NERVE IMPULSE

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NERVE IMPULSE
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Resting Potential

• When no impulse is occurring along neuron.
• Potential refers to differences in charges inside
  and outside the membrane.

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Distribution of charge

• Positive charges are on the outside of neuron.
• Negative charges are on the inside of neuron.

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Sodium / Potassium pump

• Due to more Na on outside more K on the
  inside.
• Negative protein ions on inside.
• The neuron is said to be polarized.
• This is due to the Na/K pump.

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Action Potential

• Voltage gated channels open.
• Na moves in.
• K moves out
• Proteins stay inside

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depolarization

• Charges reverse.
• Outside turns negative.
• Inside turns positive.
• This is how the nerve sends a signal through
  electrical impulses.

Pair share do you think it take energy for the
cell to reverse the charge after an impulse is
sent? Why?
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Refactory Period

• Period of time after depolarization when neuron
  cannot create action potential.
• Voltage gated channels close.
• Sodium/potassium pump must create resting
  potential.
• Uses ATP to do this.
• Neuron is now back to resting potential.

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Neuron Structure

• The space between neurons is called the synapse.
• (Synaptic cleft)

Synapse
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neurotransmitter

• The action potential is transferred across the
  synapse by a chemical neurotransmitter.
• The neurotransmitter is released from vesicles in
  the axon.
• The neurotransmitter is released when the action
  potential reaches the axon terminal.

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Review

1. What is the charge inside the neuron when it is
   at resting potential?
2. What is the purpose of the Na / K pump?
3. What moves across the synapse?