structure and function of neurons

• structure and function of neurons

  • neurons carry neural info throughout the body
  • 3 types: sensory, relay and motor neurons
  • neurons consist of:
  • cell body
  • dendrites
  • axon
• dendrites

  • dendrites at one end receive signals from other neurons
  • are connected to cell body which is control centre + impulse is carried along axon (impulse now called action potential) + terminates at axon terminal
  • insulating layer around axon (myelin sheath) helps insulate to help signal travel more rapidly
  • length pf neuron can vary from a few mm's to a metre
• sensory neurons

  • carry nerve impulses from sensory receptors to spinal cord and brain
  • convert info from receptors in eyes, ears etc (other sensory organs) into neural impulses
  • in the brain they are translated into sensation eg, visual input
  • this allows the appropriate response to be intitiated
• relay neurons

  • most common neuron
  • allow sensory + motor neurons to communicate
  • also called interneurons
  • located in the brain + spinal cord (in the CNS)
• motor neurons

  • located in the CNS but project axons outside the CNS and control muscles
  • form synapses with muscles + control contractions
  • when stimulated, motor neurons release neurotransmitters that bind to receptors on the muscle + trigger a response which leads to muscle movement
  • strength of muscle contraction depends on rate of firing of axons + relaxation is result of inhibition of the motor neuron