Question

the sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called:
a myofilaments
b cell body of neuron
c neuromuscular junctions
d sarcomeres
e z disks

Explanation:

• Myofilaments: These are the contractile proteins (actin and myosin) within muscle fibers, not related to neurotransmitter transmission.
• Cell body of neuron: It is the part of the neuron that contains the nucleus and organelles, not the site of neurotransmitter release to muscle fibers.
• Neuromuscular junctions: This is the specialized synapse where a motor neuron (axon terminal) communicates with a muscle fiber (postsynaptic membrane) via neurotransmitters (like acetylcholine).
• Sarcomeres: The basic unit of muscle contraction (composed of myofilaments), not the site of neurotransmitter transmission.
• Z - disks: Part of the sarcomere that anchors actin filaments, not involved in neurotransmitter transfer from neuron to muscle.

Answer:

C. neuromuscular junctions