What is a Nerve? - Definition & Associated Terminology

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  • 0:01 Neurons & Receptors
  • 0:36 What are Nerves?
  • 2:04 Nerve Tracts & Structures
  • 3:13 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson defines and explains what nerves are as well as associated terminology: neurons, receptors, impulse, stimulus, ascending and descending nerve tracts, ganglion, and plexus.

Neurons & Receptors

You are getting on my nerves! I've heard that once or twice before from people. We all know what that expression means, but what are nerves, truly?

First, I'll tell you what they're not. They are not neurons, nerve cells. They have to do with neurons, however. Nerves are not receptors either. Receptors are oftentimes protein molecules on or within a cell that bind, recognize, and respond to specific molecules.

So what are nerves, then? Let's find out.

What Are Nerves?

You're viewing this lesson on some sort of screen right now. I'm willing to bet that screen or the projector for that screen has at least one wire coming off of it. If you were to very carefully and safely pull that wire apart, you'd notice it's actually made up of several different fibers that send electrical signals.

That wire is like a nerve as a result because a nerve is a cordlike collection of nerve fibers that send electrochemical signals between different parts of the body. The combining form of neur/i or neur/o refers to a nerve, by the way.

Those nerve fibers are the axons of neurons. Axons carry signals away from a nerve cell's body when they are stimulated to do so. A stimulus is anything that activates a nerve cell or nerve and causes an electrochemical signal, called an impulse, to be propagated along a nerve fiber.

Like a wire has many fibers that carry signals away from many different parts of the screen or projector, a nerve has nerve fibers, which carry signals away from many different neurons. Knowing this, the definition of innervation should be easy, as it simply means the supply of nerves to an organ or body part.

Nerve Tracts & Structures

Nerves that supply any body part can send impulses (or signals) to and from the brain. Ascending nerve tracts conduct nerve impulses to the brain while descending nerve tracts conduct nerve impulses away from the brain.

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