Question

The somatic nervous system can alter the activities of its targets, the skeletal muscle fibers, because?

A. its light pulses activate contraction in the muscles.
B. it is electrically coupled by gap junctions to the muscles.
C. its signals reach the muscles via the blood.
D. it is connected to the internal neural network of the muscles.
E. its signals bind to receptor proteins on the muscles."

Answer 1

The somatic nervous system influences skeletal muscle fibers through signals that bind to receptor proteins at the neuromuscular junction, triggering muscle contraction.

Step-by-step explanation:

The somatic nervous system can alter the activities of its targets, the skeletal muscle fibers, because its signals bind to receptor proteins on the muscles. This occurs at a specialized synaptic structure known as the neuromuscular junction, where motor neuron axons connect to muscle fibers. Motor neurons secrete the neurotransmitter acetylcholine (ACh), which then binds to receptors on the muscle fiber sarcolemma. This binding of ACh opens ligand-gated ion channels, allowing cations to flow across the sarcolemma, subsequently depolarizing it and initiating muscle contraction. The entire process, from signal initiation in the nervous system to muscle contraction, is what enables voluntary movements and is essential for bodily functions.