The following points highlight the functions of various types of cortical hormones. The Functions are: 1. Mineralocorticoids 2. Functions of Glucocorticoids 3. Functions of Adrenal Sex Steroids.
Cortical Hormones # Mineralocorticoids:
This hormone is mainly secreted from zona glomerulosa.
Principal functions are given below:
1. On Mineral Metabolism:
(a) Mineralocorticoids help to increase the rate of tubular reabsorption of sodium (Na+) from the renal tubules.
(b) It increases the excretion of K+ from distal convoluted tubule and collecting tubule to maintain the K+ concentration.
(c) Helps in retention of NaCI.
(d) Increased secretion may cause alkalosis while decreased secretion promotes acidosis.
2. On Water Metabolism:
Helps in absorption of water from renal tubules to maintain the water balance.
3. On Blood Protein:
Helps in increase of haemoglobin and plasma protein.
4. On Fat:
Stimulates fatty acid synthesis.
5. On Cardiovascular System:
(a) Hyper-secretion increases the cardiac output, while hypo-secretion reduces the cardiac output.
(b) Excess secretion increases the arterial blood pressure.
6. On Fluid Volume:
(a) This hormone stimulates the thirst centre and as a result person shows thirsty.
(b) Helps to increase the plasma volume.
7. On Cellular Mechanism:
Helps in diffusion of lipid in cellular membranes of tubular epithelial cells.
Cortical Hormones # Functions of Glucocorticoids:
Glucocorticoids are primarily secreted from zona fasciculata.
Glucocorticoids possess the following functions:
1. On Carbohydrate Metabolism:
(a) Promotes gluconeogenesis in liver specially from proteins to increase blood glucose level.
(b) Stimulates glycogenesis in liver and muscle.
(c) Helps in phosphorylation of glucose- 6-P.
(d) Helps in absorption of glucose from intestine and renal tubule.
2. On Protein Metabolism:
(a) It stimulates protein synthesis in liver, but reduces protein synthesis in muscle.
(b) Glucocorticoids accelerate the breakdown of protein and inhibit amino acid uptake in extra-hepatic cells.
(c) It depresses amino acids transport into muscle cells.
(d) It enhances transport of amino acids in hepatic cells.
(e) It promotes urea synthesis in liver in presence of arginase and argino succinate synthetase.
3. On Fat Metabolism:
(a) Glucocorticoids increase lipolysis in adipose tissue and may raise free fatty acids in plasma.
(b) It stimulates the synthesis of triglycerides in the liver.
(c) Helps in metabolism of fatty acids to ketone bodies.
(d) Stimulates fat absorption from the intestine.
(e) It stimulates the mobilization of fatty acids and glycerol from adipose tissue in the blood.
4. On GI System:
(a) It stimulates oxyntic cells of stomach for secretion of HCI.
(b) It stimulates secretion of trypsinogen and pepsinogen.
(c) It inhibits absorption of calcium from small intestine.
5. On Nervous System:
(a) It influences the survival neurons.
(b) Maintains the structural integrity of brain.
(c) Excess secretion leads to reduction in threshold of electrical stimulation of brain which may cause convulsion.
6. On Ca++ metabolism:
(a) It reduces intestinal Ca++ absorption.
(b) It increases urinary Ca++ excretion.
7. On Respiratory System:
It causes maturation of foetal lung.
8. Effects on Cardiovascular System:
(a) It stimulates cardiac output.
(b) It increases blood pressure by enhancing the action of catecholamine’s.
(c) It reduces capillary permeability.
9. On Muscular System:
It causes loss of muscle power.
10. On Inflammatory and Immunologic Effects:
(a) It inhibits inflammatory and allergic reactions.
(b) Decreases the number of circulating monocytes, eosinophil’s and lymphocytes.
(c) Reduces the migration of leucocytes into affected tissue.
(d) Prevents histamine release from mast cells.
(e) Inhibits the synthesis of IL-1.
11. On RBCs:
It increases red blood cells count.
Cortical Hormones # Functions of Adrenal Sex Steroids:
Zona reticularis secretes adrenal sex steroids.
Principal functions of sex steroids are given below:
1. Effects in Males:
(a) May influence the growth and differentiation of secondary sex organs and features including pubic and axillary hair.
(b) The adult individual can cause opposite sex attraction, coarsening of the voice.
(c) Helps is growth of muscular, growth of sex glands and increases BMR.
2. Effects in Females:
(a) These hormones may be responsible for libido in women.
(b) Overproduction may cause hirsutism and virilization.
(c) Hyper-secretion may cause involution of female secondary sex characters.
(d) May cause development of mammary gland, more subcutaneous fat, less body hair and feminine voice.