Acetylcholine: Definition, Function & Deficiency Symptoms

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Catecholamines: Definition & Function

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:00 Definition Of Acetylcholine
  • 1:05 Functions Of Acetylcholine
  • 1:39 Acetylcholine Deficiency
  • 2:38 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

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.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account