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Neurophysiology

Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?

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Page 1: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?

Neurophysiology Neurophysiology

Page 2: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?
Page 3: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?

Membrane Potential

Page 4: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?

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?

Page 9: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?

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

Page 10: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?
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Propagation(fig. 11.13)

Propagation(fig. 11.13)

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ThresholdsThresholds

Page 13: Neurophysiology. Membrane Potential How is the Resting Membrane Potential Changed?

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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