What is the term for the process characterized by the rapid influx of sodium ions into a cell?

The process characterized by the rapid influx of sodium ions into a cell is known as depolarization. During depolarization, when a stimulus reaches a membrane threshold, voltage-gated sodium channels open. This allows sodium ions, which are more concentrated outside the cell, to enter rapidly. As sodium ions flow into the cell, the interior becomes more positive relative to the outside, which disrupts the resting membrane potential. This change is crucial in initiating action potentials in neurons and muscle cells, leading to communication within the nervous system and the contraction of muscles.

Understanding this process is essential in veterinary pharmacology because it underlies the mechanisms of action for many drugs that influence neuronal and muscular activity. In contrast, the other terms refer to different processes: repolarization involves the return to resting potential after depolarization, hyperpolarization refers to the membrane potential becoming more negative, and resting potential is the stable state of the membrane before any action occurs.