The Adrenal Hormones
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17 terms
Terms | Definitions |
|---|---|
 Which hormones are released by the adrenal cortex? | cortisol (glucocorticoids), testosterone, aldosterone (mineralocorticoids). (steroid hormones) |
| Which hormones are released by the adrenal medulla? | epinephrine and norepinephrine. (catecholamines) |
| Adrenocortical hormones | -mineralocorticoids and glucocortocoids (aldosterone and cortisol) -act on intracellular nuclear receptors -receptor plus hormone unfolds and binds to DNA at HORMONE RESPONSE ELEMENTS-leads to transcription of genes -increases RNA polymerase activity and production of specific mRNAs -increases protein synthesis |
| Nuclear Receptors | Receptors for lipophilic hormones - function within the cell nucleus to activate genetic transcription (production of mRNA). Must be activated by binding to its hormone ligand before it can bind to a specific region of DNA. |
| Which drugs activate nuclear receptors? | • Oestrogen Receptor Agonists - for hormone replacement therapy in postmenopausal women • Glucocorticoid Receptor Agonist - for inflammation |
| Which drugs antagonize nuclear receptors? | -SPIRONOLACTONE. mineralocorticoid receptor antagonists-for oedema due to liver cirrhosis and for heart failure. -TAMOXIFEN. oestrogen receptor antagonists-for prevention and treatment of breast cancer. -BICALUTAMIDE/CASODEX. androgen receptor antagonists-treatment of prostrate cancer. |
| Aldosterone (mineralocorticoids) | -aids in regulating electrolytes and water balance. -retain Na in exchange for K -retains water -production mainly regulated by renin/angiotensin system. -aldosterone antagonist-spironolactone-used as a K sparing diuretic. -aldosterone acts on distal renal tubes to increase Na reabsorption and increased excretion of K and H. -aldosterone nuclear receptors occur only in kidneys. -spironolactone is a competitive antagonist of aldosterone at these receptors. -the effect of the aldosterone-receptor complex interaction with DNA is to increase the number of Na channels in the membrane of the renal cell. |
| Glucocorticoids | -metabolic -negative feedback on anterior pituitary/hypothalamus -anti-inflammatory and immunosuppressive effects |
| Glucocorticoids (metabolic actions) | -CBH decreased uptake of glucose but increased breakdown of protein to glucose-HYPERGLYCAEMIA -Proteins increased breakdown and reduced synthesis -Fat increased breakdown, redistribution -Raise plasma glucose levels to provide energy to combat stress. |
| Glucocorticoids (anti-inflammatory and immunosuppressive effects) | REDUCE: -blood vessel dilation/leakage -production of mediators -inflammatory and immune cell activity DECREASED MEDIATORS: -glucocorticoids inhibit phopholipase A2 -this blocks production of arachidonic acid, prostaglandins and leukotrienes from cell membrane phospholipid. |
| Hydrocortisone | -taken orally -replacement cortisol |
| Beclomethasone | -inhaled -asthma |
| Prednisolone | -taken orally -inflammatory and |
| Dexamethasone | -taken orally -inflammation |
| Betamethasone | -topically -skin inflammation |
| Adverse effects of glucocorticoids include... | -suppression of response to infection -suppression of synthesis endogenous glucocorticoid -metabolic effects -osteoperosis |
| Catecholamines (adrenal medulla hormones) | -adrenaline and noradrenaline (to a lesser extent) secreted in response to the sympathetic nervous system (fight or flight) -Stimulation releases glucose from the liver and fatty acids from adipose tissue -actions of epinephrine (adrenaline) in these tissues are mediated by elevations in cyclic AMP levels. -also maintain BP through ionotropic effects on the heart and vasoconstrictor actions -people with hypertension can be treated with beta-adrenoreceptor antagonists to reduce cardiac rate -failure of adrenal medulla is rare but causes hypotension -tumours of adrenal medulla secrete catecholamines causing hypertension and must be removed surgically. |
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