MUSCLE PHYSIOLOGY

Detailed explanation-1: -The release of acetylcholine occurs when an action potential is relayed and reaches the axon terminus in which depolarization causes voltage-gated calcium channels to open and conduct an influx of calcium, which will allow the vesicles containing acetylcholine for release into the synaptic cleft.

Detailed explanation-2: -Once the action potential reaches the end of the axon terminal, it causes the neurotransmitter acetylcholine (ACh) from synaptic vesicles in the axon terminal. The ACh molecules diffuse across the synaptic cleft and bind to the muscle fiber receptors, thereby initiating a muscle contraction.

Detailed explanation-3: -Acetylcholine is the primary neurotransmitter of the parasympathetic nervous system. Acetylcholine is released from synaptic vesicles (from the pre-synaptic neuron) by the process of exocytosis. This process involves the extracellular transport of materials from a cell. Therefore, the answer is d) exocytosis.

Detailed explanation-4: -When acetylcholine is released from the axon terminals, it binds to specific proteins called acetylcholine receptors3 on neighboring neurons or on other types of cells, like muscle cells.