Adrenaline instantly widens your airways to maximize oxygen intake during stress.

Adrenaline, also called epinephrine, is a hormone produced by the adrenal glands sitting atop your kidneys. When you perceive a threat, your amygdala signals the hypothalamus, which activates your sympathetic nervous system and triggers adrenaline release into the bloodstream within seconds.Once in circulation, adrenaline binds to beta-2 adrenergic receptors on the smooth muscle cells lining the bronchioles in your lungs. This binding relaxes these muscles in a process called bronchodilation, widening the airways and reducing resistance to airflow. The result is significantly increased oxygen reaching the alveoli for gas exchange.Harvard physiologist Walter Cannon famously described this response in the early 20th century. The rapid oxygen increase is vital for ATP production in muscles, providing the energy needed to fight or flee. During anaphylaxis, the immune system causes dangerous airway constriction.The EpiPen, patented by Sheldon Kaplan in 1977, delivers 0.3 milligrams of synthetic epinephrine to reverse this constriction. By mimicking your body's natural adrenaline response, it forces airways open and stabilizes blood pressure, demonstrating how a natural survival mechanism becomes a life-saving medical tool.