The Nervous System

Our nervous system could be compared to a network of electrical wiring. It is what sends signals to the body to coordinate any and all of the actions and without it we couldn’t move.

The nervous system is made up of a lot of parts including glial cells, neurons, and axons.

The nervous systems in those animals that have spinal columns or backbones (vertebrates) is made up of two parts: the CNS or central nervous system and the PNS or peripheral nervous system.

The CNS includes the retina of the eyes, the spinal cord, and the brain. The brain is covered in a protective shell of the skull and the spinal cord is protected by the skeletal vertebrae.

The PNS includes all of the other structures of the nervous system that actually sit outside of the CNS but that helps to connect the CNS to various other parts of the body.

Long fiber bundles called axons enclose the nerves and the axons are each made up of nerve cells.

There are two specific types of nerve cells: Glial cells and neurons.

Glial is also known as ‘glia’ and the word actually comes from the Greek word that means ‘glue’. These are very specialized cells that provide support and structure to the neurons. They also hold them in place, supply nutrients, remove dead neurons, and destroy germs as well as direct the axons of the neurons.


There are some types of glial cells that work as a kind of electrical insulation. They create myelin, which is a substance that coats axons so that it helps the fast and efficient transmission of signals.

  • The job of neurons is the send electrochemical waves as signals in a precise and fast manner to along the axons to other cells.
  • There are two types of neurons: Motor neurons and sensory neurons.
  • Sensory neurons have the sole responsibility to change touch, light and sound into neural signals that are sent back to the CNS so that our bodies can understand and even react to our surroundings.

Motor neurons are the ones that send neural signals so that our muscles or glands are activated.

  • The human brain has approximately 100 billion neurons.
  • The human spinal cord has about 13.5 million neurons.
  • The nervous system is incredibly fast. It can send signals throughout the body as 328 feet per second (100 meters).
  • Neuroscience is the field of study for the nervous system. The medical branch of treatment and study within neuroscience is called neurology.




The nerves in our bodies are vulnerable to damage from both disease and physical sources. Nerve damage can cause intense pain, loss of muscle control, or even loss of feeling.

Some nerve damage can be unpredictable. It can seem like it is ok one minute and then cause a problem next. Surgeons that perform surgery on the nervous system are called neurosurgeons.

When patients experience nervous system damage they go-to specialists for treatment. These are call Physiatrists.

The brain is the main controller for the nervous system. When you touch something that is too hot, the sensation is sent to the brain and the brain then tells the arm, hand, and muscles to remove your hand.

Part of the brain that controls your concept of thirst as well as your body temperature and other functions is called the ‘hypothalamus’. When you get cold, the brain sends a message to your body to shiver, which in turn makes your muscles vibrate to generate heat.