Question

How does the cell maintain its resting membrane potential?

1) By exporting 3 Na⁺ from the cell in exchange for 2 K⁺
2) By opening sodium and potassium leak channels in the plasma membrane
3) By allowing Na⁺ and K⁺ to move down their concentration gradients
4) All of the above

Answer 1

A neuron at rest is negatively charged due to differences in ion concentrations and selective permeability. The cell maintains its resting membrane potential through active transport, leakage channels, and concentration gradients of ions.

Step-by-step explanation:

A neuron at rest is negatively charged: the inside of a cell is approximately 70 millivolts more negative than the outside (-70 mV). This voltage is called the resting membrane potential. It is caused by differences in the concentrations of ions inside and outside the cell and the selective permeability created by ion channels.

The cell maintains its resting membrane potential by a combination of factors. First, the sodium-potassium pump actively transports three sodium ions out of the cell for every two potassium ions in, creating a net negative charge inside the cell. Second, there are potassium leakage channels that allow potassium ions to freely move out of the cell. Third, the selective permeability of the cell membrane allows for the movement of sodium and potassium ions down their concentration gradients.

Therefore, the cell maintains its resting membrane potential by exporting sodium ions, allowing potassium ions to slowly move out of the cell through leakage channels, and allowing ions to move down their concentration gradients. So the correct answer is option 4) All of the above.