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Describing a Purely Capacitive Membrane injected with a constant Current

  1. Sep 11, 2011 #1
    Hi PS users,

    I am trying to explain to some students why, when you inject a neurone with a constant current intracellularly, the membrane potential charges linearly, until the injected current is removed, at which point the membrane potential becomes flat.

    To put this in circuitry terms: why, when you have a purely capacitive circuit (capacitor and a battery, say), does the potential difference across the capacitor increase linearly?

    I have written an explanation, which is in terms of the membrane of a neurone and is attached. To explain this example, as this is how I wish to explain the phenomenon, inside and outside of a neurone is a 'liquid' of positively charge ions, and so the impermeable membrane of the neurone, has a potential difference across it. The impermeable membrane of the neurone also acts a capacitor. When you inject a current into the inside of the neurone, the membrane potential of the cell increases linearly until you remove the injected current.



    Attached Files:

  2. jcsd
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