2. The following statement is similar to those you might see on exams. Write a p

Question

2. The following statement is similar to those you might see on exams. Write a paragraph of 3-5 sentences describing 1) whether the statement is correct or incorrect and 2) the reasoning for your answer. Your answer should demonstrate your understanding of the physiological concepts underlying the statement and be professionally written. Assume a cell with the following properties: Nalout- 120 mM; [Nalin 12 mM [Klout 5 mM; [Klin 125 mM Membrane is permeable only to Na and K If the plasma membrane of the cell becomes more permeable to Nat, both influx of Nat into the cell and the Nat equilibrium potential will increase.

Explanation / Answer

Answer: The Statement is incorrect.

Explanation:

Taking the given [Na]out = 120 mM & [Na]in = 12 mM and if the plasma membrane of the celll becomes more permeable to Na+, influx of Na+ will increase but the resulting Na+ equilibrium potential will decrease and not increase. Thus the statement is incorrect.

When [Na]out = 120 mM & [Na]in = 12 mM at physiological temperature, 310.15 K, the equilibrium potential calculated using Nernst Equation will be 61.54 mV.

Now, consider the cell membrane becomes more permeable to Na+ and the influx of Na+ increases.

Due to influx of Na+, say [Na]out becomes 110 mM & [Na]in becomes 22 mM (inflow of 10 mM Na+). At these concentrations of Na+ at physiological temperature, 310.15 K, the equilibrium potential, when recalculated, will be 43.01 mV.

With further influx, let us say [Na]out becomes 100 mM & [Na]in becomes 32 mM (further inflow of 10 mM Na+). Now, the equilibrium potential becomes 30.45 mV.

Thus, at the given [Na]out and [Na]in under physiological conditions, with more and more influx of Na+, the Equilibrium potential of Na+, decreases.

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