Question

In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The interior is ________.

1) positively charged and contains less sodium
2) negatively charged and contains less sodium
3) negatively charged and contains more sodium
4) positively charged and contains more sodium

Answer 1

The interior surface of a resting neuron's cell membrane is negatively charged and contains less sodium due to the resting membrane potential and the selective permeability of the neuron's cell membrane.

Step-by-step explanation:

The interior surface of a cell membrane of a resting (nonconducting) neuron differs from the external environment in significant ways. The interior is negatively charged and contains less sodium than the external environment.

This state is referred to as the resting membrane potential, typically around -70 millivolts (mV). This electrical charge difference is due to the selective permeability of the neuron's cell membrane, which regulates ion movement, particularly that of sodium (Na+) and potassium (K+) ions.

The presence of sodium-potassium pumps in the cell membrane, which expel three Na+ ions for every two K+ ions brought into the cell, creates a higher concentration of Na+ outside the cell and K+ inside the cell. This pumping action uses ATP for energy and significantly contributes to the overall negative charge inside the cell.