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 standard voltage of a neuron's resting membrane potential is -70 mV.

This potential arises from disparities in ion concentrations (primarily K⁺ and Na⁺) across the neuronal membrane, actively managed by ion pumps and channels.

Factors influencing resting membrane potential:

• Ion Concentration Gradients: Neurons exhibit higher internal K⁺ concentration and higher external Na⁺ concentration. The Na⁺/K⁺ ATPase pump maintains these gradients by extruding three Na⁺ ions for every two K⁺ ions pumped inward.
• Selective Permeability: The neuronal membrane is significantly more permeable to K⁺ than Na⁺ due to a greater number of K⁺ channels. This leads to a net outward movement of K⁺, establishing a negative charge within the cell relative to the exterior.
• Electrochemical Equilibrium: The resting membrane potential signifies an electrochemical equilibrium. The electrical forces attracting K⁺ inward are counterbalanced by the concentration forces driving K⁺ outward. This K⁺ equilibrium is instrumental in setting the negative resting potential.

Key Information:

• The resting membrane potential typically hovers around -70 mV, with minor variations based on neuron type and conditions.
• This potential is fundamental to neuronal function, priming neurons for action potentials, the electrical signals used for intercellular communication.
• The resting potential is not zero, reflecting a stable, albeit slightly negative, internal cellular charge relative to the outside.

The resting membrane potential is a critical element of neuronal excitability and is involved in the generation and propagation of action potentials during neural signaling.