The Nervous System

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The Nervous System
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Neurons are highly specialized cells.

• A neuron has three parts.
• cell body has nucleus and organelles

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Neurons are highly specialized cells.

• A neuron has three parts.
• cell body has nucleus and organelles

• dendrites receive impulses as signals (message)

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Neurons are highly specialized cells.

• A neuron has three parts.
• cell body has nucleus and organelles

• dendrites receive impulses as signals (message)

• axon carries impulses as signals

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• Neurons have other structures to transmit signals.

• Schwann cell, makes up myelin sheath, which
  insulates axons

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• Neurons have other structures to transmit signals.

• Schwann cell, makes up myelin sheath, which
  insulates axons

• Synapse, which is the gap between neuron and next
  cell

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• Neurons have other structures to transmit signals.

• Schwann cell, makes up myelin sheath, which
  insulates axons

• synapse, which is the gap between neuron and next
  cell

• Terminal is where the signal leaves

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Resting Potential

• Defined Neuron at rest
• Neuron Exterior
• Positive charge
• Mainly Na outside the cell
• Neuron Interior
• Negative charge
• K inside the cell

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• An action potential is a moving electrical
  impulse.

• It is generated by a stimulus.
• Na enters, and cell becomes positively charged.
• K leaves, and area of positive charge moves.

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impulse
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negative impulse
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Synapse

• Defined Gap between neurons
• Problem Impulse cannot cross the gap
• Solution Impulse converted into chemical
  molecules that stimulate the next cell, called
  neurotransmitters
• Steps
• Impulse reaches neurons end
• Vesicle releases neurotransmitters
• Neurotransmitters attach to neighboring neuron
• New impulse created

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Impulse stimulates a vesicle, which contains
neurotransmitters
Vesicle exits the cell and dissolves
impulse
Start of another cell
End of one cell
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Neurotransmitters stimulate a new impulse
Neurotransmitters cross the synapse and attach to
receptors of a neighboring neuron
impulse
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Start of another cell
End of one cell
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Brain
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Feet
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Motor neurons reach the muscles

• Impulse causes the muscles to stretch and
  contractthis causes MOVEMENT!