Nerve cells

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  • Created by: Laura
  • Created on: 14-04-14 16:09
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  • Nerve cells
    • The nervous system is composed of nerve cells or neurones. A neurone has a cell body with extensions leading off it.
    • Several dendrons carry nerve impulses towards the cell body while a single long akon carries the nerve impulse away from the cell body.
    • Nerve impulses are passed from the axon of one neurone to the dendron of another at a synapse. Numerous dendrites provide a large surface area for connecting with other neurones.
    • Most neurones also have many companion cells called shwann cells which are wrapped around the axon many times in a spiral to form a thick lipid layer called the myelin sheath.
      • This provides physical protection and electrical insulation for the axon. There are gaps in the sheath called Nodes of Ranvier
    • Sensory neurone -they have long dendrons and transmit nerve impulses from sensory receptors to the central nervous system.
    • Effector/ motor neurone - they have long axons and transmit nerve impulses from the central nervous system to effectors all over the body
    • Interneurones /relay neurones - these are much smaller with many connections. They comprise the central nervous system, 99.9% of all neurones are relay neurones.

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