Neuron

• The neuron is a nerve cell that transfers information between the nervous systems. There are billions within the human body. A nerve cell sends electrical messages around the brain and the body. It is thought that we have 100 billion + nerve cells in the CNS and the majority of these are in the brain.
• Structure:

  The cell body includes a nucleus which contains the genetic material of the cell.

  Branch like structures called dendrites protrude from the cell body carry nerve impulses from neurons towards cell body.

  Axon carries impulse away from cell body down the length of the neuron. Axon covered in a fatty layer of myelin sheath that protects the axon and speeds up the electrical transmission.
• Structure:

  Gaps along axon called: nodes of Ranvier which speed up the transmission along the axon as the impulses jump across the gaps along the axon.

  End of the axon are terminal buttons that communicate with the next neuron- synapse
• Structure:

  
• Sensory neurons

  • carries messages from PNS to CNS
  • processes information taken from one of the senses
  • LONG dendrites
  • SHORT axons
• Relay neurons

  • connect sensory neurons to motor or other relay neurons
  • SHORT dendrites
  • SHORT axons
• Motor neuron

  • connects CNS to effectors such as muscles and glands
  • SHORT dendrites
  • LONG axons