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Acetylcholine: Definition, Function & Deficiency Symptoms

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  • 0:00 Definition Of Acetylcholine
  • 1:05 Functions Of Acetylcholine
  • 1:39 Acetylcholine Deficiency
  • 2:38 Lesson Summary
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Lesson Transcript
Instructor: Bethany Lieberman

Bethany is a certified OB/GYN nurse who has a master's degree in Nursing Education.

In this lesson, you will learn about acetylcholine, a chemical messenger that causes our skeletal muscles to contract and regulates our endocrine system. You'll find out how acetylcholine works and how a deficiency in this chemical can lead to serious medical conditions.

Definition of Acetylcholine?

Acetylcholine is a chemical that is found between the nerve synapses, or gaps, between nerve cells. When activated, it causes the contraction of skeletal muscles and activates glandular functions in the endocrine system. Think of acetylcholine as a mailperson; residents cannot receive their mail until he or she comes and delivers it to the mailbox. Like mailpersons who deliver the mail and move on to the next house, acetylcholine acts quickly and does not hang around. As a result, acetylcholine is rapidly broken down by another chemical substance called cholinesterase.

Acetylcholine was the first neurotransmitter scientists discovered, as well as the most abundant neurotransmitter in the body. A neurotransmitter is a chemical that is released by a neuron, or nerve cell, that sends a signal to another neuron across a synapse. The neurotransmitter binds to receptors to affect how the signal is received. The purpose of the neurotransmitter is to either amplify or inhibit the signals sent between the neurons.

Functions of Acetylcholine

Like mailpersons who can both deliver and pick up envelopes and packages, acetylcholine functions in the peripheral nervous system and central nervous system both as an activator and inhibitor. In the peripheral nervous system, it causes skeletal muscles to contract. In the central nervous system, it inhibits the activation of the cholinergic system.

Acetylcholine plays an important role in the signal of muscle movement, sensation of pain, learning and memory formation, the regulation of the endocrine system and rapid eye movement (REM) sleep cycles.

Acetylcholine Deficiency

Having too little acetylcholine can lead to medical complications. When we're deficient in this chemical, acetylcholine doesn't activate, and our nerves fail to receive their signals. Some conditions caused by acetylcholine deficiencies include myasthenia gravis, or 'grave muscle weakness,' according to the term's Greek and Latin origins.

Myasthenia gravis is an autoimmune disorder that typically affects the voluntary muscles of the eyes, face and mouth and neck. The muscles responsible for arm and leg movements may also be involved. Symptoms include difficulty in breathing, speaking and swallowing; double vision, droopy eyelids and muscle weakness.

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