Question

What is the typical voltage of the resting membrane potential in a neuron?

• A. +70 mV
• B. -70 mV
• C. 0 mV
• D. +30 mV

Hint:

The resting potential is maintained by the sodium-potassium pump (Na⁺/K⁺ ATPase), which moves sodium out and potassium in to keep the cell's charge difference stable.

Answer 1

The Correct Option is B

The typical voltage of the resting membrane potential in a neuron is -70 mV (millivolts).

This resting membrane potential is a result of the difference in ion concentrations across the neuronal cell membrane, primarily involving potassium ions (K⁺) and sodium ions (Na⁺), and is maintained by ion pumps and channels.

Factors contributing to the resting membrane potential:

• Ion Concentration Gradients: The neuron has a higher concentration of potassium ions inside the cell and a higher concentration of sodium ions outside the cell. This gradient is established by the sodium-potassium pump (Na⁺/K⁺ ATPase), which actively transports three sodium ions out of the cell for every two potassium ions it pumps in, maintaining these concentration differences.
• Selective Permeability: The neuronal membrane is more permeable to potassium ions than sodium ions due to the presence of more potassium channels. This results in a net movement of potassium ions out of the cell, leaving behind a negative charge inside the cell relative to the outside.
• Electrochemical Equilibrium: The resting membrane potential represents a state of electrochemical equilibrium, where the electrical forces pushing potassium ions into the cell are balanced by the concentration forces pushing potassium ions out of the cell. This equilibrium for potassium helps establish the negative resting potential.

Key Points:

• The resting membrane potential is typically around -70 mV, though it can vary slightly depending on the type of neuron and the specific conditions.
• It is essential for the function of neurons, as it sets the stage for action potentials, which are the electrical signals that neurons use to communicate with one another.
• The resting potential is not "zero," indicating that there is a stable, but slightly negative charge inside the neuron relative to the outside.

This resting membrane potential is a crucial aspect of neuronal excitability and is involved in the generation and propagation of action potentials during nerve signaling.