Ca2+ diffusion results in which change to the intracellular charge?

Ca2+ diffusion results in which change to the intracellular charge?

• A. More positive inside
• B. More negative inside
• C. No change
• D. More positive outside

Answer: (A)

Ca2+ carries a +2 charge, and its diffusion into the cell brings positive charges into the cytosol. Since the inside of the cell contains fixed negative components, entry of Ca2+ makes the intracellular milieu less negative and more positive, effectively depolarizing the membrane. So the intracellular charge becomes more positive. (Diffusing outward or no movement would not produce this change.)

Ca2+ carries a +2 charge, and its diffusion into the cell brings positive charges into the cytosol. Since the inside of the cell contains fixed negative components, entry of Ca2+ makes the intracellular milieu less negative and more positive, effectively depolarizing the membrane. So the intracellular charge becomes more positive. (Diffusing outward or no movement would not produce this change.)