Question

What alters the degree of membrane polarization?

Answer 1

• The influx or efflux of Na and K ions alters the degree of membrane polarizartion.
• During resting membrane potential, usually in negatives- for muscle it is 90mV. there is no change in Na and K in outside the cell and inside the cell.
• By the opening of voltage gated Na+ channels, the influx of Na+ to interior occurs, leading to depolarized state.
• In this stage, the potential increases to +ve values. in muscle it is +35mV, because influx of Na+ caused more positive electrical potential inside of the cell.
• Gradully the closure of this voltage gated Na+ channels and opening of voltage gated K+ channels occur.
• Thus the membrane becomes impermeable to Na + and thus decrease in polarization results - this stage is referred to as repolarization.
• Thus returning back to its intial ppotential.
• But , most often , voltage gated K+ channels remains open even afer the potential reaches the resting membrane potential, hence resulting in more negative potential - referred to as hyperpolarization.
• Finally, 3 Na+ is exchanged with 2K+ to come to restingg membrane potential.