Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?
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Transcript of Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?
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Neurophysiology Neurophysiology
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Membrane Potential
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How is the Resting Membrane Potential Changed?
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Changes in Membrane Potential
• From -70 mV to +30 mV
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Channels and Changes in the Membrane Potential
Chemically Gated Channels Chemically Gated Channels
Voltage-Gated Channels Voltage-Gated Channels
When these gates are opened, ions move down their electrochemical gradient!When these gates are opened, ions move down their electrochemical gradient!
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How are Graded Potentials Different from Action Potentials?
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Only occur in ‘excitable membranes’Muscle cells Neurons Axon Hillock
Graded potentials may turn into action potentialsSummation
○ Temporal and Synaptic
Comments Strength does not decreaseSelf propagating
Only occur in ‘excitable membranes’Muscle cells Neurons Axon Hillock
Graded potentials may turn into action potentialsSummation
○ Temporal and Synaptic
Comments Strength does not decreaseSelf propagating
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Propagation(fig. 11.13)
Propagation(fig. 11.13)
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ThresholdsThresholds
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Ion channels - openNeuron cannot respond to another stimulus Na+ channels must close first!
○ Resets normal polarized state
Types AbsoluteRelative
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Pre-Synaptic and Post-Synaptic Activity
• Depolarization waves– Moves towards the synapse
• Conduction speed depends on – Diameter of axon– Myelination
• Nerve Fiber Types– Group A, B, C
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Saltatory Conduction
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When the Nerve Transmission Reaches the Synapse
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Electrical Synapse – less common; coordinate neuron activity between neurons; ions move through gap junctions; most abundant in embryonic tissue; brain find stereotyped movements (hippocamus); glial cells of CNS
Chemical Synapses – ions flow between channels; Neurotransmitters are released
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Chemical Synapse
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At the Synapse
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Summation
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• Neurons of CNS – neuronal pools – Integrate incoming information
• Neurons of CNS – neuronal pools – Integrate incoming information
1. Discharge zone 2. Facilitated zone 1. Discharge zone 2. Facilitated zone
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Neural Circuits
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