In the peripheral nervous system, what is the main role of acetylcholine?

Acetylcholine plays a crucial role in muscle contraction within the peripheral nervous system. When a nerve impulse reaches a neuromuscular junction, acetylcholine is released from the motor neuron into the synaptic cleft. This neurotransmitter then binds to receptors on the muscle cell membrane, leading to depolarization of the muscle fiber and initiating a series of events that ultimately result in muscle contraction. This process is vital for all voluntary movements and many involuntary responses.

While acetylcholine also has roles in other systems, such as contributing to various brain functions like memory (notably in the central nervous system), its primary and most well-studied function in the peripheral nervous system pertains to muscle contraction.