Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2010 Ludek Nerad

Introduction To Action Introduction To Action PotentialPotential

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Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2010 Ludek Nerad

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Content

Terminology

What action potential really means

Where we can find it

Neurones

Networks of neurones

Processing of information

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A temporary reversal in the potential difference across a plasma membrane that occurs when a cell has been activated by a stimulus.

Action potential definition

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Potential energy = potential to deliver work

U = m x g x h

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Tsunami

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U = Q1 x Q2 / r

= 1.5 V

~ 220 V

U … voltage

Q1 … charge

Q2 … charge

r … distance

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Electric potentialis a voltage thatwe measure witha voltmeter.

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Electric potentialis a voltage thatwe measure witha voltmeter.

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Electric potentialis a voltage thatwe measure witha voltmeter.

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Electric currentis a movement offree electrons.

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Ions exert forceon free electronswhich move thevoltmeter pointer.

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Where can we see action potential?

NeuronesPacemakercells

Neuromuscular junction

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Action potentialAction potential

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Conduction in myelinated vs. non-myel. neurones

10 – 120 m/s10 – 120 m/s

5 - 25 m/s5 - 25 m/s

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Saltatory conduction

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5 m5 m18 m18 m

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Synaptic transmission

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