deep breathing following exercise, which supplies the oxygen required to metabolize the lactic acid. 35. What effect does lack of exercise have on muscle tissue? Ans: Forceful contractions of muscles cause them to increase in size while lack of contractions or weak contractions cause them to decrease in size. 36. Muscle fatigue is usually due to lactic acid accumulation in the muscles. How and why does this happen? Ans: When muscle fibers fatigue, they have run out of ATP. Lactic acid builds up as a result of anaerobic respiration and produces muscle aching and fatigue. 37. When chewing a piece of gum, what muscles would you use? Ans: The masseter and temporalis muscles mainly. The buccinator muscle would help hold the gum in contact with the teeth. Page 57 38. Distinguish between epimysium, perimysium, and endomysium. Ans: Epimysium - connective tissue covering an entire muscle (fascia) Perimysium - connective tissue surrounding fascicles (bundles of muscle fibers within a muscle) Endomysium - connective tissue surrounding individual muscle fibers (cells) within a fascicle 39. What is meant by oxygen debt? Ans: When there is insufficient oxygen available to generate ATP aerobically, anaerobic respiration will commence. Lactic acid is a product of anaerobic respiration that causes muscle fatigue and pain. Following strenuous exercise we must continue to breathe deeply in order to supply the oxygen required to metabolize the lactic acid that has built up in our cells. This oxygen represents an oxygen debt that must be repaid following anaerobic respiration. 40. If muscle fibers obey the all-or-none law, then how can muscles exhibit various strengths of contraction? Ans: Muscles can exhibit various strengths of contraction because different numbers of fibers can be contracting during muscle contraction. When more muscle fibers are contracting the whole-muscle contraction is of greater strength. When few muscle fibers are contracting the whole-muscle contraction is of lesser strength. 41. List and discuss benefits of exercise. Ans: See Medical Focus in text. 42. Arrange the following terms in order from smallest to largest: fascicle, muscle, muscle fiber, myofibril, myofilament. Ans: myofilament, myofibril, muscle fiber, fascicle, muscle. 43. Give one example each for isometric and isotonic contraction. Ans: Answers may vary, but isometric contraction will not result in the shortening of a muscle while isotonic contraction will. 44. List, in order, the three components of a single muscle twitch. Ans: Latent period, contraction period, relaxation period. 45. Describe the relationship between summation and tetanus. Ans: When a muscle receives numerous stimuli in succession, the force of the muscle contraction will increase until it reaches a maximum level. The maximal sustained contraction that occurs is called tetanus. Page 58 46. A) B) C) D) Ans: Which muscle tissue type has intercalated disks? cardiac skeletal smooth Both cardiac and skeletal are correct. A 47. A) B) C) D) Ans: Which muscle tissue type is striated? cardiac skeletal smooth Both cardiac and skeletal are correct. D 48. A) B) C) D) Ans: A sarcomere is formed from myosin only. the distance between Z lines. the length of the H zone. between the I bands. B 49. A) B) C) D) Ans: What does calcium do during muscle contraction? binds to troponin binds to the crossbridges supplies energy hydrolyzes ATP A Page 59