In order to stimulate muscle contraction, the axon terminal of the motor neuron
ID: 3514979 • Letter: I
Question
In order to stimulate muscle contraction, the axon terminal of the motor neuron must release ___(1)____. (a) actin (b) Ca^2+ (c) tropomyosin (d) acetylcholine
This densely packed bundle of protein fibers includes _____(2)______. (a) acetylcholine receptors (b) tropomyosin and troponin (c) Ca^2+ channel (d) myoglobin and hemoglobin
The membranes of these internal compartments contain _____(3)______. (a) voltage-gated Ca^2+ channels (b) actin and myosin (c) tropomyosin and troponin (d) acetylcholine receptors
Relaxed or Contracted on the left side
Relaxed or Contracted on the right side
Now, focus on a section of a single myofibril, isolated from the rest of the muscle fiber. This myofibril section is ---------- sarcomere(s) long. (a) more than three (b) about two (c) less than one
As a muscle fiber relaxes, the distance between the M lines and Z lines ____(1)____, and the width of the I-band ___(2)____.
(1) a. increases b, decreases c. stays the same
(2) a, stay the same b. decreases c. increases
The following diagram depicts the internal arrangement of cellular structures within a section of a single muscle fiber In order to stimulate muscle contraction, the axon terminal of the motor neuron must release acetylcholine . This densely packed bundle of protein fibers includes tropomyosin and troponin . The membranes of these internal compartments contain voltage-gated Ca2+ channels.Explanation / Answer
Now, focus on a section of a single myofibril, isolated from the rest of the muscle fiber. This myofibril section is --(b). About two-------- sarcomere(s) long. (a) more than three (b) about two (c) less than one.
Sarcomere is the distance between two z-discs.
As a muscle fiber relaxes, the distance between the M lines and Z lines ____(c)____, and the width of the I-band ___(c)____.
(1) a. increases b, decreases c. stays the same
(2) a, stay the same b. decreases c. increases
The distance between M lines and Z lines does not alter during muscle contraction and relaxation, and the width of I-band shortens during contraction and increases during relaxation.
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