Neurone structure

• Label this diagram of a motor neurone

  A) nucleus

  B) dendrite

  C) cell body

  D) myelin sheath

  E) node of Ranvier

  F) Schwann cell

  G) axon terminal

  H) axon

  I) dendron

  
• What is a dendrite?

  Extensions of the cytoplasm where an impulse is received
• What is the axon?


  A long extension that carries impulses away from the cell body. It is filled with cytoplasm (axoplasm)
• What are Schwann cells?

  -cells that wrap around the axon

  -they secrete myelin (a lipid)

  -this forms the myelin sheath along the axon gaps (nodes of Ranvier)
• What is myelin and what does it do?

  -an electrical insulator

  -where myelin is present, ions (Na+ and K+) are not able to move across the axon membrane in or out of the axon

  -ions can only do this at nodes of Ranvier

  -so an impulse jumps from one node to the next, which speeds up conduction
• What is an axon terminal?

  -end of neurone

  -where neurone synapses with an effector