function and structure of neurons

• sensory neuron


  carries messages from PNS to CNS
• relay neuron


  connects sensory neurons to motor neurons
• motor neuron 


  connects the CNS to effectors (muscles and glands)
• axon


  carries electrical impulses away from cell body
• cell body


  include nucleus - contains genetic material
• dendrites


  branch like structures that carry electrical impulses towards cell body
• myelin sheath


  fatty layer around axon that protects it and speeds up electrical transmission
• nodes of ranvier 


  gaps in myelin sheath that speed up electrical impulses by jumping across gaps along axins
• terminal buttons

  end of axon. also communicates with next neuron in chain (synapse) across a gap