The two adrenal glands are small and triangular, with one located atop of each kidney. For this reason, they have been called the suprarenal glands. Each adrenal gland has an outer region (called the adrenal cortex) and an inner region (called the adrenal medulla). The adrenal glands coordinate with the hypothalamus and pituitary gland in the brain to secrete hormones that regulate metabolism, blood chemistry, and many physical characteristics. Adrenal glands also secrete hormones during significant physical or emotional stress.
Hormones secreted by the adrenal glands include:
From the adrenal cortex:
Corticosteroid hormones (hydrocortisone or cortisol). Help control the body's metabolism of fats, proteins, and carbohydrates, suppress inflammation, and sustain immune function.
Aldosterone. Maintains blood volume and blood pressure by inhibiting the amount of sodium excreted into the urine.
Androgenic steroids (androgen hormones). Affect the development of pubic and underarm hair, and production of adult body odor.
Hormones secreted by the adrenal glands also include:
From the adrenal medulla:
Epinephrine (adrenaline). Increases the heart rate and force of heart contractions, facilitates blood flow to the muscles and brain, relaxes smooth muscles in arteries, converts starch to simple sugar in the liver, and other activities.
Norepinephrine (noradrenaline). Increases blood pressure through strong vasoconstrictive effects (narrowing of the blood vessels).
Certain genetic adrenal gland disorders are characterized by an inability of the adrenal glands to produce cortisol (also known as hydrocortisone) and aldosterone starting before birth (congenital). Because of a missing enzyme (a substance that speeds up or performs essential chemical reactions), intermediate chemicals may be diverted within the adrenal gland to produce excessive androgens that masculinize affected females. Infants born in the United States are screened for the most common form of this congenital adrenal disorder.