Question

In which direction will Ca2+ flow if both intracellular concentrations and extracellular concentrations are 1mM? Assume the plasma membrane is permeable to Ca2+.

a. Ca2+ will flow into the cell

b. Ca2+ will flow out of the cell

c. There will be no net flux of Ca2+ in or out of the cell

d. It depends on the membrane potential, not enough information is provided to answer the question

Answer 1

Option c is the ct answer. Here, the plasma membrane is permeable to Ca2+ and in this condition the flow of Ca2+ will occur only if a concentration difference will be present between extracellular and intracellular environment.

Note: In general condition the cell membrane is not permeable to Ca2+. In resting membrane potential stage the extracellular concentration of Ca2+ is 10000 times higher outside the cell in comparison to inner side. This difference is maintained by active calcium pumps. When a stimulus occurs to the cell, the calcium channel opens and Ca2+ ions rush into the cell due to huge concentration difference which may results into various physiological responses.