Question

How can the following changes in extracellular sodium and potassium concentrations affect the resting membrane potential? (hint #1: think abou the steepness of the concentration gradient; hint #2: think about the channels that are open when the neuron is at rest) a.Extracellular sodium concentration goes from 150 mM to 50 mM

b. Extracellular potassium concentration goes from 5 mM to 50 mM

Answer 1

Changes in extracellular sodium and potassium concentrations can affect the resting membrane potential of a neuron. Decreasing extracellular sodium concentration reduces depolarization and makes the resting membrane potential more negative. Increasing extracellular potassium concentration hyperpolarizes the membrane and makes the resting membrane potential more negative.

Step-by-step explanation:

Changes in extracellular sodium and potassium concentrations can affect the resting membrane potential of a neuron.

1. Extracellular sodium concentration going from 150 mM to 50 mM: Sodium ions are maintained at high concentrations outside of the cell, and they play a role in establishing the resting membrane potential. If the extracellular sodium concentration decreases, the concentration gradient between the inside and outside of the cell is reduced.

This means that fewer sodium ions will be able to enter the cell, resulting in reduced depolarization and a more negative resting membrane potential.

2. Extracellular potassium concentration going from 5 mM to 50 mM: Potassium ions are maintained at high concentrations within the cell, and they contribute significantly to the resting membrane potential. If the extracellular potassium concentration increases, the concentration gradient between the inside and outside of the cell is increased.

This means that more potassium ions will flow out of the cell, hyperpolarizing the membrane and making the resting membrane potential more negative.