What hormone is secreted by the adrenal medulla in response to stress?

The hormone secreted by the adrenal medulla in response to stress is adrenaline, also known as epinephrine. This hormone plays a critical role in the body's "fight or flight" response, which prepares the individual to react to stressful situations. When faced with stress, the adrenal medulla releases adrenaline into the bloodstream, leading to various physiological changes. These changes include increased heart rate, elevated blood pressure, enhanced energy production, and heightened alertness, all of which are geared towards improving the body’s ability to respond to a perceived threat.

Adrenaline acts quickly and has a relatively short duration of action, making it essential for acute stress responses. This hormone works in conjunction with norepinephrine, which is also released during stress but by different mechanisms and has longer-lasting effects on other parts of the nervous system.

In contrast, cortisol, which is produced by the adrenal cortex, is involved in the longer-term response to stress and metabolism regulation, making it less immediate in its effects compared to adrenaline. Thyroxine, primarily produced by the thyroid gland, regulates metabolism but is not directly involved in the acute stress response mediated by the adrenal medulla.