Lecture 7-synaptic integration

Lecture 7-synaptic integration - Synaptic transmission can...

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1 Excitation is the injection of positive charges carried by Na+ ions. The positive charges depolarize the post-synaptic neuron, bringing it closer to threshold or even exceeding threshold thereby generating an action potential. Synaptic transmission can produce either excitation or inhibition in the postsynaptic cell . Inhibition is the injection of negative charges carried either by the influx of Cl- or the efflux of K+ ions. The negative charges hyperpolarize the post-synaptic neuron, thereby taking the membrane potential farther from threshold, and acting to prevent the generation of an action potential.
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2 AP starts here Release of neurotransmitter Excitatory neuron Inhibitory neuron . . . + + + + + + + + + ... Transmitter binds to receptors, opens channels and allows positive Na+ ions to flow into neuron Inject + current + Pre-synaptic neuron Post-synaptic neuron
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3 Excitatory neuron Inhibitory neuron ... -70 mv -75 mv Inject negative current + Pre-synaptic neuron Post-synaptic neuron
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4 + + + -70 mv 0 mv +55 mv threshold Action potential 1 ms Action potential invades terminal + Excitatory Synapse Positive charges carried by Na+ ions
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5 Action potential invades terminal _ -70 mv 0 mv +55 mv inhibition Inhibitory Synapse Negative charges are carried by Cl ions _
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6 Spinal cord _ + extensor muscle now contracts Flexor muscle relaxes because motor neuron that innervates it is inhibited!!!! Excites these neurons Inhibits this neuron
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7
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8 Summation in space of excitatory inputs at different synaptic sites Spatial Summation
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9 -70 mv 0 mv +55 mv Excitatory post-synaptic potential (EPSP) Membrane potential did not reach threshold Excite E1 Excite E1 Alone
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10 -70 mv 0 mv +55 mv Excite E2 Excitatory post-synaptic potential (EPSP) Membrane potential did not reach threshold Now Excite E2 Alone
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11 -70 mv 0 mv +55 mv Now excite E1 and E2 at the same time Excite E1 Excite E2 EPSPs summate And reach threshold Summation in space or Spatial Summation
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This note was uploaded on 10/25/2010 for the course BIO 365R taught by Professor Draper during the Spring '08 term at University of Texas.

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Lecture 7-synaptic integration - Synaptic transmission can...

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