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| 1 | |
Which of these is true of skeletal muscle? |
| | A) | spindle-shaped cells |
| | B) | under involuntary control |
| | C) | many peripherally located nuclei per muscle cell |
| | D) | forms the walls of hollow internal organs |
| | E) | may be autorhythmic |
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| 2 | |
Which of these is not a major functional characteristic of muscle? |
| | A) | contractility |
| | B) | elasticity |
| | C) | excitability |
| | D) | extensibility |
| | E) | secretability |
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| 3 | |
The connective tissue sheath that surrounds a muscle fasciculus is the |
| | A) | perimysium. |
| | B) | endomysium. |
| | C) | epimysium (fascia). |
| | D) | hypomysium. |
| | E) | external lamina. |
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| 4 | |
Given these structures:
1. whole muscle
2. muscle fiber (cell)
3. myofilament
4. myofibril
5. muscle fasciculus
Choose the arrangement that lists the structures in the correct order from the largest to the smallest structure. |
| | A) | 1,2,5,3,4 |
| | B) | 1,2,5,4,3 |
| | C) | 1,5,2,3,4 |
| | D) | 1,5,2,4,3 |
| | E) | 1,5,4,2,3 |
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| 5 | |
Each myofibril |
| | A) | is made up of many muscle fibers. |
| | B) | contains sarcoplasmic reticulum. |
| | C) | is made up of many sarcomeres. |
| | D) | contains T tubules. |
| | E) | is the same thing as a muscle fiber. |
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| 6 | |
Myosin myofilaments are |
| | A) | attached to the Z disk. |
| | B) | found primarily in the I band. |
| | C) | thinner than actin myofilaments. |
| | D) | absent from the H zone. |
| | E) | attached to filaments that form the M line. |
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| 7 | |
Which of these statements about the molecular structure of myofilaments is true? |
| | A) | Tropomyosin has a binding site for Ca2+. |
| | B) | The head of the myosin molecule binds to an active site on G actin. |
| | C) | ATPase is found on troponin. |
| | D) | Troponin binds to the rodlike portion of myosin. |
| | E) | Actin molecules have a hingelike portion that bends and straightens during contraction. |
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| 8 | |
The part of the sarcolemma that invaginates into the interior of the skeletal muscle cells is the |
| | A) | T tubule system. |
| | B) | sarcoplasmic reticulum. |
| | C) | myofibrils. |
| | D) | terminal cisternae. |
| | E) | mitochondria. |
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| 9 | |
During the depolarization phase of an action potential, the permeability of the plasma membrane to |
| | A) | Ca2+ increases. |
| | B) | Na+ increases. |
| | C) | K+ increases. |
| | D) | Ca2+ decreases. |
| | E) | Na+ decreases. |
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| 10 | |
During depolarization, the inside of the membrane |
| | A) | becomes more negative than the outside of the membrane. |
| | B) | becomes more positive than the outside of the membrane. |
| | C) | is unchanged. |
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| 11 | |
During repolarization of the plasma membrane, |
| | A) | Na+ move to the inside of the cell. |
| | B) | Na+ move to the outside of the cell. |
| | C) | K+ move to the inside of the cell. |
| | D) | K+ move to the outside of the cell. |
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| 12 | |
Given these events:
1. acetylcholine broken down into acetic acid and choline
2. acetylcholine moves across the synaptic cleft
3. action potential reaches the terminal branch of the motor neuron
4. acetylcholine combines with a receptor molecule
5. action potential is produced on the muscle fiber’s plasma membrane
Choose the arrangement that lists the events in the order they occur at a neuromuscular junction. |
| | A) | 2,3,4,1,5 |
| | B) | 3,2,4,5,1 |
| | C) | 3,4,2,1,5 |
| | D) | 4,5,2,1,3 |
| | E) | 5,1,2,4,3 |
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| 13 | |
Acetylcholinesterase is an important molecule in the neuromuscular junction because it |
| | A) | stimulates receptors on the presynaptic terminal. |
| | B) | synthesizes acetylcholine from acetic acid and choline. |
| | C) | stimulates receptors within the postsynaptic membrane. |
| | D) | breaks down acetylcholine. |
| | E) | causes the release of Ca2+ from the sarcoplasmic reticulum. |
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| 14 | |
Given these events:
1. sarcoplasmic reticulum releases Ca2+
2. sarcoplasmic reticulum takes up Ca2+
3. Ca2+ diffuse into myofibrils
4. action potential moves down the T tubule
5. sarcomere shortens
6. muscle relaxes
Choose the arrangement that lists the events in the order they occur following a single stimulation of a skeletal muscle cell. |
| | A) | 1,3,4,5,2,6 |
| | B) | 2,3,5,4,6,1 |
| | C) | 4,1,3,5,2,6 |
| | D) | 4,2,3,5,1,6 |
| | E) | 5,1,4,3,2,6 |
| | F) | 4,1,3,5,2,6 |
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| 15 | |
Given these events:
1. Ca2+ combine with tropomyosin
2. Ca2+ combine with troponin
3. tropomyosin pulls away from actin
4. troponin pulls away from actin
5. tropomyosin pulls away from myosin
6. troponin pulls away from myosin
7. myosin binds to actin
Choose the arrangement that lists the events in the order they occur during muscle contraction. |
| | A) | 1,4,7 |
| | B) | 2,5,6 |
| | C) | 1,3,7 |
| | D) | 2,4,7 |
| | E) | 2,3,7 |
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| 16 | |
Which of these regions shortens during skeletal muscle contraction? |
| | A) | A band |
| | B) | I band |
| | C) | H zone |
| | D) | both a and b |
| | E) | both b and c |
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| 17 | |
With stimuli of increasing strength, which of these is capable of a graded response? |
| | A) | nerve axon |
| | B) | muscle fiber |
| | C) | motor unit |
| | D) | whole muscle |
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| 18 | |
Considering the force of contraction of a skeletal muscle cell, multiple-wave summation occurs because of |
| | A) | increased strength of action potentials on the plasma membrane. |
| | B) | a decreased number of cross-bridges formed. |
| | C) | an increase in Ca2+ concentration around the myofibrils. |
| | D) | an increased number of motor units recruited. |
| | E) | increased permeability of the sarcolemma to Ca2+. |
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| 19 | |
Which of these events occurs during the lag (latent) phase of muscle contraction? |
| | A) | cross-bridge movement |
| | B) | active transport of Ca2+ into the sarcoplasmic reticulum |
| | C) | Ca2+ bind to troponin |
| | D) | the sarcomere shortens |
| | E) | ATP is broken down to ADP |
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| 20 | |
A weight lifter attempts to lift a weight from the floor, but the weight is so heavy he is unable to move it. The type of muscle contraction the weight lifter used was mostly |
| | A) | isometric. |
| | B) | isotonic. |
| | C) | isokinetic. |
| | D) | concentric. |
| | E) | eccentric. |
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| 21 | |
An active tension curve illustrates |
| | A) | how isometric contractions occur. |
| | B) | that the greatest force of contraction occurs if a muscle is not stretched at all. |
| | C) | that passive tension can create active tension. |
| | D) | that optimal overlap of actin and myosin produces the greatest force of contraction. |
| | E) | that the greatest force of contraction occurs with little or no overlap of actin and myosin. |
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| 22 | |
Which of these types of fatigue is the most common? |
| | A) | muscular fatigue |
| | B) | psychologic fatigue |
| | C) | synaptic fatigue |
| | D) | army fatigue |
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| 23 | |
Given these conditions:
1. low ATP levels
2. little or no transport of Ca2+ into the sarcoplasmic reticulum
3. cross-bridges release
4. Na+ accumulate in the sarcoplasm
5. cross-bridges form
Choose the conditions that occur in both physiologic contracture and rigor mortis. |
| | A) | 1,2,3 |
| | B) | 1,2,5 |
| | C) | 1,2,3,4 |
| | D) | 1,2,4,5 |
| | E) | 1,2,3,4,5 |
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| 24 | |
Jerry Jogger’s 3 mile run every morning takes about 30 minutes. Which of these sources provides most of the energy for his run? |
| | A) | aerobic respiration |
| | B) | anaerobic respiration |
| | C) | creatine phosphate |
| | D) | stored ATP |
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| 25 | |
Which of these conditions would one expect to find within the leg muscle cells of a world-class marathon runner? |
| | A) | myoglobin-poor |
| | B) | contract very quickly |
| | C) | primarily anaerobic |
| | D) | numerous mitochondria |
| | E) | large deposits of glycogen |
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| 26 | |
Which of these increases the least as a result of muscle hypertrophy? |
| | A) | increase in number of sarcomeres |
| | B) | increase in number of myofibrils |
| | C) | increase in number of fibers |
| | D) | increase in blood vessels and mitochondria |
| | E) | increase in connective tissue |
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| 27 | |
Relaxation in smooth muscle occurs when |
| | A) | myosin kinase attaches phosphate to the myosin head. |
| | B) | Ca2+ bind to calmodulin. |
| | C) | myosin phosphatase removes phosphate from myosin. |
| | D) | Ca2+ channels open. |
| | E) | Ca2+ are released from the sarcoplasmic reticulum. |
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| 28 | |
Compared to skeletal muscle, visceral smooth muscle |
| | A) | has the same ability to be stretched. |
| | B) | when stretched, loses the ability to contract forcefully. |
| | C) | maintains about the same tension, even when stretched. |
| | D) | cannot maintain long, steady contractions. |
| | E) | can accumulate a substantial oxygen debt. |
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| 29 | |
Which of these often have spontaneous contractions? |
| | A) | multiunit smooth muscle |
| | B) | visceral smooth muscle |
| | C) | skeletal muscle |
| | D) | both a and b |
| | E) | both b and c |
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| 30 | |
Which of these statements concerning aging and skeletal muscle is correct? |
| | A) | There is a loss of muscle fibers with aging. |
| | B) | Slow-twitch fibers decrease in number faster than fast-twitch fibers. |
| | C) | Loss of strength and speed is mainly due to loss of neuromuscular junctions. |
| | D) | There is an increase in density of capillaries in skeletal muscle. |
| | E) | The number of motor neurons remains constant. |
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