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Impulse propagation/local circuits and repolarisation

Human Anatomy, Physiology, and Medicine. Anything human!

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Impulse propagation/local circuits and repolarisation

Postby ADAS137 » Sat Dec 31, 2011 4:16 pm

I'm a little confused about repolarisation and its link with local circuits.

As far as i'm aware, repolarisation is due to K+ channels opening, thus outflow causes a fall back to membrane potential.

Local circuits are caused because, the influx of sodium ions is attracted to the surrounding negative regions, they then move to the negative region ahead (not behind as in refractory period) which causes depolarisation etc and the process repeats.

What i'm thinking is....does the very movement of the sodium ions, due to the local circuits, not cause repolarisation? Surely if lots of positive ions flow away, that's going to causes the region to become more negative=repolarisation?
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Postby JackBean » Tue Jan 31, 2012 3:04 pm

first sodium flows inside and cause depolarization (because the membrane is already polarized)
then the potassium gets outside and causes repolarization (the action potential gets back to starting value)

during resting the concentrations of Na+ and K+ are renewed.
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