Key Concepts in Neurophysiology and Sensory Systems

Which of the following best explains why sodium ions (Na+) are crucial for the initiation of action potentials in neurons? Correct answer: Their influx depolarizes the membrane, triggering the action potential.

A patient is exposed to a toxin that causes prolonged opening of chloride channels in their neurons’ postsynaptic membranes. What is the most likely effect on neuronal activity? Correct answer: The neuron will become hyperpolarized and less likely to fire action potentials.

During which period is a neuron able to generate another action potential only if a much stronger than normal stimulus is applied, and what is the main ionic movement responsible? Correct answer: Relative refractory period; efflux of potassium ions.