Nervous System

Say you are on a walk. You are coming to a place where you need to cross the street. You look both ways, no body is coming. But then, as soon as you start to walk a car comes your way going really fast. The next thing you know your running back to the side of the street to get out of it's way. Your heart is pounding and you're breathing really hard and fast.


When you saw the car coming, the sensory receptors in your eyes were stimulated. A message was then sent to your brain by sensory neurons. Impulses reach your brain or spinal cord, and interneurons relay the impulses from the sensory to the motor neurons. Your brain sorted the information and determined the response it would take. The response was sent back along motor neurons to your muscles. Your heart then immediately started to pound and your breathing rate increased.


The working part of the Nervous System is the nerve cell, also known as a neuron. It is made up of a cell body and branches called dendrites and axons. 

Nerves (green)

Dendrites receive massages and send them to the cell body.


Axons carry messages away from the cell body.


Any message carried by a neuron is called an impulse.

The central nervous system (or CNS) is made up of the brain and spinal cord while the peripheral nervous system (or PNS) is made up of all the nerves outside of the CNS, including cranial and spinal nerves. These nerves connect the brain and spinal cord to the other body parts.

Central Nervous System

Because of having a central nervous system with a brain, your body activities are coordinated. For example, if someone hits you in the ribs, your whole body will react.




Your brain (the organ that controls your whole entire body) is made up of approximately 100 BILLION neurons. Your brain is divided into three major parts, the cerebrum (where the impulses from the senses are interpreted, your memory is stored, and voluntary muscles are controlled), the cerebellum (where the voluntary muscle movements are coordinated and balance and muscle tone are maintained), and the brain stem (which extends from the cerebrum and connects the brain to the spinal cord. It controls your heartbeat, breathing and blood pressure). 

Your spinal cord is an extension of the brain stem. It's made up of bundles of neurons that carry impulses from all parts of your body to your brain and from your brain to all parts of your body. Your spinal cord is about as big around as an adult thumb and 43 centimeters long.

A reflex (part of the PNS) is an involuntary and automatic response to a stimulus. Usually you can't control your reflexes because they happen before you know what's going on.

Be sure not to do drugs, drink alcohol or have to much caffeine to be sure your Nervous System stays in check.

Pictures found at

http://6keysoptimalhealth.blogspot.com/2009/11/pain-relief-and-chiropractic-wellness.html  (picture on top)

http://drugster.info/ail/pathography/2734/  (central nervous system)

http://morphonix.com/software/education/science/brain/game/specimens/wet_brain.html  (brain)

http://www.typefreediabetes.com/Articles.asp?ID=219  (peripheral nervous system)

http://cdrlibraryblog.blogspot.com/2010_08_01_archive.html  (spinal cord)

http://science.howstuffworks.com/environmental/life/human-biology/nerve.htm  (nerves)

http://morphonix.com/software/education/science/brain/game/specimens/neuron_parts.html  (neuron)