Acetýlkólín

Acetylcholine, often abbreviated as ACh, is a neurotransmitter, a chemical substance that transmits signals across a synapse between two neurons, or between a neuron and a muscle or gland cell. It is the first neurotransmitter to be discovered, identified in the 1920s. Acetylcholine plays a critical role in both the central nervous system and the peripheral nervous system.

In the peripheral nervous system, acetylcholine is the primary neurotransmitter at the neuromuscular junction, the site where a motor neuron communicates with a muscle fiber. This action is essential for muscle contraction. It is also a key neurotransmitter in the autonomic nervous system, mediating functions of the parasympathetic nervous system, which is involved in rest and digest activities.

Within the central nervous system, acetylcholine is involved in a variety of functions including attention, learning, memory, and arousal. Deficiencies in acetylcholine signaling are associated with neurodegenerative diseases such as Alzheimer's disease, where it is believed to contribute to cognitive decline. Conversely, excessive acetylcholine can lead to muscle spasms and other symptoms. Acetylcholine is broken down by enzymes called acetylcholinesterases, which rapidly terminate its signal to prevent continuous stimulation.