Health Library

What Is the Nervous System?

The nervous system includes the brain, spinal cord, and a complex network of nerves. This system sends messages back and forth between the brain and the body.

The brain is what controls all the body’s functions. The spinal cord runs from the brain down through the back. It contains threadlike nerves that branch out to every organ and body part. This network of nerves relays messages back and forth from the brain to different parts of the body.

What Are the Parts of the Nervous System?

The nervous system is made up of the central nervous system and the peripheral nervous system:

• The central nervous system includes the brain and spinal cord.
• The peripheral nervous system includes the nerves that run throughout the whole body.

How Does the Nervous System Work?

The nervous system uses tiny cells called neurons (NEW-ronz) to send messages back and forth from the brain, through the spinal cord, to the nerves throughout the body.

Billions of neurons work together to create a communication network. Different neurons have different jobs. For example, sensory neurons send information from the eyes, ears, nose, tongue, and skin to the brain. Motor neurons carry messages away from the brain to the rest of the body to allow muscles to move. These connections make up the way we think, learn, move, and feel. They control how our bodies work — regulating breathing, digestion, and the beating of our hearts.