Chapter 2 - Nerves

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  • Created by: stef17
  • Created on: 20-04-16 10:35
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  • Chapter 2 - Nerves
    • Types of Neurones
      • Intermediate (Relay) Neurones
        • Carry impulses from and to numerous other neurones
      • Sensory neurones
        • Carry impulse via a dendron (a feature unique to sensory neurons) from the sense organs to the CNS
          • Can be myelinated
            • Transmit impulses from the CNS to effectors
      • Motor neurones
        • Transmit impulses from the CNS to effectors
    • Nerves
      • Sensory nerves only contain sensory neurons
      • Mixed nerves contain both sensory and motor neurones
      • Motor nerves only contain motor neurons
    • Uses reflex arcs
    • Transmission of nerve impulses
      • Action potentials
        • 1. When a stimulus is detected, Na voltage-gated channels open, Na+ ions come in down their electrochemical gradient
        • 2. Axon membrane is depolarised
        • 3. Na+ channels close while K+ channels opren
        • 4. K+ ions overshoot, membrane becomes hyperpolarised
        • 5. Membrane becomes repolarised
        • 'All-or-nothing' law
        • Refractory period
      • Resting potential
        • -70mV
        • Sodium-potassium pump, 3 Na+ out, 2 K+ in
    • Speed of conduction
      • Depends on whether its myelinated or not
      • Width of axon
      • Saltatory or normal conduction
    • Synapses
      • Transmitter substances
      • Cholinergic synapses
      • Ca2+ ions
      • Inhibitory and excitatory

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