AAMC FL Practice Exam

What is the primary function of the Na+/K+ ATPase pump?

1. Transporting glucose across the membrane

2. Regulating calcium levels in the cell

3. Maintaining the resting membrane potential

4. Transporting sodium out and potassium into the cell

The correct answer is: Transporting sodium out and potassium into the cell

The primary function of the Na+/K+ ATPase pump is to transport sodium ions out of the cell while bringing potassium ions into the cell. This active transport mechanism is crucial for maintaining the appropriate concentration gradients of these ions across the plasma membrane. By moving three sodium ions out of the cell for every two potassium ions it brings in, the pump not only helps to balance ion concentrations but also plays a critical role in maintaining the resting membrane potential. The action of the pump creates a net negative charge inside the cell relative to the outside, which is vital for the normal functioning of neurons and muscle cells, allowing them to respond to stimuli. This movement directly influences the excitability of cells and is essential in processes such as nerve impulse conduction and muscle contraction. Therefore, the pump's function is fundamental to cellular homeostasis and electrochemical gradients that support various physiological processes.