Membrane Potential

Membrane Potential (Contd....)

Cellular proteins, phosphate groups and other organic molecules are negatively charged at the intracellular pH. These anions are said to be fixed as they cannot diffuse out of the cell.
As a result these fixed anions attract the positively charged ions from the extracellular fluid that can diffuse into the cell. As the cell membrane is more permeable to potassium, potassium accumulates into the cell. This accumulation continues until an equilibrium between the entry of potassium down the electrical gradient and the exit of potassium down its concnetration gradient, is established. At the concentration of the potassium ion found in the body, the fixed anions are not totally neutralised once the equilibrium is established. Thus a net negative charge exists inside the cell.