Acetylcholine is one of the many neurotransmitters in the human body and the first researchers discovered. Neurotransmitters are special chemical substances that act as messengers for the human body. They transmit signals across chemical synapses from one neuron to another neuron, muscle cell, or gland cell. Acetylcholine has many important jobs, most notably supporting cognitive functions such as memory, alertness, and learning. Additionally, it helps skeletal muscles contract and has roles in the central and peripheral nervous system.


1. Peripheral Nervous System

In the peripheral nervous system, acetylcholine operates in the neuromuscular junction. It communicates between the motor nerve and skeletal muscles the body uses for voluntary movement. Motor neurons in the spinal cord or brain stem control the skeletal muscles by sending signals through motor nerves. These nerves connect to muscle fibers at the neuromuscular junction. When the neuromuscular junction receives these signals, the body initiates a process that releases acetylcholine. The acetylcholine then binds to nicotinic ion-channel receptors, causing ion channels to open. Sodium ions flow into the muscle cell, leading to a series of steps that produce muscle contraction and movement.

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