Which hormone is primarily produced by the adrenal medulla during a stress response?

The hormone primarily produced by the adrenal medulla during a stress response is epinephrine, also known as adrenaline. When faced with stress, the body activates the sympathetic nervous system, prompting the adrenal medulla to release epinephrine into the bloodstream. This hormone plays a crucial role in the "fight or flight" response—an evolutionary adaptation that prepares the body to respond to perceived threats.

Epinephrine increases heart rate, dilates air pathways, and enhances blood flow to critical areas like muscles, thereby preparing the body for rapid action. It also stimulates the release of glucose from energy stores, providing an immediate source of energy for heightened physical performance.

In contrast, cortisol, while released by the adrenal glands, is produced in the cortex rather than the medulla and primarily acts as a long-term stress hormone. Testosterone is mainly associated with male reproductive functions and has no direct role in acute stress responses. Insulin, produced by the pancreas, regulates blood sugar levels but is not involved in the immediate stress response linked to the adrenal medulla. Understanding these distinctions clarifies why epinephrine is the key hormone released during acute stress.