Adrenal gland

Gray's Fig. 1183 – Suprarenal glands viewed from the front.

Gray's Fig. 1184 – Suprarenal glands viewed from behind.

In mammals, the adrenal glands (also known as suprarenal glands) are the triangle-shaped endocrine glands that sit atop the kidneys; their name indicates that position (ad, "near" or "at" + renes, "kidneys"). They are chiefly responsible for regulating the stress response through the synthesis of corticosteroids and catecholamines, including cortisol and adrenaline.

Overview

Above each human kidney is one of the two adrenal glands.

Anatomically, the adrenal glands are located in the abdomen, situated on the anteriosuperior aspect of the kidneys. In humans, the adrenal glands are found at the level of the 12th thoracic vertebra and receive their blood supply from the adrenal arteries.

It is separated into two distinct structures, the adrenal medulla and the adrenal cortex, both of which receive regulatory input from the nervous system. As its name suggests, the adrenal medulla is at the center of the adrenal gland surrounded by the adrenal cortex.

The adrenal medulla is the body's main source of the catecholamine hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). By contrast, some cells of the adrenal cortex belong to the hypothalamic-pituitary-adrenal axis and are the source of cortisol synthesis. Other cortical cells produce androgens such as testosterone, while some regulate water and electrolyte concentrations by secreting aldosterone.

Blood supply

Although variations of the blood supply to the adrenal glands (and indeed the kidneys themselves) are common, there are usually three arteries that supply each adrenal gland: the superior, middle and inferior suprarenal (or adrenal) arteries.

Each (left and right) superior suprarenal artery is a branch of the phrenic artery on that side of the body. The left and right phrenic arteries supply the diaphragm, and come off the aorta.

The middle suprarenal artery is a branch directly off the aorta, while the inferior suprarenal artery branches from the aorta or the renal artery.

See also

• Fight-or-flight response
• Stress

References

ISBN links support NWE through referral fees

• Adrenal Gland, from Colorado State University
• MedlinePlus Encylopedia 002219

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