neurones

• State the role of neurones

  Transmit electrical impulses rapidly so an organism can respond to changes in its internal and external environment
• Describe sensory neurones

  • Transmit impulses from sensory receptor cell to relay neurone, motor neurone, or brain
  • One dendron (carries impulses to the body) and one axon (carries them away from the body)
• Describe relay neurones

  • Transmit impulses between neurones (sensory and motor)
  • Short axons and dendrons
• Describe a motor neurone

  • Transmit impulses from a relay or sensory neurone to an effector (muscle or gland)
  • One long axon, many short dendrites
• Describe the structure of myelinated neurones and how they form that structure

  • Axon covered in myelin sheath
  • Made of many layers of plasma membrane
  • Schwann cells produce these layers of membrane by growing around the axon many times
  • myelin sheath acts as insulating layer so neurones conduct electrical impulse at faster speed than unmyelinated neurones
• describe the three key structures of a neurone

  • cell body- nucleus surrounded by the cytoplasm. Contain endoplasmic reticulum and mitochondria which produce neurotransmitters
  • dendrons- carry impulses to the cell body, divide into smaller branches known as dendrites
  • axon- transmit impulses away from the cell body. They can be very long
• describe what sensory, relay and motor neurones look like

  • dendrons
  • nuclei
  • cell body
  • myelin sheath
  • nodes of ranvier
  • dendrites
  • axon terminals
  • axon

  
• what is myelin sheath made up of?

  many layers of plasma membrane
• what produces myelin sheath?

  • schwann cells
  • they do it by growing around the axon many times
  • each time they grow around the axon, a double layer of phospholipid bilayer is laid down
• what is the role of myelin sheath in a neurone?

  acts as an insulating layer and allows myelinated neurones to conduct electrical impulses at a much faster speed than unmyelinated neurones