NERVE%20IMPULSE

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NERVE IMPULSE
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NERVE IMPULSE

• An electric message sent on neurons. 4 stages of
  sending message.

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STEP 1

• Resting potential -70 mV (millivolts) difference
  between inside and outside.
• Na ions outside
• K and Proteins inside.

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STEP 2

• Action potential Membrane stimulated
• Na gates open (come in)
• Depolarization (30 mV)

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Step 3

• Repolarization
• K ions gates open (go out)
• Returns to -70 mV

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Step 4

• Recovery
• Na/K pumps use ATP (energy) to pump back to
  original places.
• Shuts down until complete!

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CONDUCTION

• The nerve impulse travels like a wave.
• 2 different methods.

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CONDUCTION

• Myelinated impulse jumps from node to node.
  FASTER (100-200m/sec)

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CONDUCTION

• UN-myelinated impulse goes from point to point.
  SLOWER (1m/sec)

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• Look at your textbook example on page 223

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• Synaptic Transmission

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Synaptic Transmission

• Chemical message going from one neuron to another.

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SYNAPSE

• Where impulse crosses gap by changing from
  electric ? chemical ? electric

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COLOR CODE

• Please color code the synapse
• B, I, g, j, h, k

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Synaptic knob

• B. Enlarged end of the axon.

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Synaptic Cleft

• i. The gap between dendrite and knob.

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Synaptic Vesicle

• G. Hold chemical neurotransmitter.

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Neurotransmitter

• J. Chemical released to cross cleft and start
  impulse.
• Aceytlcholine (Ach)
• Page 216

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Presynaptic Membrane

• H. Membrane of axon before Cleft.

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Postsynaptic Membrane

• K. Membrane of dendrite AFTER cleft.
• Contain receptor sites for neurotransmitter.

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EVENTS

• There are basically seven steps that happen when
  a signal is sent over the synaptic cleft.

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EVENTS

• 1. Action potential arrives at synaptic knob
  (30mV)

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EVENTS

• 2. Ca ions flow into the synaptic knob.

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EVENTS

• 3. Vesicles merge with pre-synaptic membrane and
  release neurotransmitter.

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EVENTS

• 4. Neurotransmitter (Ach) diffuses across cleft
  (key).

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EVENTS

• 5. Neurotransmitter binds with receptor (lock) on
  postsynaptic membrane.

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EVENTS

• 6. Na gates open and action potential begins.

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EVENTS

• 7. Neurotransmitter broken down by enzyme (Ache).
• Gates close.

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