Glucocorticoid include cortisol (hydrocortisone) and corticosterone: Cortisol is more potent and has 95% of glucocorticoids activity while corticosterone has only 4% of glucocorticoid activity.
Source:
These are secreted mainly by zona fasciculata of adrenal cortex and a small quantity by zone reticularis·
2.Nature:
Glucocorticoids are C2l steroids having 21carbon atoms.
3. Functions/Actions of Glucocorticoids:
Aldosterone (a mineralocorticoid) is, a life saving hormone, whereas cortisol is a life protecting hormone, withstanding stress& trauma in life.
I). Effect on carbohydrate metabolism:
They increase the blood glucose level by; promoting gluconeogenesis in liver from amino acids & inhibiting glucose uptake and utilization by peripheral cells.
ii). Effects on Protein metabolism:
They catabolise proteins and decrease the proteins in the cells. They increase plasma amino acids and protein content in
liver
.
iii). Effects on Fat Metabolism:
They cause mobilization and redistribution of fats. So utilization of fat,energy increases.
iv). Effects on mineral & Water metabolism:
may promote ‘the retention of sodium & calcium and increase the excretion of potassium. May accelerate the excretion of water in response of large intake of water.
V). Effects on Muscles:
They increase the release of amino acids from muscle by catabolism of proteins. So hypersecretion leads to muscular weakness.
vi). Effects on blood cells &Vessels:
They decrease eosinophils by destroying them in reticuloendothelial cells. They also decrease basophils and lymphocytes, but increase circulating neutrophils, RBC. and platelets. The constrictor action of adrenaline & noradrenaline on blood vessels occur only in the presence of glucocorticoids.
vii). Effects on other hormones:
Some hormonal actions are executed only in the’ presence of glucocorticoids. It is permissive action of glucocorticoid. Such as Calorigenic actions of glucagons and lypolytic actions of catecholamines
viii). Resistance to Stress:
They offer increased resistance to the body against any physical or menial stress. The exact cause of increase resistance of glucocorticoids is not known.
ix). Anti-inflammatory effects:
They prevent the inflammatory changes in the cells caused by an infection or. Injury. They also prevent various reactions in allergic conditions.
X). Immunosuppressive Effects:
They suppress the immune system of the body by decreasing circulating T lymphocytes (suppressing lymph nodes & thymus).
Regulation of secretion
Their secretion is regulated by anterior pituitary by anterior pituitary by secreting ACTH. In tum, ACTH secretion is regulated by hypothalamus through corticotrophin releasing factor (CRF).
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