MEDICAL PHYSIOLOGY

Detailed explanation-1: -As the equilibrium potential for potassium becomes more positive, the resting potential becomes more positive (i.e., more depolarized). Because of the sodium influx into the cell, the equilibrium potential for sodium is changed, namely, it is less positive.

Detailed explanation-2: -The membrane is permeable to K+ at rest because many channels are open. In a normal cell, Na+ permeability is about 5% of the K+ permeability or even less, whereas the respective equilibrium potentials are +60 mV for sodium (ENa) and −90 mV for potassium (EK).

Detailed explanation-3: -Permeability at Rest Significantly more potassium channels are open than sodium channels, and this makes the membrane at rest more permeable to potassium than sodium.

Detailed explanation-4: -At normal resting membrane potential, sodium is forced outwards and potassium is carry into the cells (see Fig. 2.4). This requires the sodium-potassium exchange pump, which uses ATP in order to operate. Three intracellular sodium ions will be exchanged for every two extracellular potassium ions.