Human Body Systems Human Body Systems Lesson 15 – Your Nervous System

Your Nervous System

Vocabulary

Read the vocabulary terms to understand the reading better.

Brain

The brain is the complex organ that controls all of the body’s senses, movements, and functions; the brain, spinal cord, and nerves make up the body’s nervous system.

Nerve Cells

Nerve cells are a small part of the nervous system along which signals are sent and received; also called neurons.

Nervous System

The nervous system is a body system made up of the brain, spinal cord, and nerves that control the body’s reactions to things it feels, smells, tastes, hears, and sees.

Neurons

Neurons are nerve cells that send and receive signals in the body.

Reflex

A reflex is an automatic response or reaction that occurs due to a specific cause, such as jumping when a sudden, loud sound occurs.

Spinal Cord

The spinal cord is the thick, whitish cord of nerve tissue that extends from the brain stem down through the spine and branches off into nerves that extend throughout the body.

Feeling, seeing, hearing, moving, thinking. You can do all of these things at the same time, thanks to your nervous system. It is the control centre of your body. It automatically regulates many of your body’s processes.

The Brains Behind the Operation

The central nervous system is made up of your brain and spinal cord. They are linked to your body through a network of nerve cells.

Nerves use electricity and chemicals to transmit messages. These messages go to and from your brain.

Making Sense

You have five senses: sight, hearing, smell, taste, and touch. Your eyes, ears, nose, mouth, and skin all send messages to your brain. The brain processes the messages and allows you to sense and react to your environment.

A Matter of Survival

Your nervous system is important for your survival. For example, if you touch something hot, you quickly move your hand away.

That reaction is automatic—a reflex. If you see a car racing toward you, your eyes send a message to your brain. Your brain delivers a message to your feet to start running.

*a reflex is an automatic reaction to something*

Your Amazing Nervous System

There are thousands of kilometres of nerves in your body. Laid out end to end, your nerves would wrap around Earth twice! Nerves carry messages at the speed of 430 km/h.

There are nerve cells called neurons that run from your spinal cord to your toes. Neurons are the longest cells in your body. They are incredibly narrow, but are up to 1.2 m long.

Feed Your Brain

You sleep and do not eat during the night. Your brain needs fuel when you wake up. Experts have shown that “hungry” brains have trouble remembering things. They also have trouble learning new information. So do your brain a favour—eat breakfast! Protein foods are very good “brain foods” for breakfast. Protein foods include eggs and nuts. Oatmeal cereal and whole-grain bread are also good breakfast foods.