What hormone is primarily released by the adrenal glands during stress responses?

The hormone primarily released by the adrenal glands during stress responses is epinephrine, also known as adrenaline. When the body encounters a stressful situation, the adrenal glands, specifically the adrenal medulla, secrete epinephrine into the bloodstream. This hormone plays a crucial role in the "fight or flight" response, preparing the body for a rapid reaction to threats.

Epinephrine triggers various physiological changes. It increases heart rate and blood pressure, dilates the airways, and boosts energy supplies by increasing blood glucose levels. These changes collectively enhance the body's ability to respond immediately to stressors.

In contrast, cortisol, although released during stress, is a steroid hormone that contributes to long-term stress responses and helps regulate metabolism and the immune response. Serotonin is primarily a neurotransmitter related to mood and appetite regulation, while insulin is involved in glucose metabolism and is not primarily associated with the stress response. Understanding the role of epinephrine is key in recognizing how the body reacts under stress and the importance of immediate physiological adaptations.