What happens when a resting neuron's membrane depolarizes? a. There is a net diffusion of Na+ out of the cell. b. The equilibrium potential for K+(EK) becomes more positive. c. The neuron's membrane voltage becomes more positive. d. The cell's inside is more negative than the outside.

Verified step by step guidance

1. Step 1: Understand the question. The question is asking what happens when a resting neuron's membrane depolarizes. Depolarization is the process by which the membrane potential of a cell becomes less negative or more positive.
2. Step 2: Review the options. Option a suggests that there is a net diffusion of Na+ out of the cell. This is incorrect because during depolarization, Na+ ions actually rush into the cell, not out of it.
3. Step 3: Consider option b. This option suggests that the equilibrium potential for K+ (EK) becomes more positive. This is incorrect because the equilibrium potential for K+ does not change during depolarization. Instead, the membrane potential moves closer to the equilibrium potential for Na+.
4. Step 4: Look at option c. This option suggests that the neuron's membrane voltage becomes more positive. This is correct. During depolarization, the membrane potential becomes less negative (or more positive) due to the influx of Na+ ions into the cell.
5. Step 5: Finally, consider option d. This option suggests that the cell's inside is more negative than the outside. This is incorrect because during depolarization, the inside of the cell becomes less negative (or more positive) due to the influx of Na+ ions.

Key Concepts

Neuronal Membrane Potential

The neuronal membrane potential refers to the voltage difference across a neuron's membrane, primarily influenced by the distribution of ions, particularly sodium (Na+) and potassium (K+). At rest, a neuron has a negative membrane potential, typically around -70 mV, due to the higher concentration of K+ inside the cell and Na+ outside. Changes in this potential are crucial for neuronal signaling.

Depolarization

Depolarization is the process by which the membrane potential of a neuron becomes less negative (or more positive) than its resting state. This occurs when sodium channels open, allowing Na+ ions to flow into the cell, leading to a shift in the membrane voltage. This change is essential for the generation of action potentials, which are the signals that neurons use to communicate.

Equilibrium Potential

The equilibrium potential is the membrane voltage at which there is no net movement of a particular ion across the membrane, as the chemical and electrical gradients are balanced. For potassium (K+), this potential (EK) is typically negative, and during depolarization, the membrane potential can approach this value, affecting the overall excitability of the neuron and its ability to fire action potentials.