The membrane potential of a cell is 70mV ENa is 65 mV EK 95

The membrane potential of a cell is -70mV. ENa is +65 mV, EK = -95 mV, ECl = -75 mV.

a)Only Na channels open. In which direction would Na+ go? Is this negative or positive

current?

b)Only K channels open. In which direction would K+ go? Is this negative or positive current?

c)Only Cl channels open. In which direction would Cl- go? Is this a negative or positive

current?

Solution

a)When the sodium channels open in the membrane of conducting cells with membrane potential=-70mV, and electrode potential of sodium ion=65mV ,and electrode potential of potassium cell=-95mV, electrode potential of chloride ion=-75mV, then the sodium ions will move from outside the cell to the inside of the cell, leading to a positive current flow.

b)when potassium channel is open, the potassium ions will move from inside the cell membrane to outside the cell membrane, which is again a positive current.

c)when chloride channels open,the chloride ions move from outside the cell to the inside of the cell, which is defined as the negative current.