Patient Care Technician (PCT) AAH Practice Exam

Which electrolyte is essential for the activity of neurons and muscle cells?

1. Magnesium

2. Calcium

3. Sodium

4. Potassium

The correct answer is: Potassium

Potassium plays a crucial role in the activity of both neurons and muscle cells due to its involvement in generating and propagating action potentials. In neurons, the influx and efflux of potassium ions are fundamental processes in the transmission of electrical signals. When a neuron is activated, sodium ions rush in, leading to depolarization, but the restoration to the resting membrane potential involves potassium ions moving out of the cell. This exchange is essential for the rapid rise and fall of the electrical charge across the neuron's membrane, allowing it to effectively relay signals. In muscle cells, potassium also contributes significantly to the contraction process. The relative concentrations of sodium and potassium across the cell membrane are key in the action potential generation that triggers muscle contraction. This ion transport is crucial for the proper functioning of both neuron signaling and muscle contraction, highlighting potassium's essential role in these physiological processes.