Question

Where should most of the potassium ions be located when a muscle cell is at rest?

A) cytosol of the muscle cell
B) extracellular fluid
C) sarcoplasmic reticulum
D) tranverse tubules (T-tubules)

Answer 1

Answer

Step-by-step explanation:

When a muscle cell is at rest, most of the potassium ions should be located in the (A) cytosol of the muscle cell. During rest, the concentration of potassium ions is typically higher inside the cell compared to the extracellular fluid. This concentration gradient is maintained by the action of ion pumps, such as the sodium-potassium pump, which actively transports potassium ions into the cell and sodium ions out of the cell. As a result, the cytosol of the muscle cell contains a higher concentration of potassium ions, while the extracellular fluid has a lower concentration. The sarcoplasmic reticulum and transverse tubules (T-tubules) play roles in muscle contraction and calcium ion release, rather than potassium ion distribution during resting conditions.