Adrenal cortex

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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The adrenal cortex is the outer area of the hormone-producing adrenal gland. It has a three-layer structure and produces over 40 hormones. The most important are aldosterone, cortisol and the male sex hormones (androgens). Here you can read everything you need to know about the adrenal cortex: function, structure and important diseases!

What is the adrenal cortex?

The adrenal cortex is the outer part of the adrenal gland, built up in three layers. The inner area of the organ is called the adrenal medulla. The cortex makes up about four fifths of the total weight of the adrenal gland. The three layers of the adrenal cortex are:

Zona glomerulosa, the narrowest zone directly under the connective tissue capsule. Here the rounded, chromatin-rich cell nuclei are arranged in irregular round nests. They contain lipoid granules.
Zona fasciculata, the middle and broadest layer of the adrenal cortex. Here the cells are arranged in parallel strands that run perpendicular to the surface of the cortex.
Zona reticularis, in which the smaller, lipid-poor, pigment-rich cells are arranged in reticular strands.

The characteristics of the zones are dynamic and change over the course of life. The zona fasciculata dominates until puberty, after which the zona glomerulosa and the reticularis zone take up more space. The latter also shows signs of degeneration with advancing age.

What hormones does the adrenal cortex produce?

Different hormones are produced in each of the three layers of the adrenal cortex:

In the zona glomerulosa mineralocorticoids (especially aldosterone)
In the zona fasciculata glucocorticoids (especially cortisol)
In the reticular zone, androgens (mainly dehydroepiandrosterone and small amounts of testosterone and estrogen)

The release of these hormones is controlled by ACTH, a pituitary hormone.

The formation of these steroid hormones requires cholesterol, which comes from food or from the body's own endogenous synthesis and is absorbed by the adrenal cortex via a receptor.

What is the function of the individual hormones?

All hormones in the adrenal cortex perform vital functions in the body.

Mineral corticoids (such as adosterone)

Mineralocorticoids (especially aldosterone) from the zona glomerulosa, the outer area, are vital for the water and electrolyte balance. They influence and regulate blood pressure and blood vessel volume. The secretion of the mineralocorticoids is controlled by various hormones - above all by the so-called renin-angiotensin system, by serotonin and prostaglandin, but also by ACTH, a hormone of the pituitary gland (pituitary gland).

Glucocorticoids (especially cortisol)

Glucocorticoids such as cortisol from the zona fasciculata, the middle area of the adrenal cortex, are vital for the regulation of the carbohydrate, fat and protein metabolism. They promote the supply of glucose from amino acids (protein building blocks) in the liver, can inhibit the transport and utilization of glucose and thus increase the blood sugar level. The secretion of the glucocorticoids is controlled by ACTH.

When the organism comes under stress due to strenuous muscle work, major psychological excitement, infections, burns or major blood loss, the pituitary gland releases more ACTH. It causes the adrenal medulla to release the stress hormone adrenaline in an increased manner. The adrenal cortex in turn reacts to this with increased hormone production (the zona fasciculata enlarges).

Androgens

Androgens are produced in the zona reticularis, the innermost part of the adrenal cortex (and also in the testes). The most important representative is testosterone. Androgens influence the development of male sexual characteristics. Your distribution is also controlled by ACTH.

What problems can the adrenal cortex cause?

There are numerous diseases of the adrenal cortex:

Underactive (adrenal insufficiency) with a loss of aldosterone and cortisol production leads to an overproduction of ACTH (Addison's disease). Common symptoms are, for example, browning of the skin, tiredness, hunger for “salty food”, but otherwise a lack of appetite and weight loss, low blood pressure, indigestion, depression and irritability.

Enlargement of the adrenal gland or growths in this area lead to an overproduction of aldosterone, the Conn syndrome. It is characterized by high blood pressure that is difficult to control.

Cushing's syndrome is based on excessive glucocorticoid formation. Those affected show typical symptoms: trunk obesity, full moon face, muscle weakness and high blood pressure.

Adrenogenital syndrome (AGS) is caused by hyperplasia (enlargement) or (less often) by growths in the adrenal cortex. There is a premature development of male sexual characteristics in boys and masculinization (virilization) in girls. The cause of AGS is an enzyme defect that causes the adrenal cortex to produce too little aldosterone and cortisol and too much androgens.

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