74) Which statement about excitation-contraction coupling is incorrect? A) Calcium ion is released from the transverse tubule. 75) The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n) C) twitch. 76) Calcium ions are bound to troponin during which of the following steps. B) contraction phase 77) The synchronous contraction of a single motor unit is known as a(n) D) fasciculation. 78) When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the amount of tension gradually increases to a steady maximum tension. This is called B) complete tetanus.
79) A muscle producing tension that peaks but falls to only intermediate stimulus rates is said to be in A) incomplete tetanus. 80) If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called D) wave summation. 81) A single motor neuron together with all the muscle fibers it innervates is called a(n) C) motor unit. 82) The increase in muscle tension that is produced by increasing the number of active motor units is called E) recruitment. 83) Muscular force can be adjusted to match increased loads by A) increasing the frequency of action potentials in motor neurons. 84) In which of the following would the motor units have the fewest muscle fibers? C) muscles that control the eyes 85) Which of the following muscles would contract more forcefully? B) a muscle receiving 20 to 25 action potentials per second 86) Which of the following motor units would produce the greatest tension? A) a motor unit in a back muscle Figure 9-2
87) To produce a contraction similar to the one in graph (b), the muscle B) must be stimulated again before it has relaxed from the previous stimulation. 88) Why is there partial relaxation in graph (c)? E) Maximum tension is below maximum. 89) What is the contraction in graph (d) called? A) complete tetanus 90) What is thought to happen in a muscle during the response shown in graph (a)? B) There is a gradual increase in the concentration of calcium ions in the sarcoplasm. 91) The type of contraction in which the muscle fibers do not shorten is called E) isometric. 92) In an isotonic contraction, A) muscle tension exceeds the load and the muscle lifts the load. 93) Which of the following is not true of the muscular system? A) It depends upon calcium stored and released from the skeletal system. B) It depends upon calcitonin and parathyroid hormone levels to maintain calcium homeostasis. C) It depends upon the integumentary system to protect muscles. D) It depends upon the cardiovascular system to provide the hemoglobin stored in slow muscle fibers. E) It depends upon the nervous system to stimulate skeletal muscle tissue to contract. 94) A resting muscle generates most of its ATP by D) glycogenolysis.
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- Fall '13
- Anatomy, muscle weakness, muscle tension, increased muscle mass