What is the primary hormone secreted by the adrenal glands during stress?

The primary hormone secreted by the adrenal glands during stress is adrenaline, also known as epinephrine. This hormone plays a crucial role in the body's "fight or flight" response, rapidly preparing the body for stressful situations by increasing heart rate, blood flow to muscles, and energy availability. When faced with stress, the adrenal glands release adrenaline into the bloodstream, which prompts immediate physiological changes that enhance an individual’s ability to respond to a perceived threat.

While cortisol is also an important hormone produced by the adrenal glands in response to chronic stress, its effects are more focused on metabolic processes and immune response regulation rather than immediate reactions. Therefore, although cortisol is critical for the body's long-term stress adaptation, adrenaline is primarily responsible for acute stress responses. Other hormones like norepinephrine also play a role in the stress response, but adrenaline is the key player that triggers the rapid reactions necessary in stressful situations. Insulin, in contrast, is involved in blood sugar regulation and is not directly related to the stress response.