Catheterisation

The nervous system acts as the body's internet.  It is where feelings, memories and information are continuously circulated throughout the body to make us act in different ways.

The nervous system is made up of three parts: 

• The Brain 
• The Spinal Cord 
• The Nerves

The Brain

The brain is the central computer; the body's hard drive.  It receives information from the nerves which it either saves or uses to instruct the body to do something.

The Spinal Cord

The spinal cord is a cable about 1cm in diameter that runs from the brain through the canal that the holes in the middle of the vertebrae form.  

From the spinal cord, nerves spread out to all parts of the body.  However, the nerves that go to the eyes, the ears and other parts of the head go directly from the brain, not via the spinal cord.

The Nerves

There are two kinds of nerves. One kind carries information to the spinal cord and the brain. The other kind carries orders from the brain and the spinal cord. 

Imagine you're at the beach.  A message from your toes to your brain could sound like this: 'The water is cold'.  The message from your toes is sent by a nerve to the spinal cord and then it is passed up to the brain. The brain gives an order: 'Pull the toes out of the water!'  This order is passed through the spinal cord and along a nerve to the leg muscle that can pull your toes out of the water. 

Sometimes you need to act fast.  If you touch a very hot cooking pot, the message only goes to the spinal cord which then immediately gives your arm muscle an instruction to pull your hand away from the cooking pot. This is called a reflex action. If this message had been forced to go all the way to the brain and the order, to release the pot, had been forced to make the entire journey back, you might have burned yourself. 

Other reflex actions are blinking and sneezing.