Anatomy and Physiology

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Section I – Multiple choice: (65 points; 2.5 points each). Bubble your answers on your scantron. 1. A motor unit refers to
a. a single muscle fiber plus all of the motor neurons that innervate it b. all of the motor neurons supplying a single muscle
c. *a single motor neuron plus all the muscle fibers it innervates d. a pair of antagonistic muscles
e. all of the muscles that affect the movement of any given joint

2. Which of the following is NOT associated with the thin filaments in skeletal muscle: a. tropomyosin
b. *titin
c. actin
d. troponin
e. nebulin

3. What produces the symptoms of rigor mortis following death? a. the storage vesicles for ATP begin to break down at death, leading to the release of ATP and persistent contraction of the skeletal muscles b. *skeletal muscles can no longer produce ATP, so the myosin heads can no longer dissociate from actin filaments c. since skeletal muscles can no longer produce ATP, myosin cannot bind to actin so the muscles are frozen in position (actin and myosin unbound) d. the actin an myosin proteins are broken down so there can be no muscle contraction

4. To encode a stimuli of greater intensity the sensory system a. Fires increased frequency of action potentials
b. Increases the recruitment of additional sensory neurons c. Generates a longer series of action potentials
d. *A and B
e. A, B and C.

5. Place the following levels of muscle organization from largest to smallest: 1. myofibrils
2. sarcomere
3. skeletal muscle
4. muscle fiber
5. muscle fascicle
a. *3, 5, 4, 1, 2
b. 1, 4, 5, 3, 2
c. 3, 4, 5, 1, 2
d. 5, 3, 1, 2, 4
e. none of the above are correct order.

6. Which of the following statements about skeletal muscle structure is true? a. thin filaments are composed mostly of myosin proteins
b. skeletal muscle appears striated under a light microscope because of repeating units called sarcomas. c. myosin’s tail region is important because it contains binding sites for actin d. titin and nebulin are regulatory proteins that can impact myosin’s interaction with actin e. *none of the above

7. Fast oxidative fibers:
a. have more mitochondria than fast glycolytic fibers
b. have faster myosin ATPase activity, compared to slow oxidative fibers c. have more myoglobin compared to fast glycolytic muscle fibers d. are specialized for generating ATP from glucose through oxidative pathways e. *all of the above

8. Which of the following statements is true?
a. As the sarcomere shortens, the two Z disks at each end move closer together, and the I band and H zone become smaller. b. The thin actin filaments slide along the thick myosin filaments as they move toward the M line in the center of the sarcomere. c. The A-Band shortens.

d. *A and B
e. A, B, and C

9. Which of the following statements about muscle contractions is false? a. In muscles used for fine actions, such as the use of the hand, a motor unit will have fewer muscle fibers than when compared to a motor unit in muscles used for power and strength b. All muscle fibers in a single motor unit are of the same fiber type. c. The entire skeletal muscle contracts in an all-or-none manner. d. The brief period of time between the end of the action potential in the muscle fiber and the beginning of contraction is referred to as twitch e. *c and d

10. Which of the following statements about the neuromuscular junction is false? a. *the neuromuscular junction is located towards the end of the muscle cell and results in an action potential that spreads in all directions. b. the modified plasma membrane of a muscle cell at the neuromuscular junction are motor end plates. c. a single action potential arriving at the motor end plate typically results in the generation of...
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