Adrenal Cortex- Important Hormones And Deficiency Disorders

Hormones Secreted by the Adrenal Cortex are the following-

Mineralocorticoids:

These are the steroid hormones secreted by the outermost cellular layer (zona glomerulosa) of the adrenal cortex. The fundamental mineral corticosteroid is aldosterone. Its secretion occurs when there is a fall in plasma sodium concentration or rise in plasma potassium.

They control electrolyte and water balance by regulating sodium and potassium salts. Aldosterone minimizes the excretion of Na+ in the urine, sweat, saliva and bile by the active absorption of this ion from those fluids. It enhances the elimination of K+ in place of absorbed Na+. It also controls inflammation.

Glucocorticoids:

These are a group of hormones secreted from the middle cellular layer (Zona Fasciculata) of the adrenal cortex, on stimulation by ACTH from the anterior pituitary. The glucocorticoids exert a feedback inhibitory effect on corticotropin secretion. Cortisone, cortisol and corticosterone are the main glucocorticoids.

They regulate the metabolism of carbohydrates, fats and proteins. They have influences on cardiovascular, skeletal muscle, CNS, lymphoid, connective and other tissues. They suppress inflammation and help to cope up with stress.

Sex Corticoids:

They are steroid hormones produced by zona fasciculata and zona reticularis. These hormones are androgens (androstenedione, dehydroepiandrosterone, testosterone) and oestrogen.

Androgens are male hormones required for development and maintenance of external/secondary sexual characters in males like body and facial hairs formation, deepening of the voice.

Oestrogen is a female hormone which plays a role in the development and maintenance of female secondary sexual characters like enlargement of breasts, the onset of the menstruation cycle.

The adrenal cortex is stimulated to secrete its hormone by ACTH from the anterior lobe of the pituitary gland. There is the presence of accessory cortical tissue in man in very small amounts, formed in retroperitoneal tissue, kidney, liver and gonads.

Disorders of the Adrenal Cortex:

Improper functioning of adrenal cortex produces the following disorders-

Addison’s Disease:

This disease is caused by the deficiency of mineralocorticoids and glucocorticoids. It is characterized by bronze-like skin colouration, hyponatraemia, hyperkalemia, excretion of Na+ and water in urine (dehydration), nervous depression, nausea, vomiting, weakness, fatigue, low blood pressure and diarrhoea.

Cushing’s Syndrome:

Over secretion of cortisol (glucocorticoids) causes Cushing’s syndrome which is characterized by high sugar level in the blood (hyperglycemia), loss of sugar in the urine (glycosuria), loss of weight as large number of amino acids changed into sugars, high Na+/low K+ concentration in the plasma, rise in blood volume and blood pressure and swollen face, neck, hands etc. due to deposition of fats below the skin of these body parts (i.e. obesity).

Aldosteronism (Conn’s Syndrome):

It is caused due to oversecretion of aldosterone due to adrenal cortical tumour. It is characterized by a rise in blood volume, blood pressure but without oedema, muscular weakness, high plasma Na+ due to decreased renal excretion, resulting in kidney damage and polyuria, low Ca++ level, i.e. muscular tetani.

Adrenal Virillism:

Oversecretion of sex corticoids in female causes Adrenal virilism or pseudohermaphroditism in which male-type secondary characters like facial hair (called hirsutism) hoarse voice, heavy arms and legs, receding hairline etc. appear in the female while it causes gynecomastia (enlarged breasts) in males.

No Comments

Add a Comment

Your email address will not be published. Required fields are marked *