What is "adrenal gland"

Capsule \Cap"sule\ (k[a^]p"s[=u]l), n. [L. capsula a little box or chest, fr. capsa chest, case, fr. capere to take, contain: cf. F. capsule.]

1. (Bot.) a dry fruit or pod which is made up of several parts or carpels, and opens to discharge the seeds, as, the capsule of the poppy, the flax, the lily, etc.

2. (Chem.)

   1. A small saucer of clay for roasting or melting samples of ores, etc.; a scorifier.

   2. a small, shallow, evaporating dish, usually of porcelain.

3. (Med.) A small cylindrical or spherical gelatinous envelope in which nauseous or acrid doses are inclosed to be swallowed.

4. (Anat.) A membranous sac containing fluid, or investing an organ or joint; as, the capsule of the lens of the eye. Also, a capsulelike organ.

5. A metallic seal or cover for closing a bottle.

6. A small cup or shell, as of metal, for a percussion cap, cartridge, etc.

   Atrabiliary capsule. See under Atrabiliary.

   Glisson's capsule, a membranous envelope, entering the liver along with the portal vessels and insheathing the latter in their course through the organ.

   Suprarenal capsule, a ductless gland secreting epinephrine, norepinephrine, and steroid hormones, on the upper end of each kidney. It is also called the adrenal gland, glandula suprarenalis, suprarenal gland, epinephros, atrabiliary capsule, and adrenal capsule. [1913 Webster +PJC] ||

n. (context anatomy English) In mammals, either of a pair of complex endocrine glands, situated above each kidney, secreting hormones which control the heart rate, blood pressure, and metabolism.

n. either of a pair of complex endocrine glands situated near the kidney [syn: adrenal, suprarenal gland]

The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which produces steroid hormones and an inner medulla. The adrenal cortex itself is divided into three zones: zona glomerulosa, the zona fasciculata and the zona reticularis.

The adrenal cortex produces three main types of steroid hormones: mineralocorticoids, glucocorticoids, and androgens. Mineralocorticoids (such as aldosterone) produced in the zona glomerulosa help in the regulation of blood pressure and electrolyte balance. The glucocorticoids cortisol and corticosterone are synthesized in the zona fasciculata; their functions include the regulation of metabolism and immune system suppression. The innermost layer of the cortex, the zona reticularis, produces androgens that are converted to fully functional sex hormones in the gonads and other target organs. The production of steroid hormones is called steroidogenesis, and involves a number of reactions and processes that take place in cortical cells. The medulla produces the catecholamines adrenaline and noradrenaline, which function to produce a rapid response throughout the body in stress situations.

A number of endocrine diseases involve dysfunctions of the adrenal gland. Overproduction of cortisol leads to Cushing's syndrome, whereas insufficient production is associated with Addison's disease. Congenital adrenal hyperplasia is a genetic disease produced by dysregulation of endocrine control mechanisms. A variety of tumors can arise from adrenal tissue and are commonly found in medical imaging when searching for other diseases.