Adrenal Cortex: Structure, Hormones and Disorders

The adrenal cortex is the outer and largest part of the adrenal gland. It is associated with the production of hormones that are essential for life. Inside the cortex lies the adrenal medulla, which also produces hormones.

Layers of Adrenal Cortex

• It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis.
• Zona glomerulosa: It is the outermost layer of the adrenal cortex that serves as a site for the synthesis of mineralocorticoids, chiefly aldosterone. It is responsible for the regulation of blood pressure in the long term.
• Zona fasciculata: It is the middle layer situated between glomerulosa and reticularis. It is responsible for the synthesis of glucocorticoids, such as cortisol and corticosterone.
• Zona reticularis: It is the innermost cortical layer of the adrenal gland. It is mainly responsible for the production of androgens.

Hormones of Adrenal Cortex

Different layers of the adrenal cortex produce different hormones and perform different functions. The hormones produced by the adrenal cortex are:

1. Mineralocorticoids: It is a family of hormones produced in the zona glomerulosa. The chief hormone produced is aldosterone. It is mainly responsible for the regulation of blood pressure. It is also responsible for the regulation of distal convoluted tubules and collecting duct, which leads to higher absorption of sodium ions and higher excretion of potassium and hydrogen ions.
2. Glucocorticoids: It is produced in the zona fasciculata. The primary glucocorticoid produced by the adrenal cortex is cortisol. It regulates metabolism by stimulating the breakdown of fat (lipolysis), the release of amino acids from the body, and also helps in gluconeogenesis: production of new glucose.
3. Androgens: Androgens are produced in the innermost layer of zona reticularis. The chief hormones it produces are:

• Testosterone: It is the primary sex hormone in males that are responsible for developing secondary sex characteristics.
• Dihydrotestosterone: It is a more potent form of testosterone that binds readily to the androgen receptors.
• Androstenedione: It is a weaker steroid androgen that acts as a precursor for the synthesis of estrone and testosterone.
• Dehydroepiandrosterone (DHEA): It is an endogenous steroid circulating most abundantly in the human circulatory system. It is a precursor in the production of sex hormones in both males and females.

Disorders of the Adrenal Cortex

1. Addison’s Disease: Also called adrenal insufficiency, this condition is characterised by low secretion of cortisol and aldosterone which causes nausea, fatigue, dizziness and low blood pressure.
2. Cushing’s Syndrome: This condition is developed when the body produces too much cortisol or overconsumption of steroidal drugs. It is shown by symptoms such as fatty hump between shoulders, rounded face, and pink or purple stretch marks.
3. Congenital Adrenal Hyperplasia: It is a group of inherited adrenal disorders where the adrenal glands cannot produce enough hormones but overproduction of aldosterone. This leads to inappropriate development of genitalia in both males and females.
4. Adrenal Gland Suppression: Due to the consumption of steroidal drugs the activity of adrenal glands gets suppressed and the hormones are not produced. It is always advised to consume steroids after consulting an expert.
5. Hyperaldosteronism: In this condition, excess aldosterone is produced which elevates blood pressure and increase potassium loss.
6. Virilization: It is a condition often seen in females because they develop secondary male characteristics due to the overproduction of androgens.

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Also Read:

• What Is the Main Function of the Adrenal Cortex?
• What Is Androgen Hormone in Females?
• What Stimulates Androgen Production?