The Adrenal Cortex

The adrenal cortex is the biggest and outermost component of the adrenal gland. The zona glomerulosa, zona fasciculata, and zona reticularis are its three distinct zones. Each zone is in charge of manufacturing different hormones. This is also a secondary location for the production of androgens. 

The adrenal cortex is a dynamic organ with continual circular path cell migration under normal circumstances. Under these circumstances, the cortex quickly reacts to hormonal production demands by modifying the proportion of the areas in reaction to variations in a technique known as adrenal remodelling.

Functions of Adrenal Glands

Adrenal glands create hormones that are necessary for maintaining a healthy lifestyle. It generates hormones to regulate sex (androgenic hormones and estrogens), blood salt balance (aldosterone), and blood sugar balance (glucose). The adrenal medulla is responsible for producing hormones that aid in the fight-or-flight reflex. Hormones produced by the adrenal medulla and cortex are unique. Just on top of both kidneys, humans possess two adrenal glands. They are triangular and the same size and colour as fortune cookies. The cortex borders each gland’s medulla (the centre of the gland). 

Zones of the Adrenal Cortex

The neuroendocrine hormones released by the anterior pituitary and controlled by the hypothalamus modulate the adrenal cortex. The cortex is composed of three layers or zones:

• Zona Glomerulosa

The zona glomerulosa, the outermost layer, is the primary site for generating mineralocorticoids, primarily aldosterone, which is largely important for long-term blood pressure management. Aldosterone impacts the kidney’s distal convoluted tubule and collecting duct. This causes enhanced reabsorption of sodium and potassium (by primary cells) and the outflow of H+ ions. Angiotensin II is the primary trigger for aldosterone production, while ACTH[1] (adrenocorticotropic hormone) from the pituitary has only a short-term effect. These juxtaglomerular cells release angiotensin when the renal blood pressure falls under 90 mmHg.

• Zona Fasciculata

The layer between both the glomerulosa and reticular is known as the zona fasciculata. In people, this layer takes care of manufacturing glucocorticoids such as 11-deoxycorticosterone, corticosterone, and cortisol. Different hormones, such as glucagon and catecholamines, are stimulated by cortisol.

• Zona Reticularis

This is the lowest cortical layer. The zona reticularis generates androgens in people, primarily dehydroepiandrosterone (DHEA), DHEA sulphate (DHEA-S), and androstenedione (the precursor to testosterone).

Adrenal cortex hormones are hormones produced by the adrenal cortex. Different hormones are produced by the various districts of the adrenal cortex.

Mineralocorticoids

The zona glomerulosa is where mineralocorticoids are made. Aldosterone is by far the most important mineralocorticoid. The oligopeptide angiotensin II controls its production. Excessive extracellular potassium levels, lower extracellular sodium levels, and inadequate fluid and blood volume all cause aldosterone to be released. Aldosterone secretion has several effects on metabolism:

1. It enhances potassium ion outflow in the urine.
2. It raises sodium ion levels in the interstitial fluid.
3. It increases blood volume and water retention.

Glucocorticoids

The zona fasciculata is where glucocorticoids are made. Cortisol is the major glucocorticoid secreted by the adrenal gland in living beings. ACTH, a hormone produced by the anterior pituitary gland, controls its output. Cortisol boosts metabolism in a variety of ways after it binds to its goal:

1. It encourages the body to release amino acids.
2. It promotes lipolysis or fat decomposition.
3. It encourages the creation of sugars from recently released amino acids and lipids. This is a process known as gluconeogenesis.
4. It inhibits glucose uptake to muscle and fat cells, which raises blood sugar levels in response to stress.
5. It improves the strength of cardiac muscle contractions.
6. It aids in water retention.
7. It possesses anti-inflammatory and allergy-fighting properties.

Androgens

DHEA is by far the essential androgen produced by the zona reticularis. These hormones have no overall impact on a male body. In the gonads, they are transformed into much more potent androgens like testosterone and DHT, or even to estrogen (female sex hormones), functioning as a metabolic intermediary.

How to Remember the Adrenal Cortex Hormones

There are ways to remember the adrenal cortex hormones easily. Memorising ‘Salt, Sugar, Sex’ can help in recalling the functions of these three regions, as they correspond to the hormones generated for each layer of the adrenal cortex. Using the abbreviation ‘GFR’ for glomerulosa, fasciculata, and reticularis will also help you remember the names of such regions.

The glucocorticoid hormone-sensitising compounds, including corticosteroids, are found in the cytoplasm of cells in the adrenal cortex. Mineralocorticoids are adrenal hormones that primarily affect the transport of ions via epithelial cells, leading to potassium depletion and sodium retention. A deficiency of mineralocorticoids production may be a symptom of Addison’s disease (Addison’s illness). Glucocorticoids lower immunity to germs, viruses, and fungus, allowing disease to spread faster. In fatty tissue, they reduce lipogenesis and promote lipolysis. Wound dehiscence following surgery can be caused by high therapeutic dosages of adrenal corticosteroids or even the syndrome of hyperadrenocorticism.

Conclusion

The adrenal cortex is the biggest and outermost component of the adrenal gland. It has three distinct zones: the zona glomerulosa, zona fasciculata, and zona reticularis. All three of them have different functions and produce different hormones, regulating the hormone production in the human body. The abbreviation ‘GFR’ can used to remember the three zones in order, and ‘Salt, Sugar, Sex’ can be used to recall the functions of these regions.