Advanced Placement (AP) Biology 2026 – 400 Free Practice Questions to Pass the Exam

Epinephrine, also known as adrenaline, is a hormone that plays a crucial role in the body's response to stress and emergency situations. It is released by the adrenal medulla during stressful events—often referred to as the "fight or flight" response. When released into the bloodstream, epinephrine leads to various physiological changes that prepare the body to respond to imminent threats. These changes include increased heart rate, elevated blood pressure, dilation of the airways, and enhanced energy availability through the mobilization of glucose and fatty acids.

This hormone essentially primes the body for immediate physical action, making it key in emergency situations where quick responses are necessary for survival. The other hormones mentioned have different roles: insulin regulates blood sugar levels, cortisol is critical for long-term stress responses and metabolism, while testosterone primarily influences reproductive functions and muscle mass.