Cell body

· Contains nucleus and large amounts of Rough Endoplasmic Reticulum

· Associated with production of proteins + neurotransmitters


· Small extensions of the cell body

· Subdivide into smaller branched fibres (dendrites)

· Carry nerve impulses towards the cell body


· Single long fibre

· Carries nerve impulses away from cell body

Schwann Cells

· Surrounds axon

· Wraps around axon many times to form layers of membrane

· Protects axon and provides electrical insulation

· Carries out phagocytosis

· Used in nerve regeneration

Myelin Sheath

· Forms a covering to the axon

· Made up of the membranes of the Schwann cells

· Rich in lipids (myelin)

· Myelinated neurons are those that contain a myelin sheath

· Transmit nerve impulses faster (relative to unmyelinated)

Node of Ranvier

· Gaps between adjacent Schwann cells (where there is no myelin sheath)

· Gaps are 2-3μm long and occur every 1-3mm (humans)


Types of Neuron

  • Sensory Neurone:
    • Transmits nerve impulses from a receptor to an intermediate/motor neuron
    • Have one dendron which carries the impulse towards the cell body
    • One axon that carries it away from the cell body
  • Motor Neurone:
    • Transmit nerve impulses from an intermediate/sensory neuron to an effector
    • Have a long axon and many short dendrites
  • Intermediate Neurone:
    • Transmits impulses between neurones
    • Numerous short processes