The somatic motor neuron
A)causes release of ACh into the NMJ.
B)stimulates the SR to release calcium into the sarcomeres.
C)moves the tropomyosin away from the myosin binding sites on actin.
D)stimulates the axon terminal to release calcium into the NMJ.

Question

Quizplus · Accepted Answer

The somatic motor neuron causes release of ACh (acetylcholine) into the neuromuscular junction (NMJ), which binds to the receptors on the sarcolemma (muscle fiber membrane) and triggers an action potential.

Answer: B
 The stimulation of the sarcoplasmic reticulum (SR) to release calcium into the sarcomeres is performed by the action potential, but it is not directly caused by the somatic motor neuron.

Answer: C
 The movement of tropomyosin away from the myosin binding sites on actin is triggered by the binding of calcium to troponin, which is itself triggered by the influx of calcium into the sarcomeres, but it is not directly caused by the somatic motor neuron.

Answer: D
 The stimulation of the axon terminal to release calcium into the NMJ is not a physiological process that occurs in skeletal muscles. The axon terminal releases acetylcholine, not calcium.

The Somatic Motor Neuron