external image moz-screenshot-6.jpgA neurone has a cell body with extensions leading off it. Numerous dendrons and dendrites provide a large surface area for connecting with other neurones, and carry nerve impulses towards the cell body. A single long axon carries the nerve impulse away from the cell body. The axon is only 10┬Ám in diameter but can be up to 4m in length in a large animal (a piece of spaghetti the same shape would be 400m long)! Most neurones have many companion cells called Schwann cells, which wrap their cell membrane around the axon many times in a spiral to form a thick insulating lipid layer called the myelin sheath. Nerve impulse can be passed from the axon of one neurone to the dendron of another at a synapse. A nerve is a discrete bundle of several thousand neurone axons.


Axons
Dendrites
  • Take information away from the cell body
  • Smooth Surface
  • Generally only 1 axon per cell
  • No ribosomes
  • Can have myelin
  • Branch further from the cell body
  • Bring information to the cell body
  • Rough Surface (dendritic spines)
  • Usually many dendrites per cell
  • Have ribosomes
  • No myelin insulation
  • Branch near the cell body
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http://www.biologymad.com/NervousSystem/nervoussystemintro.htm