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In mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s, the adrenal glands (also known as suprarenal glands) are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position (ad-, "near" or "at" + renes, "kidneys"; and as concerns supra-, meaning "above"). They are chiefly responsible for regulating the stress
Stress (medicine)

Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or body threats to the organism, whether actual or imagined....
 response through the synthesis
Biosynthesis

Biosynthesis is a phenomenon wherein chemical compounds are produced from simpler reagents. Biosynthesis, unlike chemosynthesis, takes place within living organisms and is generally catalyst by enzymes....
 of corticosteroid
Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiology systems such as stress , immune system and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior....
s and catecholamine
Catecholamine

Catecholamines are chemical compounds derived from the amino acid tyrosine. Their name is derived from the fact that they contain catechol and amine moieties....
s, including cortisol
Cortisol

Cortisol is a corticosteroid hormone or glucocorticoid produced by the adrenal cortex, that is part of the adrenal gland . It is usually referred to as the "stress hormone" as it is involved in response to stress and anxiety, controlled by Corticotropin-releasing hormone....
 and adrenaline, respectively.
omically, the adrenal glands are located in the thoracic abdomen situated atop the kidney
Kidney

The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
s, specifically on their anterosuperior aspect.






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In mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s, the adrenal glands (also known as suprarenal glands) are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position (ad-, "near" or "at" + renes, "kidneys"; and as concerns supra-, meaning "above"). They are chiefly responsible for regulating the stress
Stress (medicine)

Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or body threats to the organism, whether actual or imagined....
 response through the synthesis
Biosynthesis

Biosynthesis is a phenomenon wherein chemical compounds are produced from simpler reagents. Biosynthesis, unlike chemosynthesis, takes place within living organisms and is generally catalyst by enzymes....
 of corticosteroid
Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiology systems such as stress , immune system and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior....
s and catecholamine
Catecholamine

Catecholamines are chemical compounds derived from the amino acid tyrosine. Their name is derived from the fact that they contain catechol and amine moieties....
s, including cortisol
Cortisol

Cortisol is a corticosteroid hormone or glucocorticoid produced by the adrenal cortex, that is part of the adrenal gland . It is usually referred to as the "stress hormone" as it is involved in response to stress and anxiety, controlled by Corticotropin-releasing hormone....
 and adrenaline, respectively.

Anatomy and function

Anatomically, the adrenal glands are located in the thoracic abdomen situated atop the kidney
Kidney

The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
s, specifically on their anterosuperior aspect. They are also surrounded by the adipose capsule and the renal fascia
Renal fascia

The kidney and the adipose capsule are enclosed in a sheath of fibrous tissue continuous with the subperitoneal fascia, and named 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
Adrenal artery

The adrenal arteries are arteries in the human abdomen that supply blood to the adrenal glands.References ...
.

The adrenal gland is separated into two distinct structures, both of which receive regulatory input from the nervous system
Nervous system

The nervous system is a Neural network of specialized cells that communicate information about an animal's surroundings and itself. It processes this information and causes reactions in other parts of the body....
:

Adrenal medulla

The adrenal medulla
Adrenal medulla

The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex.Basic...
 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
Catecholamine

Catecholamines are chemical compounds derived from the amino acid tyrosine. Their name is derived from the fact that they contain catechol and amine moieties....
 hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). These water-soluble hormones, derived from the amino acid tyrosine
Tyrosine

Tyrosine or 4-hydroxyphenylalanine, is one of the 20 amino acids that are used by cell to protein biosynthesis proteins. This is a non-essential amino acid and it is found in casein....
, are part of the fight-or-flight response
Fight-or-flight response

'The 'fight-or-flight response', also called the fright, fight or flight response', 'hyperarousal' or the 'acute stress response', was first described by Walter Cannon in 1915....
 initiated by the sympathetic nervous system
Sympathetic nervous system

The Sympathetic Nervous System is a branch of the autonomic nervous system along with the enteric nervous system and parasympathetic nervous system....
. The adrenal medulla can be considered specialized ganglia of the sympathetic nervous system
Sympathetic nervous system

The Sympathetic Nervous System is a branch of the autonomic nervous system along with the enteric nervous system and parasympathetic nervous system....
, lacking distinct synapses, instead releasing secretions directly into the blood. It is also the main source of dopamine
Dopamine

Dopamine is a neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In the human brain, this phenethylamine functions as a neurotransmitter, activating the five types of dopamine receptors ? D1, D2, D3, D4 and D5, and their variants....
, a catecholamine
Catecholamine

Catecholamines are chemical compounds derived from the amino acid tyrosine. Their name is derived from the fact that they contain catechol and amine moieties....
 closely related to adrenaline and noradrenaline.

Adrenal cortex

The adrenal cortex
Adrenal cortex

Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively....
 is devoted to the synthesis of corticosteroid
Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiology systems such as stress , immune system and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior....
 hormones from cholesterol
Cholesterol

Cholesterol is a lipidic, waxy alcohol found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and membrane fluidity....
. Some cells belong to the hypothalamic-pituitary-adrenal axis
Hypothalamic-pituitary-adrenal axis

The hypothalamic-pituitary-adrenal axis , also known as thelimbic-hypothalamic-pituitary-adrenal axis , is a complex set of direct influences and feedback interactions among the hypothalamus , the pituitary gland , and the adrenal glands ....
 and are the source of cortisol
Cortisol

Cortisol is a corticosteroid hormone or glucocorticoid produced by the adrenal cortex, that is part of the adrenal gland . It is usually referred to as the "stress hormone" as it is involved in response to stress and anxiety, controlled by Corticotropin-releasing hormone....
 synthesis. Under normal unstressed conditions, the adrenal glands produce the equivalent of 35-40mg of cortisone acetate per day. Other cortical cells produce androgen
Androgen

Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors....
s such as testosterone
Testosterone

Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testis of males and the ovaries of females, although small amounts are also secreted by the adrenal glands....
, while some regulate water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 and electrolyte
Electrolyte

An electrolyte is any substance containing free ions that behaves as an electrical conductor medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions, but molten electrolytes and solid electrolytes are also possible....
 concentrations by secreting aldosterone
Aldosterone

Aldosterone is a hormone that increases the reabsorption of sodium and water and the release of potassium in the kidneys. This increases the volume of fluid in the body, and drives blood pressure up....
. In contrast to the direct innervation of the medulla, the cortex is regulated by neuroendocrine
Neuroendocrine

Neuroendocrine [IPA n??ro?'?nd?kr?n] cells are cells that release a hormone into the circulating blood in response to a neural stimulus. These hormones may be amines, neuropeptides, or specialized amino acids....
 hormones secreted by the pituitary gland
Pituitary gland

The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g . It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a Dura mater fold ....
 and hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
, as well as by the renin-angiotensin system
Renin-angiotensin system

The renin-angiotensin system or the renin-angiotensin-aldosterone system is a hormone system that regulates blood pressure and water balance....
.

The cortex is divided into three zona, or layers. This division is sometimes referred to as "Functional Zonation". Moving from the outermost layer in:

·The Zona Glomerulosa is the main site for production of Mineralocorticoids: namely Aldosterone, which plays an important role in the body's Na+ homeostasis. (regulated through the renin/angiotensinog II pathway) Sodium homeostasis is important not only for nerve function, but also blood osmolarity and pressure.

·The Zona Fasciculata is responsible for producing Glucocorticoids, Cortisol is its main secretion in humans, which influences carbohydrate metabolism. Cortisol secretion is stimulated by Adrenocorticotropic hormone, ACTH, from the anterior pituitary, by binding to a cell surface receptor and in turn increasing intracellular cAMP. It is important to note that cortisol secretion will remain at a basal level without ACTH stimulation.

·The Zona Reticularis acts a small production site for androgens, Dihydroepiandrosterone (DHEA) is the main secretion.

Arteries and veins

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 suprarenal artery
    Superior suprarenal artery

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

    The inferior phrenic arteries are two small vessels, which supply the diaphragm but present much variety in their origin.They may arise separately from the front of the aorta, immediately above the celiac artery, or by a common trunk, which may spring either from the aorta or from the celiac artery....
  • The middle suprarenal artery is provided by the abdominal aorta
    Abdominal aorta

    The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of descending aorta ....
  • The inferior suprarenal artery
    Inferior suprarenal artery

    Each renal artery gives off some small inferior suprarenal branches to the suprarenal gland, the ureter, and the surrounding cellular tissue and muscles....
     is provided by the renal artery
    Renal artery

    The renal arteries normally arise off the side of the abdominal aorta, immediately below the superior mesenteric artery, and supply the kidneys with blood....


Venous drainage of the adrenal glands is achieved via the suprarenal veins
Suprarenal veins

The Suprarenal veins are two in number:* the right ends in the inferior vena cava.* the left ends in the renal vein or left inferior phrenic vein....
:
  • The right suprarenal vein drains into the inferior vena cava
    Inferior vena cava

    The inferior vena cava is the large vein that carries de-oxygenated blood from the lower half of the body into the right atrium of the heart....
  • The left suprarenal vein drains into the left renal vein
    Renal vein

    The renal veins are veins that drain the kidney. They connect the kidney to the inferior vena cava.It is usually singular to each kidney, except in the condition "multiple renal veins"....
     or the left inferior phrenic vein
    Inferior phrenic vein

    The Inferior Phrenic Veins drain the diaphragm and follow the course of the inferior phrenic arteries;* the right ends in the inferior vena cava;...
    .


The suprarenal veins
Suprarenal veins

The Suprarenal veins are two in number:* the right ends in the inferior vena cava.* the left ends in the renal vein or left inferior phrenic vein....
 may form anastomoses with the inferior phrenic 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.

See also

  • Fight-or-flight response
    Fight-or-flight response

    'The 'fight-or-flight response', also called the fright, fight or flight response', 'hyperarousal' or the 'acute stress response', was first described by Walter Cannon in 1915....
  • Stress
    Stress (medicine)

    Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or body threats to the organism, whether actual or imagined....
  • Geoffrey Bourne


General references

- "Adrenal Gland"
  • , from Colorado State University