In mammals, the adrenal glands (also known as suprarenal glands or colloquially as kidney hats) 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. Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... An endocrine gland is one of a set of internal organs involved in the secretion of hormones into the blood. ... Human kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Stress (roughly the opposite of relaxation) is a medical term for a wide range of strong external stimuli, both physiological and psychological, which can cause a physiological response called the general adaptation syndrome, first described in 1936 by Hans Selye in the journal Nature. ... Synthesis (from the Greek words syn = plus and thesis = position) is commonly understood to be an integration of two or more pre-existing elements which results in a new creation. ... In physiology, corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. ... Catecholamines are chemical compounds derived from the amino acid tyrosine that act as hormones or neurotransmitters. ... Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... Epinephrine (INN) or adrenaline (BAN) is a hormone and a neurotransmitter. ...

Overview

The adrenal glands are located in the abdomen and sit atop the kidneys.

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. Image File history File links Download high resolution version (683x900, 217 KB) File links The following pages link to this file: Adrenal gland Wikipedia:Grays Anatomy images with missing articles 23 ... Image File history File links Download high resolution version (683x900, 217 KB) File links The following pages link to this file: Adrenal gland Wikipedia:Grays Anatomy images with missing articles 23 ... Human kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... A typical thoracic vertebra The thoracic vertebrae (vertebrae thoracales) compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. ...

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 nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ...

The adrenal medulla is the body's main source of the catecholamine hormones epinephrine and 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. Epinephrine (INN) or adrenaline (BAN) is a hormone and a neurotransmitter. ... Norepinephrine or noradrenaline is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ... The hypothalamic-pituitary-adrenal axis (HPA axis) is a major part of the neuroendocrine system that controls reactions to stress and has important functions in regulating various body processes such as digestion, the immune system and energy usage. ... Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... 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. ... Testosterone is a steroid hormone from the androgen group. ... Water (from the Old English word wæter; c. ... An electrolyte is a substance that dissociates into free ions when dissolved (or molten), to produce an electrically conductive medium. ... Aldosterone is a steroid hormone synthesized from cholesterol by the enzyme aldosterone synthase. ...

Adrenal medulla

Composed mainly of hormone-producing chromaffin cells, the adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines epinephrine and norepinephrine (also called adrenaline and noradrenaline, respectively). Medullary cells are derived from the embryonic neural crest and, as such, are simply modified neurons. In particular, they are modified postganglionic cells of the sympathetic nervous system that have lost their axons and dendrites, receiving innervation from corresponding preganglionic fibers. Moreover, as the synapses between pre- and postganglionic fibers are called ganglia, the adrenal medulla is actually a ganglion of the sympathetic nervous system. Chromaffin cells are neuroendocrine cells found in the medulla of the adrenal gland and in other ganglia of the sympathetic nervous system. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in cheese), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. ... Epinephrine (INN) or adrenaline (BAN) is a hormone and a neurotransmitter. ... Norepinephrine or noradrenaline is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ... The neural crest, a component of the ectoderm, is one of several ridgelike clusters of cells found on either side of the neural tube in vertebrate embryos. ... Drawing by Santiago Ramón y Cajal of cells in the pigeon cerebellum. ... In vertebrate anatomy, a ganglion is a tissue mass that contains the dendrites and cell bodies (or somas) of nerve cells, in most case ones belonging to the peripheral nervous system. ... The sympathetic nervous system (SNS) is one half of the autonomic nervous system; the parasympathetic nervous system (PNS) is the other. ... An axon, or nerve fibre, is a long slender projection of a nerve cell, or neuron, which conducts electrical impulses away from the neurons cell body or soma. ... (The term dendrite may also refer to the metallurgical dendrite. ... In vertebrate anatomy, a ganglion is a tissue mass that contains the dendrites and cell bodies (or somas) of nerve cells, in most case ones belonging to the peripheral nervous system. ... Sympathetic nervous system innervation, showing the sympathetic chain ganglia An autonomic ganglion is a collection of neuron cell bodies within the autonomic nervous system. ...

In response to stressors such as exercise or imminent danger, medullary cells release catecholamines into the blood in a 70:30 ratio of epinephrine to norepinephrine. Notable effects of epinephrine and norepinephrine include increased heart rate, blood vessel constriction, bronchiole dilation, and increased metabolism, all of which are characteristic of the fight-or-flight response. A stressor is something that either speeds up a reaction rate or keeps the reaction rate the same. ... Marines exercising (attempting to do push-ups). ... Heart rate is a term used to describe the frequency of the cardiac cycle. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... The bronchioles are the first airway branches that no longer contain cartilage. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος (metabolismos), the Greek word for change, or overthrow (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. ... The flight or fight response, also called the acute stress response, was first described by Walter Cannon. ...

Adrenal cortex

Layers of the 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. It is also a secondary site of androgen synthesis. Image File history File links Adrenal_cortex_layers. ... Image File history File links Adrenal_cortex_layers. ... Mineralocorticoids is a class of steroids characterised by their similarity to aldosterone and their influence on salt and water metabolism. ... Glucocorticoids are a class of steroid hormones characterised by an ability to bind with the cortisol receptor and trigger similar effects. ... Aldosterone is a steroid hormone synthesized from cholesterol by the enzyme aldosterone synthase. ... Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... 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. ...

The cortex can be divided into three distinct layers of tissue based on their organization. The most superficial cortical layer is the zona glomerulosa, which produces mineralocorticoids (eg, aldosterone). Beneath the glomerulosa are the zonae fasciculata and reticularis, which produce glucocorticoids (eg, cortisol) and weak androgens (eg, dehydroepiandrosterone). Biological tissue is a substance made up of cells that perform a similar function. ... In mammals, the adrenal glands (also known as suprarenal glands or colloquially as kidney hats) 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... Mineralocorticoids is a class of steroids characterised by their similarity to aldosterone and their influence on salt and water metabolism. ... Aldosterone is a steroid hormone synthesized from cholesterol by the enzyme aldosterone synthase. ... The zona reticularis (inner region of the adrenal cortex) secretes and synthesize small amounts of weak androgens, steroids that have masculinizing effects. ... Glucocorticoids are a class of steroid hormones characterised by an ability to bind with the cortisol receptor and trigger similar effects. ... Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... 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. ... Dehydroepiandrosterone (DHEA) is a natural steroid hormone produced from cholesterol by the adrenal glands found atop of the kidneys in the human body. ...

All adrenocortical hormones are synthesised from cholesterol. Cholesterol is transported into the inner mitochondrial membrane by steroidogenic acute regulatory protein (StAR), where it is converted into pregnenolone by the enzyme CYP11A. Accordingly, production of hormones in all three layers of the adrenal cortex is limited by the transportation of cholesterol into the mitochondria and by its conversion into pregnenolone. Pregnenolone can be either dehydrogenated to progesterone or hydroxylated to 17-alpha-hydroxypregnenolone. The steps up to this point occur in many steroid-producing tissues. Subsequent steps, however, only occur in the adrenal cortex. Cholesterol chemical structure Cholesterol is a steroid, a lipid, and an alcohol, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... Pregnenolone is a steroid hormone involved in the steroidogenesis of progesterone, mineralocorticoids, glucocorticoids, androgens, and estrogens. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ...

• Progesterone ->(hydroxylation at C21)-> Deoxycorticosterone ->(two further hydroxylations)-> Aldosterone
• Progesterone -> (hydroxylation at C17)-> 17-alpha-hydroxyprogesterone ->(hydroxylation)-> Deoxycortisol ->(hydroxylation)-> Cortisol

Zona glomerulosa

The zona glomerulosa is the most superficial layer of the adrenal cortex, lying directly beneath the adrenal gland's capsule. Its cells are arranged in spherical clusters (glomus is Latin for "ball"). Latin was the language originally spoken in the region around Rome called Latium. ...

In response to increased potassium levels or decreased blood flow to the kidneys, cells of the zona glomerulosa secrete the mineralocorticoid aldosterone into the blood as part of the renin-angiotensin system. Aldosterone regulates the body's concentration of electrolytes, primarily sodium and potassium, by acting on the distal convoluted tubule of kidney nephrons to: General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... Aldosterone is a steroid hormone synthesized from cholesterol by the enzyme aldosterone synthase. ... The renin-angiotensin system (RAAS) or the renin-angiotensin-aldosterone system is a hormone system that helps regulate long-term blood pressure and blood volume in the body. ... An electrolyte is a substance that dissociates into free ions when dissolved (or molten), to produce an electrically conductive medium. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... Kidney nephron The distal convoluted tubule (DCT) is a portion of kidney nephron between the loop of Henle and the collecting duct system. ... Nephron of the kidney A nephron is the basic structural and functional unit of the kidney. ...

• increase sodium reabsorption
• increase potassium excretion
• increase water reabsorption through osmosis

Excretion is the biological process by which an organism chemically separates waste products from its body. ... Osmosis is the diffusion of a solvent through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration. ...

Zona fasciculata

Cells of the zona fasciculata sit directly beneath the zona glomerulosa and are organized in bundles (or fascicles). The zona chiefly produces glucocorticoids (eg, cortisol) and a small amount of weak androgens (eg, dehydroepiandrosterone). Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... 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. ... Dehydroepiandrosterone (DHEA) is a natural steroid hormone produced from cholesterol by the adrenal glands found atop of the kidneys in the human body. ...

Cortical cells responsible for the production of glucocorticoids are the primary effectors of adrenocorticotropic hormone (ACTH). The hypothalamus secretes corticotropin-releasing hormone which stimulates the anterior pituitary gland to release ACTH; another hypothalamic hormone, arginine vasopressin augments ACTH secretion, with the two together stimulating larger release than ACTH in isolation. ACTH acts on the adrenal cortex to stimulate the release of glucocorticoids. This three-organ endocrine system is commonly called the hypothalamic-pituitary-adrenal axis. Adrenocorticotropic hormone (ACTH or corticotropin) is a polypeptide hormone synthesised (from POMC, pre-opiomelanocortin) and secreted from corticotropes in the anterior lobe of the pituitary gland in response to the hormone corticotropin-releasing factor (CRF) released by the hypothalamus. ... In the anatomy of mammals, the hypothalamus is a region of the brain located below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate certain metabolic processes and other autonomic activities. ... Corticotropin-releasing hormone (CRH), also called corticotropin-releasing factor (CRF) or corticoliberin, is a polypeptide hormone involved in the stress response. ... The anterior pituitary (also called the adenohypophysis) comprises the anterior lobe of the pituitary gland and is part of the endocrine system. ... Antidiuretic hormone (ADH), or arginine vasopressin (AVP), is a peptide hormone produced by the hypothalamus, and stored in the posterior part of the pituitary gland. ... The hypothalamic-pituitary-adrenal axis (HPA axis) is a major part of the neuroendocrine system that controls reactions to stress. ...

The primary glucocorticoid released by the adrenal gland is cortisol. Upon binding to its target, cortisol enhances metabolism in several ways: Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος (metabolismos), the Greek word for change, or overthrow (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. ...

• stimulating the release of amino acids from the body
• stimulating lipolysis, the breakdown of fat
• stimulating gluconeogenesis, the production of glucose from newly-released amino acids and lipids
• conserving glucose by inhibiting uptake into muscle and fat cells

In addition to glucocorticoid production, the fasciculata is a secondary source of androgens such as testosterone, dihydrotestosterone (DHT), androstenedione, and dehydroepiandrosterone (DHEA). These enhance muscle mass, stimulate cell growth, and aid in the development of the secondary sex characteristics. In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Lipolysis is the breakdown of fat stored in fat cells. ... This article is about lipid molecules. ... Gluconeogenesis, ultimately, is the generation of glucose from noncarbohydrate sources like lactate, glycerol, and amino acids. ... Glucose (Glc), a monosaccharide, is one of the most important carbohydrates. ... Figure 1: Structure of a Lipid. ... Adipose tissue is an anatomical term for loose connective tissue composed of adipocytes. ... Testosterone is a steroid hormone from the androgen group. ... Dihydrotestosterone (DHT) is a biologically active metabolite of the hormone testosterone, formed primarily in the prostate gland, testes, hair follicles, and adrenal glands by the enzyme 5α-reductase by means of reducing the Δ4,5 double-bond. ... Androstenedione is a 19-carbon steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemical pathway that produces the androgen testosterone and the estrogens estrone and estradiol. ... Dehydroepiandrosterone (DHEA) is a natural steroid hormone produced from cholesterol by the adrenal glands found atop of the kidneys in the human body. ... A top-down view of skeletal muscle Muscle is a contractile form of tissue. ... The term cell growth is used in two different ways in biology. ... A peafowl displays its secondary sexual characteristics (long, colored feathers). ...

Zona reticularis

The innermost layer of the adrenal cortex, the zona reticularis sits beneath the zona fasciculata and atop the adrenal medulla. Its cells are arranged in a network of cords (a reticulum) and have the same functions as cells of the zona fasciculata. It is thought that the zona reticularis is the principal source of glucocorticoids and adrenal androgens, with the zona fasciculata activating only after prolonged stimulation.

Pathology

Adrenal cortex:

• Hypoadrenalism (e.g. due to Addison's disease)
• Cushing's syndrome
• Congenital adrenal hyperplasia
• Conn's syndrome

Adrenal medulla: Addisons disease (also known as chronic adrenal insufficiency, or hypocortisolism) is a rare endocrine disorder, first described by British physician Thomas Addison. ... Congenital adrenal hyperplasia (CAH) refers to any of several autosomal recessive diseases resulting from defects in steps of the synthesis of cortisol from cholesterol by the adrenal glands. ... Conns syndrome is overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands. ...

• Pheochromocytoma is a catecholamine-secreting tumor of the adrenal medulla.

A pheochromocytoma (also phaeochromocytoma, English spelling) is a tumor in the medulla of the adrenal glands (or, rarely, the ganglia of the sympathetic nervous system) which secretes excessive amounts of catecholamines, usually epinephrine and norepinephrine. ... Catecholamines are chemical compounds derived from the amino acid tyrosine that act as hormones or neurotransmitters. ...

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. Under surface of the human diaphragm. ... The largest artery in the human body, the aorta originates from the left ventricle of the heart and brings oxygenated blood to all parts of the body in the systemic circulation. ...

The middle suprarenal artery is a branch directly off the aorta, while the inferior suprarenal artery branches from the aorta or the renal artery. Human kidneys viewed from behind with spine removed The renal arteries normally arise off the abdominal aorta and supply the kidneys with blood. ...

See also

• Fight-or-flight response
• Stress

The flight or fight response, also called the acute stress response, was first described by Walter Cannon. ... Stress (roughly the opposite of relaxation) is a medical term for a wide range of strong external stimuli, both physiological and psychological, which can cause a physiological response called the general adaptation syndrome, first described in 1936 by Hans Selye in the journal Nature. ...

References

• Adrenal Gland, from Colorado State University
• MedlinePlus Medical Encyclopedia: Adrenal Glands