The Nervous System is like a computer for your body. It gets information from all parts of the body. It also gets information from the environment. It examines the information. Then it tells the body what to do. The nervous system does its job by carrying messages between the brain and spinal cord, and other parts of the body. The messages it carries are like tiny electric sparks.

Neurons

        The basic part of the Nervous System is a cell called a neuron. Messages move from neuron to neuron along threadlike branches. The neurons are arranged in bundles called nerves. They are the longest cells in the human body.

Sensory and Motor Nerves

        Two main kinds of nerves are sensory nerves and motor nerves. Sensory nerves bring messages from the sense organs to the brain or the spinal cord. Your eyes, ears, nose, mouth, and skin are sense organs.

        Motor nerves carry messages from the brain and the spinal cord to other parts of the body. When you hear a friend say hello, sensory nerves carry the sound from your ears to your brain. Your brain understands the sound. It decides that you should wave.

        The brain sends a message to the spinal cord. The spinal cord sends the message to motor nerves of your arm. These nerves cause the muscles of your arm to move. This action is voluntary. It is something you do on purpose. It happens because of a decision made by your brain.

        The main control center of the body is the brain. Together, the brain and the spinal cord direct all the actions of the body. The brain and the spinal cord make up the Central Nervous System.

Reflexes

        Some of your actions use your spinal cord, but not your brain. Suppose you touch a hot pan. Sensory nerves in your skin send a message about heat to the spinal cord. The spinal cord sends the message to motor nerves. These nerves cause the muscles of your arm to move. The muscles pull your hand away from the pan before you get burned.

        This action is a reflex. You do not have to use your brain to think about it. It is involuntary. Other reflexes are blinking, sneezing, and coughing. Look at the drawing of the brain. Then look at the table. Learn which parts of your brain control different actions.