Q. No.A decrease in the mass of the muscle most commonly experienced when persons suffer temporary disabling circumstances is called as:
1. hypertrophy
2. atrophy
3. dystrophy
4. peristalsis
A neuromuscular disorder that causes weakness in the skeletal muscles is:
| 1. | poliomyelitis | 2. | myasthenia gravis |
| 3. | multiple sclerosis | 4. | muscular dystrophy |
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Immediately after the motor neuron passes an impulse to a muscle fiber:
1. the impulse travels over the sarcolemma in all directions.
2. calcium is released from the sarcoplasmic reticulum.
3. cross bridge forms between the actin and myosin.
4. troponin undergoes a conformational change.
Identify the incorrect statement:
1. A muscle fiber contracts in an all-or-none fashion.
2. A slight delay occurs between the reaching of impulse at the neuromuscular junction and muscle contraction.
3. Using more motor units will increase the overall force of contraction.
4. When a person is fully at rest, none of her muscles are contracting.
Identify the incorrect statement regarding a skeletal muscle fiber:
1. They continue to divide throughout childhood as skeletal muscles grow
2. Theyare formed by fusion of myoblasts during fetal development
3. They are true syncytium.
4. They are striated.
What happens during the contraction of a skeletal muscle fiber?
| 1. | The myosin filaments stay the same size but the actin filaments shorten |
| 2. | The sarcomeres shorten |
| 3. | The actin filaments stay the same size but the myosin filaments shorten |
| 4. | Both actin and myosin filaments shorten |
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In a skeletal muscle, ATP:
1. is required for the dissociation of myosin from actin
2. is hydrolyzed by the ATPase in actin myofilament
3. is used to replenish cretine phosphokinase
4. is not used in breaking of cross bridges
Identify the muscle protein that is/are regulatory in nature and are not directly involved in the act of contraction in a skeletal muscle:
1. Troponin and Calmodulin
2. Myosin
3. G Actin and F actin
4. Troponin and tropomyosin
Identify the correct statement regarding the excitation-contraction coupling with respect to skeletal muscle contraction:
1. It follows the formation of cross-bridges.
2. It Is the transmission of an impulse from the primary motor area to the anterior motor neuron in the spinal cord.
3. It causes reuptake of calcium by sarcoplasmic reticulum.
4. It describes what happens in a muscle fiber between stimulation by acetylcholine and cross-bridge formation.
Exposure to Sarin, a nerve gas will cause all the following except:
1. Failure to release acetylcholine at the neuromuscular junction
2. Prolonged depolarization of the motor end plate
3. Paralysis eventually leading to death
4. Inability to break down acetylcholine
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