Neurons and nerve impulses

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  • Created by: sierrah
  • Created on: 11-04-14 01:49
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  • Nerve cells and impulses
    • Two parts
      • Central nervous system (CNS)
        • Brain and spinal cord
      • Peripheral nervous system (PNS)
        • Nerves that connect the CNS with muscles, glands and reactors
    • Neuron (nerve cell)
      • Basic  structural/functional unit of the nervous system
      • Vary in shape and size
      • Consist of cell body and two extensions: axons and dendrites
    • Structure
      • Axon
        • Often single long extension, carries nerve impulses away from cell body - EFFERENT PROCESS
      • Dendrite
        • Usually fairly short extension
        • Carries nerve impulses towards cell body
      • Schwann cell
        • Produces myelin sheath, involved in repair of fibres
      • Neurilemma
        • Outer membrane of Schwann cell, maintains and regenerates fibres
      • Myelin sheath
        • Layer of fatty material
        • Acts as insulator, assists with fibre repair, and speeds up nervous transmission
      • Nodes of Ranvier
        • Gaps in myelin sheath, speed up nervous transmission
      • Synapse
        • Junction between neurons, slowest part of transmission
      • Cell body
        • Mass of neuroplasm surrounding nucleus, directs activities of the rest of the cell
    • Types of neurons
      • Sensory
        • Conduct impulses from sensory organs/receptors to the CNS
      • Motor
        • Carry impulses from the CNS to effectors i.e. muscles/glands
      • Connector/association
        • Located in CNS
        • Connect sensory/motor neurons
  • Carries nerve impulses towards cell body

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