1 of or pertaining to the adrenal glands or their secretions
2 near the kidneys n : either of a pair of complex endocrine glands situated near the kidney [syn: adrenal gland, suprarenal gland]
- An adrenal gland.
In mammals, the adrenal glands (also known as suprarenal glands) are the triangle-shaped endocrine glands that sit on top of 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.
Anatomy and functionAnatomically, the adrenal glands are located in the thoracic abdomen situated atop the kidneys, specifically on their anterosuperior aspect. They are also surrounded by the adipose capsule and the renal fascia. In humans, the adrenal glands are found at the level of the 12th thoracic vertebra and receive their blood supply from the adrenal arteries.
The adrenal gland is separated into two distinct structures, both of which receive regulatory input from the nervous system:
- As its name suggests, the adrenal medulla is the central core of the adrenal gland, surrounded by the adrenal cortex. The chromaffin cells of the medulla are the body's main source of the catecholamine hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). These water-soluble hormones, derived from the amino acid tyrosine, are part of the fight-or-flight response initiated by the sympathetic nervous system. The adrenal medulla can be considered specialized ganglia of the sympathetic nervous system, lacking distinct synapses, instead releasing secretions directly into the blood. It is also the main source of dopamine, a catecholamine closely related to adrenaline and noradrenaline.
- By contrast, the adrenal cortex is devoted to the synthesis of corticosteroid hormones from cholesterol. Some cells 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. In contrast to the direct innervation of the medulla, the cortex is regulated by neuroendocrine hormones secreted by the pituitary gland and hypothalamus, as well as by the renin-angiotensin system.
Arteries and veinsAlthough 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:
Venous drainage of the adrenal glands is achieved via the suprarenal veins:
The adrenal glands and the thyroid gland are the organs that have the greatest blood supply per gram of tissue. Up to 60 arterioles may enter each adrenal gland.
- - "Adrenal Gland"
- - "Posterior Abdominal Wall: The Retroperitoneal Fat and Suprarenal Glands"
- Adrenal Gland, from Colorado State University
adrenal in Arabic: غدة كظرية
adrenal in Bengali: অ্যাড্রিনাল গ্রন্থি
adrenal in Bosnian: Nadbubrežna žlijezda
adrenal in Bulgarian: Надбъбречна жлеза
adrenal in Catalan: Glàndula adrenal
adrenal in Czech: Nadledvina
adrenal in Danish: Binyre
adrenal in German: Nebenniere
adrenal in Dhivehi: އެޑްރީނަލް ގްލޭންޑް
adrenal in Spanish: Glándula suprarrenal
adrenal in Esperanto: Surrena glando
adrenal in French: Glande surrénale
adrenal in Croatian: Nadbubrežna žlijezda
adrenal in Indonesian: Kelenjar adrenal
adrenal in Interlingua (International Auxiliary Language Association): Glandula adrenal
adrenal in Italian: Surrene
adrenal in Hebrew: בלוטת יותרת הכליה
adrenal in Javanese: Kelenjar adrenal
adrenal in Latin: Glandula adrenalis
adrenal in Lithuanian: Antinkstis
adrenal in Hungarian: Mellékvese
adrenal in Macedonian: Надбубрежна жлезда
adrenal in Dutch: Bijnier
adrenal in Japanese: 副腎
adrenal in Norwegian: Binyre
adrenal in Polish: Nadnercze
adrenal in Portuguese: Glândula supra-renal
adrenal in Russian: Надпочечники
adrenal in Simple English: Adrenal gland
adrenal in Finnish: Lisämunuainen
adrenal in Swedish: Binjure
adrenal in Telugu: అధివృక్క గ్రంధి
adrenal in Thai: ต่อมหมวกไต