The adrenal glands sit atop the kidneys like a pair of small caps. Each has two distinct parts that produce different families of hormones and serve different emergency needs.

The outer cortex releases cortisol, which helps the body manage long-term stress, regulate blood sugar, and control inflammation, and aldosterone, which manages salt and water balance. The inner medulla releases adrenaline and noradrenaline—the classic fight-or-flight hormones—within seconds of a perceived threat. Heart rate rises, blood is redirected to muscles, pupils dilate, and digestion slows. The whole system is designed for rapid mobilization followed by a return to baseline once the danger passes.

Chronic activation of the stress response, however, exacts a cost. Prolonged high cortisol is linked to immune suppression, weight gain, and mood disruption. Disorders of the adrenal glands themselves—Cushing’s syndrome, Addison’s disease, pheochromocytoma—produce dramatic symptoms that underscore how central these small organs are to everyday physiological balance.

When someone says their adrenaline is pumping, they are describing the medulla at work. When they speak of burning out under pressure, the cortex is often part of the story.