· Adrenal glands are two in number, the Adrenal cortex and the Adrenal medulla.
· Each lies at the top of each kidney, hence also called the suprarenal glands.
2. Shape:
· They are roughly triangular or conical in shape.
· They are roughly triangular or conical in shape.
· The right gland is smaller than the left one.
· Each measure about 150×30-40×10mm.
· Each measure about 150×30-40×10mm.
3. Color: yellow
4. Weight: Average weight of each gland is about 5-9gm in adults.
5. Structure:
· Anatomically, each gland is composed of two distinct parts which are the cortex and the medulla.
· Anatomically, each gland is composed of two distinct parts which are the cortex and the medulla.
· These two parts are structurally, functionally and embryologically different from each other.
A. Adrenal cortex
· Adrenal cortex is mesodermal in origin. It constitutes 80-90% of the adrenal gland by volume.· It consists of three zones: Zona glomerulosa, Zona fasciculate, Zona reticularis.
(i) Zona glomerulosa
· The zona glomerulosa accounts for about 15 per cent of the volume of the adrenal cortex.
· It is a group of columnar cells with numerous mitochondria.
· It mainly secretes mineralocorticoids, a small number of glucocorticoids and sex hormones.
(ii) Zona fasciculate
· The zona fasciculata contributes about 78 per cent of cortical volume.
· The zona fasciculata contributes about 78 per cent of cortical volume.
· It is the widest layer (three-quarters of the volume of cortex) consists of large polyhedral cells containing spherical mitochondria and pigment granules upon which the brownish yellowish colour of cortex depends and has liposomes or lipid droplets.
· It secretes predominantly glucocorticoids and a small amount of sex hormones.
(iii) Zona reticularis
· This layer is made up of an irregular network of rows of cells lined by reticuloendothelial cells.
· This layer secretes sex hormones, a small amount of glucocorticoid but not aldosterone.
· The principal mineralocorticoid is aldosterone commonly called the 'salt retaining hormone'.
· Two basic functions of aldosterone are conservation of sodium and water and elimination of potassium.
· Aldosterone secretion occurs in response to a drop in blood Na+ content, blood volume or blood pressure or to a rise in blood K+ concentration.
· About 95 per cent of the mineralocorticoid activity is due to aldosterone.
· When stimulated by ACTH from the anterior pituitary, the zona fasciculata secretes primarily cortisol, also called hydrocortisone, along with smaller amounts of the related corticosterone.
· The principal mineralocorticoid is aldosterone commonly called the 'salt retaining hormone'.
· Two basic functions of aldosterone are conservation of sodium and water and elimination of potassium.
· Aldosterone secretion occurs in response to a drop in blood Na+ content, blood volume or blood pressure or to a rise in blood K+ concentration.
· About 95 per cent of the mineralocorticoid activity is due to aldosterone.
· When stimulated by ACTH from the anterior pituitary, the zona fasciculata secretes primarily cortisol, also called hydrocortisone, along with smaller amounts of the related corticosterone.
Functions of Adrenal Hormones
· Chemically adrenal hormones are steroidal in nature.
· Chemically adrenal hormones are steroidal in nature.
· Physiologically cortical hormone or cortisone or corticosteroids may be classified broadly as
1. Mineralocorticoids
2. Glucocorticoids
3. Sex hormones
1. Mineralocorticoids
2. Glucocorticoids
3. Sex hormones
1. Mineralocorticoids:
· The principal mineralocorticoid is aldosterone commonly called the 'salt retaining hormone'.
· Two basic functions of aldosterone are conservation of sodium and water and elimination of potassium.
· Aldosterone secretion occurs in response to a drop in blood Na+ content, blood volume or blood pressure or to a rise in blood K+ concentration.
· About 95 per cent of the mineralocorticoid activity is due to aldosterone.
· When stimulated by ACTH from the anterior pituitary, the zona fasciculata secretes primarily cortisol, also called hydrocortisone, along with smaller amounts of the related corticosterone.
· These are concerned with Na+, K+ and Cl + metabolism.
· They increase the reabsorption of sodium from urine, saliva, sweat and gastric juice whereas K+ is excreted from renal tubules causing potassium diuresis. Eg Aldosterone disorders of mineralocorticoids
· The principal mineralocorticoid is aldosterone commonly called the 'salt retaining hormone'.
· Two basic functions of aldosterone are conservation of sodium and water and elimination of potassium.
· Aldosterone secretion occurs in response to a drop in blood Na+ content, blood volume or blood pressure or to a rise in blood K+ concentration.
· About 95 per cent of the mineralocorticoid activity is due to aldosterone.
· When stimulated by ACTH from the anterior pituitary, the zona fasciculata secretes primarily cortisol, also called hydrocortisone, along with smaller amounts of the related corticosterone.
· These are concerned with Na+, K+ and Cl + metabolism.
· They increase the reabsorption of sodium from urine, saliva, sweat and gastric juice whereas K+ is excreted from renal tubules causing potassium diuresis. Eg Aldosterone disorders of mineralocorticoids
Hypofunction of mineralocorticoids:
· Its hypofunction causes Conn,s disease or aldosteronism.
· It is characterized by the Na+ and K+ imbalance, nervous disorder, convulsion (sudden shaking of the body) and death.
· Remedy: Administration of large doses of potassium or surgical operation.
· Its hypofunction causes Conn,s disease or aldosteronism.
· It is characterized by the Na+ and K+ imbalance, nervous disorder, convulsion (sudden shaking of the body) and death.
· Remedy: Administration of large doses of potassium or surgical operation.
Hyperfunction: Hypertension
2. Glucocorticoids:
· Glucocorticoids are a group of hormones that regulate carbohydrate, protein and lipid metabolism (opposite to that, of insulin).
· Glucocorticoids influence a wide variety of other vital functions, including inflammatory reactions and the capacity to cope with stress
· It causes hyperglycemia (raise blood sugar level) by involving in the gluconeogenesis in the liver or has an anti-anabolic function. It is an anti-leukaemic factor because it reduces the number of lymphocytes.
· It has anti-inflammatory properties (suppress the acute inflammatory reaction without forming antibody. It is anti-fibroblastic and anti-allergic and euphoria action (sense of well being and gain appetite, anti-stress.
Disorder of Glucocorticoids:
a. Hypersecretion: Its hypersecretion causes Cushing disease.
Symptoms:-
· Increase deposition of fat on the trunk only. Moon face, thick neck, thin buffalo hump which are tender and painful. High Na and K level, B.P. and excessive hair growth (hirsutism)
· Patient complains of fatigue and back pain.
a. Hypersecretion: Its hypersecretion causes Cushing disease.
Symptoms:-
· Increase deposition of fat on the trunk only. Moon face, thick neck, thin buffalo hump which are tender and painful. High Na and K level, B.P. and excessive hair growth (hirsutism)
· Patient complains of fatigue and back pain.
· Diabetes mellitus and poor wound healing.
· Osteoporosis, hypertension, hyperglycemia, retention of Na and diminution of K level.
· Osteoporosis, hypertension, hyperglycemia, retention of Na and diminution of K level.
b. Hyposecretion
· It is due to tuberculosis or adrenal cortex or insufficiency of cortisol and aldosterone.
· It is due to tuberculosis or adrenal cortex or insufficiency of cortisol and aldosterone.
· It causes Addison's disease.
· Clinical features:
· Muscular weakness, vomiting, gastrointestinal disturbance, low B.P., dark bronze colour pigmentation of the skin, susceptibility to various types of stress, renal failure, etc.
Remedy: Appropriate salt therapy
· Muscular weakness, vomiting, gastrointestinal disturbance, low B.P., dark bronze colour pigmentation of the skin, susceptibility to various types of stress, renal failure, etc.
Remedy: Appropriate salt therapy
3. Sex hormones:
· Adrenal cortex secretes both male and female sex hormones, (Gonadocorticoids) estrogens and androgens.
· Concentration of sex hormones secreted by normal adult adrenals is usually so low that their effects are insignificant.
· All hormones secreted by the adrenal cortex are steroids .derived from cholesterol.
· These are related to the proper functioning of sex organs and the development of secondary sex characters.
· Eg: Testosterone, Oestrogen etc.
Hyperfunction of Sex hormones:
· Its hypersecretion causes Adrenal virilism or Adrenogenital syndrome
· Due to excessive secretion of androgens, generally found in female sex but in male feminisation may occur but not common.
Symptoms:
· Reversal of sex characters in the main features of the female and changes into male.
· Face, body appearance, voice become male type, beard and moustache grow, menstruation stops, uterus, ovaries, breast degenerate and clitoris enlarges.
· Its hypersecretion causes Adrenal virilism or Adrenogenital syndrome
· Due to excessive secretion of androgens, generally found in female sex but in male feminisation may occur but not common.
Symptoms:
· Reversal of sex characters in the main features of the female and changes into male.
· Face, body appearance, voice become male type, beard and moustache grow, menstruation stops, uterus, ovaries, breast degenerate and clitoris enlarges.
B. Adrenal Medulla
· It is a part of the autonomic nervous system (sympathetic ganglion).· Its cells are large ovoid and are organized in cords and contain chromaffin granules which contain catecholamines (adrenaline and nor-adrenaline), besides ATP and opioid peptides.
· It is innervated by cholinergic preganglionic fibres from the splenic nerve.
· Catecholamine is formed by amino acids and phenylalanine.
· They have a short half-life (2 minutes).
· Hormones secreted by the Adrenal Medulla:
I. Epinephrine or Adrenaline:
· It is a powerful vasoconstrictor that raises B.P., heart rate, cardiac output.
I. Epinephrine or Adrenaline:
· It is a powerful vasoconstrictor that raises B.P., heart rate, cardiac output.
· It is used as a heart stimulant during emergency conditions so-called emergency hormone.
· At that time it enhances glycogenolysis quickly to produce a large amount of energy to face emergency conditions.
· It dilates the bronchi so it is used in the treatment of asthma.
· It also stimulates the secretion of TSH, ACTH etc.
· It dilates the bronchi so it is used in the treatment of asthma.
· It also stimulates the secretion of TSH, ACTH etc.
II. Norepinephrine or Nor-Adrenaline:
· It is a tonus hormone because it regulates the B.P except for the coronary artery, raise SP and DP of the heart.
Disorders:
· Pheochromocytoma:
· It is a tumour of adrenal medullary tissue: Hypersecretion of both epinephrine and norepinephrine occurs in this condition.
· It is characterized by the symptoms: headache, palpitation, blurred vision, dizziness, weakness, sweating, tachycardia, high B.P.
Treatment:
· It is treated by surgical removal of tumour: Beta-blockers are helpful to reduce the B.P. and heart rate.
· Pheochromocytoma:
· It is a tumour of adrenal medullary tissue: Hypersecretion of both epinephrine and norepinephrine occurs in this condition.
· It is characterized by the symptoms: headache, palpitation, blurred vision, dizziness, weakness, sweating, tachycardia, high B.P.
Treatment:
· It is treated by surgical removal of tumour: Beta-blockers are helpful to reduce the B.P. and heart rate.
| Zone | Hormone | Function | Excess | Deficiency |
|---|---|---|---|---|
| Zona glomerulosa | Mineralocorticoids (Aldosterone) [Secretion by Angiotensin K+ level] | Cl, Na+ reabsorption and K+ excretion Water retention [Thus regulates BP] | Conn's syndrome (water retention, hypokalaemia, metabolic alkalosis, hypertension) | |
| Zona fasciculata | Glucocorticoids | Gluconeogenesis Glycogendigsis (blood glucose) Lipolysis Anti-inflammatory Protein breakdown | Cushing syndrome (moon face, buffalo hump, abdominal striae, wasting of muscles, hypertension, osteoporosis) | Addison disease (Hyperpigmentation, loss of hair, anaemia, hypotension, indigestion, menstrual disorders.) |
| Zona reticularis | Sex corticoids (Mainly androgens) | Spermatogenesis in males Development and maintenance of secondary sexual characters Protein deposition in muscles. | Precocious puberty in males. Adrenogenital syndrome and Pseudohemaphroditism in females | Pseudohermaphroditism in males. |
| Medulla | Adrenaline Noradrenaline Dopamine | Mimic sympathetic activity Increase metabolism Fight and flight response | Hypertension |
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