Neurones

• Neurones


  • Very specialised cells
  • Very long
  • Have branched ends that can make connections with many other (nerve) cells
  • Surrounded by an insulating myelin sheath
• Nucleus


  Direction of nerve impulse
• Many branched endings


  Form junctions with other nerve cells
• Ends


  Link with adjacent nerve cells
• Axon


  • Part of the neurone that gives it its long length
  • Insulating myelin sheath both insulates neurones and enables them to conduct impulses faster
• Figure 6.4 represents a motor neurone, with the cell body at the start of the axon
• Figure 6.2 shows that the cell body is on a side branch in sensory neurones
• Types of neurones


  • Sensory neuron
  • Association neuron (relay)
  • Motor neuron
• Nerve cells are called neurones
• Neurones


  Link receptors (e.g. eye, ear...) and effectors (muscles) to the coordinators (brain & spinal cord)
• Neurones


  • Specially adapted to carry electrical messages called nerve impulses
  • Have branched ends (dendrites) that allow them to transmit impulses over a greater area or to make more connections with other neurones
  • Axon is long to transmit information between different areas of the body (can be up to 1m)
  • Coated with an insulating sheath that helps speed up the transmission of an impulse by acting as an insulator
  • Nucleus of the cell is found in the cell body surrounded by cytoplasm
• A Neurone

  
• When a stimulus reaches a sensory neurone it causes a change in its membrane potential. This can cause a nerve impulse to travel along the axon towards the brain/spinal cord.
• a MOTOR Neurone