acintya
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The K+ concentration gradient is the most important factor that conrols resting membrane potential. K+ is needed to repolarize the cell membrane to a resting state after an action potential has passed.
The membrane potential (in nerve cells) for K+ is -90mV==> the inside surface of the membrane is MORE NEGATIVE compared to the outside.
Ventricular repolarization produces the T wave; which happens because the Voltage gated K+ channels are opening, and increases the K+ conductance, (now the cell is more POSITIVE than the outside) so there is RAPID EFFLUX of K+ ==> Repolarization of the resting membrane potential.
When there is increased extracellular K+ (Hyperkalemia); the inside of the cell becomes LESS NEGATIVE compared to the outside---> this causes a DEPOLARIZATION instead of the usual repolarization [ie Membrane potential moves in a +ve direction] and you see the Peaked T wave.
When there is decreased extracellular K+ (Hypokalemia); the inside of the cell becomes MORE NEGATIVE than the outside, ---> more efflux of K+==> Hyperpolarization of the resting membrane potential---> and you see a U wave AFTER the T wave.
I hope this makes sense....anyone else wants to discuss this?
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