13. Mr. Klaus is trying to maintain a low-sodium diet because of his hypertensio

Question

13. Mr. Klaus is trying to maintain a low-sodium diet because of his hypertension Therefore, he recently switched to using KCI pellets in his water softener, rather than NaCl pellets. While visiting, his 18-month-old grandson Nick accidentally swallowed some of the KCI pellets. The boy was rushed to the hospital, where his plasma potassium was found to be 7.0 mM. Assuming that the boy's other extracellular and intracellular ion concentrations did not change appreciably, and his gK:gNa ratio is normal, which of the following neuronal effects would you expect to occur as a result of the increased plasma potassium? A. The resting gK:gNa ratio would increase. B. EK would be more negative. C. The threshold would be lower (more negative). D. The resting membrane potential would be less negative (depolarized)

Explanation / Answer

D. The resting membrane potential would be less negative( deolarized).

Increase in extracellular potassium concentration causes depolarization of the membrane potential of the cells which takes place as a result of increase in equilibrium potential of potassium.Due to depolarization, some voltage gated sodium channels are opened and there is inactivation also. When the potassium concentration has reached a certain level, it results in inactivation of sodium channels and opening of the potassium channels, which leads to the cell being refractory.The resting membrane potential becomes closer to the threshold of action potential which increases the excitability of the cells.

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