Question

If a cell's Na+/K+ pump worked in reverse and had more leak channels for Na+ than for K+, what would the ion concentrations of the cell look like?

A) Intracellular Cl- would be increased, following Na+.

B) Intracellular concentration of K+ would still be higher than Na+ because the body tries to maintain an extracellular concentration of Na+ at 145 mM.

C) Although the body tries to maintain an extracellular concentration of Na+ at 145mM, the intracellular concentration of Na+ would still be higher.

D) Intracellular anions would decrease in number.

E) The cell would swell since water follows Na+ .

Answer 1

If the Na+/K+ pump operated in reverse with more Na+ leak channels than K+, there would likely be increased intracellular Na+ leading to increased Cl- and potentially cell swelling due to water following Na+. Common body regulation mechanisms would not prevent the rising intracellular Na+. Choices A) and E) offer plausible outcomes.

Step-by-step explanation:

If a cell's Na+/K+ pump worked in reverse and there were more leak channels for Na+ than for K+, the concentration gradients of these ions would be affected significantly. Normally, the Na+/K+ pump works to maintain a high concentration of K+ inside the cell and a high concentration of Na+ outside the cell by pumping three Na+ ions out and two K+ ions in, consuming one molecule of ATP in the process. This activity also contributes to the negative charge inside the cell due to the net loss of one positively charged ion per cycle of the pump.

However, if this pump were to reverse function, there would be an influx of Na+ ions into the cell and an efflux of K+ ions, disrupting the normal electrochemical gradient. The intracellular Na+ concentration would increase and the K+ concentration would decrease. Given that the cell has more leak channels for Na+ under these conditions, even more Na+ ions would enter, further increasing the intracellular Na+ concentration. Opposite to normal conditions, where Cl- follows Na+ to maintain electrical neutrality, increased intracellular Na+ may lead to an increase in intracellular Cl-. This situation would lead to the answer choice A) Intracellular Cl- would be increased, following Na+.

Despite the body's regulatory mechanisms to maintain extracellular Na+ at around 145mM, these mechanisms could not prevent the rising intracellular Na+ in the scenario described. So, answer choice B) is incorrect, as intracellular K+ would not necessarily remain higher than Na+, especially in the context of the pump reversal. Similarly, answer choice C) is incorrect, as it suggests the intracellular Na+ concentration would be higher, which contradicts the typical function of the Na+/K+ pump. Answer choice D) is counterintuitive, as increased Na+ within the cell would likely attract more anions, not decrease them. Lastly, answer choice E) suggests the cell would swell due to water following Na+, which is a plausible outcome as osmosis tends to move water towards higher solute concentrations.