Adrenal Hormones Flashcards
Where are the corticosteroids synthesised?
Cortex
where are the adrenal glands located
Loosely embedded above kidney
Where are the the catecholamines synthesised
Medulla
What is produced in each section of the cortex
zona glomerulosa - mineralocortioids
zona fasiculata- glucocorticoids
zona reticularis - adrenal androgens
What is the binding make up of cortisol
85% bound to corticosteroid - binding globulin
10% albumin
5% unbound
What is aldosterone bound to
60% bound to primary albumin
Role of glucocorticoids
Regulation of cortisol secretion
Stimulus of glucorticoids
Primary stimulus
Where is cortisol measured
Urine
what will normal coritsol show as
Transcortin almost fully saturated
What will high cortisol look like in the urine
Free cortisol - high
urinary free cortisol high
Actions of glucocorticoids
Muscle - net loss of amino acids
Fat cells - lipolysis + glucose sparing effects
Immune system and inflammation will be supressed
Liver - gluconeogenesis + glycogenesis
What does cortisol directly do?
Directly promotes rapid supply of glucose to tissue
How is cortisol a permissive hormone
Affects the other counter-regulatory hormones
required for expression of adrenergic and angiotensin II receptors in CVS
What does an XS of glucocorticoid cause
Hypothalamic tumour
ant pituary tumour (60-70%) cases - cushings disease
adrenal tumour
ectopic tumour
latrogenic cushings syndrome - exogenous glucocorticoids
What are the effects of glucocorticoids on carbohydrate metabolism?
Hyperglycaemia- increase in blood glucose levels (twice normal size)
“adrenal diabetes”
What are the effects of glucocorticoids on protein metabolism?
Protein shortage- muscle weakness Stretch lines easy bruising thinning of skin - inhibition of collagen osteoporosis - pathological fratures delayed healing suppression of immune system
Features of CUSHINGs disease
Central obesity, Collagen fibre weakness, Comedones (acne)
Urinary free cortisol and glucose increase
Striae, Supressed immunity
Hypercortisolism, Hypertension Hyperglycaemia, Hypercholesterolaemia
Iatrogenic (admin of corticosteroids
Noniatrogenic (Neoplasms)
Glucose intolerance, Growth retardation
Role of mineralocorticoids
regulation of aldosterone secretion
What is the principle stimulus for secretion of aldosterone
Angiotensin II - principle stimulus for secretion of aldosterone
What is the action of aldosterone
Increase in Na+/H20 absorption
increase in K+/H+ secretion
increase in blood volume/BP
What does a deficiency in aldosterone lead to?
- Increase loss of Na/H20 in urine- dehrydration, plasma depletion + hypotension
- Increased renal retention of K+ and hyperkalaemia, caridac availabilty and can cause ventricular fibrilation
- Renal retention of H+ producing a metabolic acidosis
Cause of primary hyperaldosteronism
Adrenal adenoma
Cause of secondary hyperaldosteronism
Overactivity of renin-angiotensin system
