Adrenaline is a powerful chemical your body releases when you're scared, excited, or facing danger. The moment you realize you're about to crash on your bike, or when you step up to bat with the game on the line, adrenaline floods your system.

Your body produces adrenaline in small organs called adrenal glands, which sit on top of your kidneys. When your brain detects something threatening or thrilling, these glands pump adrenaline into your bloodstream within seconds. The chemical makes your heart pound faster, your breathing quicken, and your muscles tense up, ready for action. Blood rushes to your arms and legs so you can run faster or fight harder. You might feel a burst of energy, notice sounds more clearly, or even temporarily forget about pain.

This response helped our ancestors survive encounters with predators and other dangers. Today, you might feel an adrenaline rush before giving a speech, during a close basketball game, or on a roller coaster. Some people seek out adrenaline by doing risky activities like skydiving or rock climbing.

The effect usually lasts only a few minutes. Afterward, you might feel shaky or tired as your body returns to normal. People sometimes call adrenaline by its scientific name, epinephrine, especially in medical settings, where doctors might use it as an emergency medication.