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NERVE IMPULSE
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An electric message sent on neurons. 4 stages of sending message.
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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Action potential: Membrane stimulated Na+ gates open (come in)
STEP 2 Action potential: Membrane stimulated Na+ gates open (come in) Depolarization (+30 mV)
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K+ ions gates open (go out) Returns to -70 mV
Step 3 Repolarization: K+ ions gates open (go out) Returns to -70 mV
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Na/K pumps use ATP (energy) to pump back to original places.
Step 4 Recovery: Na/K pumps use ATP (energy) to pump back to original places. Shuts down until complete!
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The nerve impulse travels like a wave. 2 different methods.
CONDUCTION The nerve impulse travels like a wave. 2 different methods.
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Myelinated: impulse jumps from node to node. FASTER (100-200m/sec)
CONDUCTION Myelinated: impulse jumps from node to node. FASTER ( m/sec)
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UN-myelinated: impulse goes from point to point. SLOWER (1m/sec)
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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B. Enlarged end of the axon.
Synaptic knob B. Enlarged end of the axon.
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i. The gap between dendrite and knob.
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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H. Membrane of axon before Cleft.
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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