structure and functions of neurons

• Neurons

  communicates by transmitting electrical and chemical signals and part of the nervous system
• sensory neurons

  • receptor cells
  • Myelin sheath
  • Axon
  • Cell body
• sensory neurons

  • carry messages from the PNS to the CNS
  • found in receptors such as eyes, ears, tongue
  • carry nerve impulses to the spinal cord and brain
  • however, some sensory neurons stop at the spinal cord, allowing for quick reflex actions
• Relay neurons

  • dentrite
  • cell body
  • axon
  • presynaptic terminal
• Relay neurons

  • found between sensory input and motor output
  • found in the brain/ spinal cord allowing sensory and motor neurons to communicate
• Motor neurons

  • dendrite
  • cell body
  • myelin sheath
  • axon
  • node of ranvier
• motor neurons


  • connect the CNS to effectors (muscle/glands)
  • found in CNS and controls muscle movement.
  • when stimulated they release neurotransmitters that bind to the receptors on muscles and trigger a response which leads to movement.
• cell body


  includes a nucleus which contains the genetic material of the cell
• Dendrites


  carry nerve impulses from neighbouring neurons to the cell body.
• Axons


  carry impulses away from the cell body down the length of the neuron
• Myelin sheath


  • fatty layer covering the axon
  • protects the axon and speeds up electrical transmission of the impulse
• Nodes of Ranvier


  • The gaps in myelin sheath
  • speeds up transmission of impulse by forcing it to jump across the gaps in the axon.
• Terminal buttons


  communicate with the next neuron in the chain across a gap known as the synapse