Neurons and synaptic transmission

• What is a sensory neuron?


  These carry messages from the peripheral nervous system to the central nervous system. They have long dendrites and short axons.

  
• What is a relay neuron?

  These connect the sensory neurons to the motor neurons or other relay neurons. They have short dendrites and short axons.

  
• What are motor neurons?

  These connect the central nervous system to effectors such as muscles and glands. They have short dendrites and long axons.

  
• What is the cell body?

  Includes a nucleus, which contains the genetic material of the cell.
• What are dendrites?

  Protrude from the cell body. These carry nerve impulses from neighbouring neurons towards the cell body.
• What are axons?

  Carries the impulses away from the cell body down the length of the neuron.
• What are myelin sheath?

  Protects the axon and speeds up electrical transmission of the impulse.
• What are nodes of Ranvier?


  These are gaps between myelin sheath. These speed up transmission of the impulse by forcing it to 'jump' across the gaps along the axon.
• The firing of a neuron:

  When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur. This creates an electrical impulse that travels down the axon towards the end of the neuron.