Acetylcholine, what it is and what functions it has

Acetylcholine, what it is and what functions it has

Acetylcholine is a neurotransmitter, a chemical released by nerve cells to send signals to other cells. Its name derives from its molecular structure: it is an ester of acetic acid and choline (ACh). It was the first neurotransmitter to be discovered, and for this reason it has been very studied. It is also the most abundant neurotransmitter and It is present in both the central nervous system (CNS) and the peripheral nervous system (SNP).

Acetylcholine is the main neurotransmitter of autonomic nervous system, which has such important functions as contracting smooth muscles, dilating blood vessels, increasing body secretions and decreasing heart rate.


  • 1 What does Acetylcholine do?
  • 2 How acetylcholine works
  • 3 Acetylcholine and its relationship with Alzheimer's and Parkinson's

What does acetylcholine do?

Acetylcholine fulfills both excitatory and inhibitory functions, which means that it can accelerate and slow nerve signals.

Role of acetylcholine in the CNS

In the Central Nervous System, its function is mainly excitatory. It is responsible for modulating the functioning of various neurons in areas of the brain that control motivation, excitement and attention. It is a key neurotransmitter to maintain the memory and encourage learning, in addition to promoting neuroplasticity cerebral. Critical deterioration of the cholinergic pathway in the CNS has been associated with the onset of Alzheimer's disease.

It also helps activate sensory functions upon awakening, helping people maintain attention and acting as part of the brain's reward system. Acetylcholine It is essential for sleep with rapid eye movement (REM), when people have our dreams when we are sleeping.

In the brain, acetylcholine acts as a neuromodulator, which means that instead of participating in direct synaptic transmission between specific neurons, they act in a wide variety of neurons throughout the nervous system. Drugs and substances that disrupt the function of acetylcholine can have negative effects on the body and even cause death. Examples of such substances are some types of pesticides and neurotoxic gases.

Role of acetylcholine in the SNP

Inside of the peripheral nervous system, acetylcholine is an important part of autonomic nervous system, since it transmits the signals between the motor nerves and the muscles, contributing to the contraction of cardiac, skeletal and smooth muscles. It acts on the neuromuscular junctions allowing motor neurons to activate muscle action.

For example, the brain could send a signal to move the left leg. The signal is transported through the nerve fibers to the neuromuscular junctions. Once there, the signal is transmitted by acetylcholine, triggering the desired response in those specific muscles.

Acetylcholine is responsible for controlling numerous bodily functions, as it acts on the preganglionic neurons of the sympathetic and parasympathetic systems.

In the Cardiovascular system, acts as a vasodilator, decreasing heart rate and heart muscle contraction. In the gastrointestinal systemIt acts by increasing peristalsis in the stomach and the extent of digestive contractions. In the Urinary tract, its activity is focused on decreasing bladder capacity and increasing the voluntary feeling of evacuation. It also affects the respiratory system stimulating the secretion of all glands that receive parasympathetic nerve impulses. In the central nervous system, acetylcholine appears to have multiple functions.

Because acetylcholine plays an important role in all muscle actions, drugs that influence this neurotransmitter can cause various degrees of movement disruption or even paralysis.

Imbalances in acetylcholine may contribute to the development of myasthenia gravis, an autoimmune disorder that causes muscle weakness and fatigue.

How acetylcholine works

In the SNP, acetylcholine is stored in the vesicles found at the ends of cholinergic neurons (producing acetylcholine). In the SNP, when a nerve impulse reaches the terminal of a motor neuron, acetylcholine is released at the neuromuscular junction. There it is combined with a receptor molecule in the postsynaptic membrane (or membrane of the end plate) of a muscle fiber. This junction changes the permeability of the membrane, which causes channels are opened that allow positively charged sodium ions to flow into the muscle cell. If the successive nerve impulses accumulate at a sufficiently high frequency, the sodium channels along the membrane of the end plate become fully activated, which results in the muscle cell contraction.

Acetylcholine it is quickly destroyed by the enzyme acetylcholinesterase and therefore is only briefly effective. Enzyme inhibitors (medicines known as anticholinesterases) prolong the life of acetylcholine. Such agents include physostigmine and neostigmine, which are used to help increase muscle contraction in certain gastrointestinal conditions and in myasthenia gravis. Other acetylcholinesterase have been used in the treatment of Alzheimer's disease.

Acetylcholine and its relationship with Alzheimer's and Parkinson's

The cholinergic portion of the brain is the area of ​​the brain that produces acetylcholine. The damage to this part of the brain is related to the development of the Alzheimer disease. Many people with Alzheimer's disease have altered levels of acetylcholine. Cholinesterase inhibitors are usually prescribed to people with Alzheimer's disease in an effort to slow the development of this condition by preventing the breakdown of acetylcholine.

Acetylcholine also plays an important role in the Parkinson's disease. Acetylcholine along with the dopamine They are the neurotransmitters that allow smooth muscle movements. When there is an imbalance between acetylcholine and dopamine, movements can be unstable and uneven, a hallmark of Parkinson's disease.

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American Psychological Association. APA Concise Dictionary of Psychology. Washington, DC