Myelin and the Central Nervous System

• What is the central nervous system?
• What is myelin?
• How is myelin destroyed?
• What happens when myelin is destroyed?
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What is the central nervous system?

The central nervous system is the part of the nervous system made up of the brain and spinal cord.

The central nervous system

• The brain controls most bodily functions, such as voluntary movements, perception of sensations, memory, awareness, and thoughts.  
  
  
  • The cerebrum controls voluntary actions, speech, thought, and memory. The cortex, also called gray matter, is the outer part of the cerebrum and is made of neurons (nerve cells). Most of the brain's information processing is done in the cortex. 
  
  
  
  • The brain is divided into 2 halves: the right hemisphere and the left hemisphere. These hemispheres lie on a central structure called the thalamus, which relays information between the peripheral input from the senses and the brain. Other central structures include the hypothalamus, which regulates automatic functions such as appetite and thirst, and the pituitary gland, which is partially responsible for growth, metabolism, and stress response.
  
  
  
  • The brain is connected with the brainstem (midbrain, pons, and medulla). The cerebellum is located posteriorly to the brainstem and plays a role in maintaining equilibrium and muscle tone. It also participates in complex mathematical and musical skills.
    
    
• The spinal cord sends messages from the brain to different parts of the body and receives messages back. The spinal cord is surrounded by the spinal column, which is made up of stacked bones called vertebrae.



• See Anatomy of the Central Nervous System for more information.