OSMT (Ontario Society of Medical Technologists) Practice Exam

During the depolarization of a neuron, sodium ions:

1. a. Stay outside of the cell

2. b. Rush out of the cell

3. c. Stay inside of the cell

4. d. Rush into the cell

The correct answer is: d. Rush into the cell

The correct answer is that sodium ions rush into the cell during the depolarization of a neuron. This process is a critical part of the action potential in neurons. When a neuron is stimulated, the ion channels in the neuron's membrane open, allowing sodium ions, which are more concentrated outside the cell, to flow rapidly into the cell. This influx of positively charged sodium ions causes the inside of the neuron to become more positive compared to the outside, leading to depolarization. The movement of sodium ions is essential for the transmission of electrical signals within the nervous system. This change in membrane potential ultimately triggers further signaling down the neuron and the release of neurotransmitters at the synapse. Options suggesting that sodium ions stay outside, rush out, or stay inside do not accurately represent the physiological process that occurs during depolarization. Sodium ions must enter the cell to create the changes in electrical potential necessary for neuronal signaling.