neurones

• nosy neurone carry impulses from peripheral nervous system to central nervous system. They have long dendrites and short axons and they are located in the peripheral nervous system in clusters called ganglias. Their cell bodies are in the middle of the cell
• motor neurons connect the central nervous system to effectors such as muscles and glands. They have short dendrites and long axons. Their cell bodies may be in the central nervous system but their long axons form part of the peripheral nervous system
• relay neurones connect sensory neurones to motor or other relay neurones. They have short dendrites and short axons. 97% of all relay neurones are in the brain and visual system
• structures of neurones:

  • cell body- has a nucleus which contains genetic material
  • dendrites- branchlike structures which carry nerve impulses from other neurones towards cell body
  • axon- carries electrocal impulse away from the cell body. It is covered in myelin sheath that protects axon and nodes of Ranvier speed up impulse transmission
  • axon terminals- communicate with other neurones across the synapse
• when a neurone is in the resting state, the inside of the cell is negatively charged compared to the outside. When a neutron is activated, 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 neurone