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Adrenal cortex
 
 
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Situated along the perimeter of the adrenal gland
Adrenal gland

In mammals, the adrenal glands are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position . They are chiefly responsible for regulating the stress response through the biosynthesis of corticosteroids and catecholamines, including cortisol and adrenaline, respectively....
, the adrenal cortex mediates the stress response through the production of mineralocorticoid
Mineralocorticoid

Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt balance and water balance ....
s and glucocorticoid
Glucocorticoid

Glucocorticoids are a class of steroid hormones which bind to the glucocorticoid receptor , which is present in almost every animal cell.GCs are part of the feedback mechanism in the immune system which turns immune activity down....
s, including 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....
 and 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....
 respectively. It is also a secondary site of 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....
 synthesis.

cortex can be divided into three distinct layers of tissue
Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function....
 based on their organisation.



adrenocortical hormones are synthesised 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....
.






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Situated along the perimeter of the adrenal gland
Adrenal gland

In mammals, the adrenal glands are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position . They are chiefly responsible for regulating the stress response through the biosynthesis of corticosteroids and catecholamines, including cortisol and adrenaline, respectively....
, the adrenal cortex mediates the stress response through the production of mineralocorticoid
Mineralocorticoid

Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt balance and water balance ....
s and glucocorticoid
Glucocorticoid

Glucocorticoids are a class of steroid hormones which bind to the glucocorticoid receptor , which is present in almost every animal cell.GCs are part of the feedback mechanism in the immune system which turns immune activity down....
s, including 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....
 and 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....
 respectively. It is also a secondary site of 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....
 synthesis.

Layers

The cortex can be divided into three distinct layers of tissue
Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function....
 based on their organisation.

Layer Name Primary product >- | Most superficial cortical layer zona glomerulosa
Zona glomerulosa

The zona glomerulosa of the adrenal gland is the most superficial layer of the adrenal cortex, lying directly beneath the adrenal gland's capsule....
 		 mineralocorticoid
Mineralocorticoid

Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt balance and water balance ....
s (eg, 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....
) |- | Middle cortical layer 		zona fasciculata
Zona fasciculata

Cells of the zona fasciculata sit directly beneath the zona glomerulosa and are organized in bundles .The zona chiefly produces glucocorticoids and a small amount of weak androgens .Adrenal tumour of the zona fasciculata may lead to primary adrenocortical hypersecretion....
  		glucocorticoid
Glucocorticoid

Glucocorticoids are a class of steroid hormones which bind to the glucocorticoid receptor , which is present in almost every animal cell.GCs are part of the feedback mechanism in the immune system which turns immune activity down....
s (eg, 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....
) |- | Deepest cortical layer 		zona reticularis
Zona reticularis

The zona reticularis is the innermost layer of the adrenal cortex, lying deep to the zona fasciculata and superficial to the adrenal medulla. The cells are arranged cords that project in different directions giving a net-like appearance ....
 		 weak 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 (eg, dehydroepiandrosterone
Dehydroepiandrosterone

Dehydroepiandrosterone is a multi-functional steroid that has been implicated in a broad range of biological effects in humans and other mammals....
)


Hormone synthesis

All adrenocortical hormones are synthesised 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....
. 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....
 is transported into the inner mitochondrial membrane
Inner mitochondrial membrane

The mitochondrial inner membrane forms internal compartments known as cristae, which allow greater space for the proteins such as cytochromes to function properly and efficiently....
 by steroidogenic acute regulatory protein
Steroidogenic acute regulatory protein

The steroidogenic acute regulatory protein, commonly referred to as StAR , is a transport protein that regulates cholesterol transfer within the mitochondria, which is the rate-limiting step in the production of steroid hormones....
 , where it is converted into pregnenolone
Pregnenolone

Pregnenolone is a steroid hormone involved in the steroidogenesis of progesterone, mineralocorticoids, glucocorticoids, androgens, and estrogens....
 by the enzyme . 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
Progesterone

Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen....
, or hydroxylated to 17-alpha-hydroxypregnenolone.

The steps up to this point occur in many steroid
Steroid

A steroid is a terpenoid lipid characterized by a carbon skeleton with four fused rings, generally arranged in a 6-6-6-5 fashion.Steroids vary by the functional groups attached to these rings and the oxidation state of the rings....
-producing tissues. Subsequent steps, however, only occur in the adrenal cortex:
  • Progesterone ? (hydroxylation at C21) ? 11-Deoxycorticosterone
    Deoxycorticosterone

    Deoxycorticosterone is a steroid hormone produced by the adrenal gland that possess mineralocorticoid activity and acts as a Precursor to aldosterone....
     ? (two further hydroxylations at C11 and C18) ? 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....
  • Progesterone ? (hydroxylation at C17) ? 17-alpha-hydroxyprogesterone ? (hydroxylation at C21) ? 11-Deoxycortisol
    11-Deoxycortisol

    11-Deoxycortisol is a steroid, and an immediate precursor to the production of cortisol. It can be synthesized from 17-hydroxyprogesterone....
     ? (hydroxylation at C11) ? 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....


Production

The adrenal cortex produces a number of different 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....
 hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s.

Mineralocorticoids

They are produced in the zona glomerulosa
Zona glomerulosa

The zona glomerulosa of the adrenal gland is the most superficial layer of the adrenal cortex, lying directly beneath the adrenal gland's capsule....
. The primary mineralocorticoid
Mineralocorticoid

Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt balance and water balance ....
 is 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....
. Its secretion is regulated by the oligopeptide
Oligopeptide

An oligopeptide consists of between two and twelve amino acids. Oligopeptides Categories:Amanitins - Cyclic peptides taken from carpophores of several different mushroom species....
 angiotensin II (angiotensin II is regulated by angiotensin I, which in turn is regulated by renin
Renin

Renin , also known as Angiotensinogenase, is a circulating enzyme that participates in the body's renin-angiotensin system that mediates extracellular volume , and arterial vasoconstriction....
). Aldosterone is secreted in response to high extracellular
Extracellular

In cell biology, molecular biology and related fields, the word extracellular means "outside the cell ". This space is usually taken to be outside the plasma membranes, and occupied by fluid....
 potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
 levels, low extracellular sodium
Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
 levels, and low fluid levels and blood volume. Aldosterone affects metabolism
Metabolism

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
 in different ways:
  • It increases urinary
    Urine

    Urine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra....
     excretion of potassium ions
  • It increases interstitial levels of sodium ions
  • It increases water retention and blood volume


Glucocorticoids

They are produced in the zona fasciculata
Zona fasciculata

Cells of the zona fasciculata sit directly beneath the zona glomerulosa and are organized in bundles .The zona chiefly produces glucocorticoids and a small amount of weak androgens .Adrenal tumour of the zona fasciculata may lead to primary adrenocortical hypersecretion....
. The primary glucocorticoid released by the adrenal gland is 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....
. Its secretion is regulated by the hormone ACTH
Adrenocorticotropic hormone

Adrenocorticotropic hormone is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress ....
 from the anterior pituitary
Anterior pituitary

The anterior pituitary comprises the Anterior#Usage in human anatomy lobe of the pituitary gland and is part of the endocrine system. Unlike the posterior pituitary, the anterior lobe is genuinely glandular, hence the root adeno in its name....
. Upon binding to its target, cortisol enhances metabolism
Metabolism

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
 in several ways:
  • It stimulates the release of amino acid
    Amino acid

    In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
    s from the body
  • It stimulates lipolysis
    Lipolysis

    Lipolysis is the breakdown of fat stored in fat cells. During this process, free fatty acids are released into the bloodstream and circulate throughout the body....
    , the breakdown of fat
    Fat

    Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemistry, fats are generally ester of glycerol and fatty acids....
  • It stimulates gluconeogenesis
    Gluconeogenesis

    Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactic acid, glycerol, and glucogenic amino acids....
    , the production of glucose
    Glucose

    Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
     from newly-released amino acids and lipid
    Lipid

    Lipids are broadly defined as any fat-soluble , naturally-occurring molecule, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others....
    s
  • It increases blood glucose levels in response to stress, by inhibiting glucose uptake into muscle and fat cells
    Adipose tissue

    In histology, adipose tissue or fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and Thermal insulation the body....
  • It strengthens cardiac muscle
    Cardiac muscle

    Cardiac muscle is a type of involuntary sarcomere muscle found in the walls of the heart, specifically the wikt:myocardium. Cardiac muscle cells are known as cardiac myocytes ....
     contractions
  • It increases water retention
  • It has anti-inflammatory and anti-allergic effects


Androgens

They are produced in the zona reticularis
Zona reticularis

The zona reticularis is the innermost layer of the adrenal cortex, lying deep to the zona fasciculata and superficial to the adrenal medulla. The cells are arranged cords that project in different directions giving a net-like appearance ....
. The most important androgens include:
    • 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....
      : a hormone with a wide variety of effects, ranging from enhancing muscle mass and stimulation of cell growth
      Cell growth

      The term cell growth is used in the contexts of Cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"....
       to the development of the secondary sex characteristic
      Secondary sex characteristic

      Secondary sex characteristics are traits that distinguish the two sexes of a species, but that are not directly part of the reproductive system....
      s.
    • Dihydrotestosterone
      Dihydrotestosterone

      Dihydrotestosterone While DHT is best known for its roles in causing male pattern hair loss and prostate problems, it is crucial to virilization and is necessary to mitigate estrogen's effects in men....
       (DHT): a metabolite
      Metabolism

      Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
       of testosterone, and a more potent androgen than testosterone in that it binds more strongly to androgen receptors.
    • Androstenedione
      Androstenedione

      Androstenedione is a 19-carbon steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemistry pathway that produces the androgen testosterone and the estrogens estrone and estradiol....
       (Andro): an androgenic steroid produced by the testes, adrenal cortex, and ovaries. While androstenedione
      Androstenedione

      Androstenedione is a 19-carbon steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemistry pathway that produces the androgen testosterone and the estrogens estrone and estradiol....
      s are converted metabolically to testosterone and other 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, they are also the parent structure of estrone
      Estrone

      Estrone is an estrogenic hormone secreted by the ovary as well as adipose.Estrone is one of the three estrogens, which also include estriol and estradiol....
      .
    • Dehydroepiandrosterone
      Dehydroepiandrosterone

      Dehydroepiandrosterone is a multi-functional steroid that has been implicated in a broad range of biological effects in humans and other mammals....
       (DHEA): It is the primary precursor of natural estrogen
      Estrogen

      Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone....
      s. DHEA is also called dehydroisoandrosterone or dehydroandrosterone.


Pathology

  • Adrenal insufficiency
    Adrenal insufficiency

    Adrenal insufficiency is a condition in which the adrenal glands, located above the kidneys, do not produce adequate amounts of steroid hormones , primarily cortisol, but may also include impaired aldosterone production which regulates sodium, potassium and water retention....
     (e.g. due to Addison's disease
    Addison's disease

    Addison's disease is a rare endocrine disorder in which the adrenal gland doesn't produce enough steroid hormones . It may develop in children and adults, and may occur as the result many underlying causes....
    )
  • Cushing's syndrome
    Cushing's syndrome

    Cushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone ....
  • Congenital adrenal hyperplasia
    Congenital adrenal hyperplasia

    Congenital adrenal hyperplasia refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands ....
  • Conn's syndrome
    Conn's syndrome

    Primary aldosteronism, also known as primary hyperaldosteronism, is characterized by the overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands....


See also

  • Adrenal gland
    Adrenal gland

    In mammals, the adrenal glands are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position . They are chiefly responsible for regulating the stress response through the biosynthesis of corticosteroids and catecholamines, including cortisol and adrenaline, respectively....


External links

- "Adrenal Gland"