Describe the effects of adrenaline and explain its usefulness?

Adrenaline, also known as epinephrine, is a hormone and neurotransmitter that prepares the body for a "fight or flight" response during stressful situations. It increases heart rate, expands airways, and boosts energy availability by mobilizing glucose and fatty acids. This physiological response enhances alertness, improves reaction time, and can ultimately be lifesaving in emergencies. Its usefulness is evident in medical treatments, such as in anaphylaxis, where it rapidly counteracts severe allergic reactions.