Adrenal Cortex: Structure,Hormones and Disorders MCQ - Practice Questions with Answers

• Adrenal Glands are paired structures located on the top of the kidneys. 
• Each adrenal gland has two parts:
  • exter­nal adrenal cortex 
  • internal ad­renal medulla
• The cortex is sur­rounded by a fibrous capsule.

Adrenal Cortex:

• The adrenal cortex is derived from the mesoderm of the embryo.
• It is subdivided into three zones:
  • Zona glomerulosa: This is the outer zone that lies just below the capsule. It constitutes about 15% of the gland. Mineralocorticoids are secreted from this region. 
  • Zona fasciculata: This is the middle zone which is widest of the three zones. It constitutes about 50% of the gland. Glucocorticoids are secreted from this region.
  • Zona reticularis: This is the inner zone that constitutes about 7% of the gland. Gonadocorticoids are secreted from this region. 

Hormones of the Adrenal Cortex:

• Mineralocorticoids:
  • They are responsible for the regulation of mineral metabolism. 
  • Aldosterone (salt-retaining hormone) is the principal mineralocorticoid (90 to 95%) in humans.
  • It is secreted when the sodium level is low.
  • It acts on the kidneys to cause more sodium to be returned to the blood and more potassium to be excreted. 
  • As the sodium concentration in the blood increases, water follows it by osmosis, so the blood volume also increases. 
  • Thus the effect of aldosterone is to increase both sodium and water in the blood.
• Glucocorticoids:
  • They affect carbohydrate metabolism, however, they also affect the metabolism of proteins and fats.
  • Glucocorticoids include three main hormones: cortisol (= hydrocortisone), corticosterone and cortisone.
  • Cortisol is the most abundant (about 95%). 
  • It stimulates the liver to synthesize carbohydrates from non-carbohydrates such as amino acids and glycerol.
  • The third effect of cortisol is to stimulate the break-down of fats in adipose tissue and release fatty acids into the blood.
  • It retards phagocytic activities of WBCs and thus suppresses ‘inflammation reaction’.
  • Cortisol is also “immunosuppressive”. 
  • It suppresses the synthesis of antibodies by inhibiting the production of lymphocytes in lymphoid tissues.
  • Cortisol has the capacity to cope with stress.
• Gonadocorticoids:
  • They are also called sex hormones of adrenal glands. 
  • Large quantities of male than female sex-corticoids (sex hormones) are produced. 
  • These male sex hormones are called androgens which are important in the development of a male foetus.
    

(i) Addison’s disease:

• It is caused by the deficiency of mineralocorticoids and glucocorticoids.
• It is also caused by the destruction of the adrenal cortex in diseases such as tuberculosis.
• Its symptoms include low blood sugar, low plasma Na+, high K+ plasma, increased urinary Na+, nausea, vomiting, diarrhoea and a bronze-like pigmentation of the skin.
• Severe dehydration is also common in the person suffering from this disease.

(ii) Cushing’s Syndrome:

• It is caused by an excess of cortisol which may be due to a tumour of the adrenal cortex.
• It is characterised by high blood sugar, the appearance of sugar in the urine, rise in plasma Na+, fall in plasma K+, rise in blood volume, high blood pressure, obesity and wasting of muscles of thighs and pectoral and pelvic girdles.

(iii) Aldosteronism (Conn’s Syndrome):

• Excessive production of aldosterone from an adrenal cortical tumour causes this disease. 
• Its symptoms include a high plasma Na+, low plasma K+, rise in blood volume, high blood pressure and polyurea.

(iv) Adrenal Virilism:

• The appearance of male characters in the female is called virilism. 
• Excessive production of male sex-corticoids (androgens) produces male secondary sexual characters like beard, moustache, hoarse voice in the woman.

(v) Gynaecomastia:

• It is the development of enlarged mammary glands (breasts) in males. 
• It is due to excessive secretion of female sex hormones (oestrogens) in males.
• Decreased testosterone may also lead to gynecomastia.