Introduction and the Nervous System

• Neuron: The cells in the nervous system that carry information from one place to another by means of a combination of electrical and chemical signals.

           There are three types of neurons 

  1)       Sensory: brings information to the nervous system. This neuron is directly affected by changes in the environment such as light, odor, touch. 

  2)      Interneuron: associate information within the CNS. Receives input from and sends output to other neurons. 

  3)      Motor: sends information from the brain and spinal cord to the muscles. Transmits motor messages, stimulating a muscle or gland. 
• Motor neuron


  Sends information from the brain and spinal cord to the muscles. Transmits motor messages, stimulating a muscle or gland.
• Interneuron


  Associates information within the central nervous system (CNS). Receives input from and sends output to other neurons.
• Sensory neuron


  Brings information from the environment to the nervous system. Detects changes in the environment, such as light, odor, touch, or temperature, and transmits this information to the brain and spinal cord.
• Neuron


  A type of cell in the nervous system that transmits information from one place to another through electrical and chemical signals.
• Axon: A long fiber that carries nerve impulses away from the cell body. It can be very short or several feet long. Axons transmit information between neurons.
• Dendrite: Short fibers that extend outward from the cell body. They receive incoming nerve impulses.
• Glia


  • Supporting cells
  • Outnumber neurons
  • Critical to the functioning of the nervous system
• How glia support cells

  1. Modify the chemical environment between the communication of neurons

  2. Guide neurons as they migrate from the site of creation to their final position within the brain

  3. Remove dead neurons after brain damage

  4. Serve nutritive needs of neurons

  5. Provide structural support
• Glia's role in the blood-brain barrier

  • Packed glial cells between blood vessels and neurons
  • Prevents many harmful substances, such as toxins, from reaching the brain
• Glia is not directly responsible for transmission of information but they are needed for any transmission between neurons to be possible