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Nerve Impulses

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and from one neuron to the next? ... The resting membrane potential is ... axon of a pre-synaptic neuron & a dendrite or cell body of a post-synaptic neuron. ... – PowerPoint PPT presentation

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Title: Nerve Impulses


1
Nerve Impulses
2
How is information transmitted within one
neuron?..and from one neuron to the next?
3
  • resting state, the neuron is more negative inside
    compared to outside. The resting membrane
    potential is -70 millivolts (mV). The reason for
    this is because of the distribution of charged
    ions

4
  • Sodium (Na) and potassium (K) are positive
    ions.
  • They are found on both sides of the membrane.
  • More Na ions on outside
  • K ions are more concentrated inside the neuron.
  • Unequal pumping (3 Na out to 2K in)

5
  • Stimulation of neuron results in Na gates open
    allowing Na to rush in
  • Depolarization of the membrane in the area where
    the stimulation occurred.
  • Depolarization of an area of membrane stimulates
    more Na gates in adjacent areas to open, thus
    spreading the depolarization.

6
  • Immediately after depolarization, Na channels
    close and K channels open causing K to flow
    out.
  • This process returns positive charge to the area
    just outside the membrane, thus restoring the
    resting polarity.

7
What happens when the impulse reaches the end of
the axon?
  • Synapse point of impulse transmission between
    neurons. The synaptic gap\cleft is a small gap
    separating neurons.

8
A synapse
  • occurs between the axon of a pre-synaptic neuron
    a dendrite or cell body of a post-synaptic
    neuron.
  • neurotransmitters are chemicals released from one
    neuron at the presynaptic nerve terminal.

9
  • Neurotransmitters cross the synapse where they
    may be accepted by the next neuron at a
    specialized site called a receptor.

10
Neurotransmitter Substances
  • Acetylcholine (ACh)
  • Dopamine (DA)
  • Norepinephrine (NE)
  • Serotonin (5-HT)
  • Histamine
  • Epinephrine

11
Excitatory and inhibitory postsynaptic potentials
  • A synaptic potential can be excitatory or
    inhibitory
  • There are more
  • than 50
  • different
  • neurotransmitters.

12
The big picture
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