Guyton Adrenocortical hormones Flashcards
List the layers of the adrenal cortex from out to inside
zona glomerulosa
zona fasciculata
zona reticularis
What enzyme is needed for aldosterone production, what layer of the cortex is it produced by and what regulates its production?
aldosterone synthase
regulated by angiotensin II and K levels
Where is the adrenal cortex is cortisol produces and what regulates its production?
mostly zona fasciculata, some in zona reticularis
ACTH
How are cortisol and aldosterone carried in the plasma? What is their half-life?
cortisol - cortisol-binding globulin/transcortin (most), some albumin - 90-95% carried –> long half life 60-90 minutes
aldosterone - less protein binding (60%), shorter half life (20 min)
How are adrenocortical hormones cleared from the plasma?
degraded and conjugated by the liver –> some excreted into bile, some circulation –> kidneys
How does liver or kidney disease affect adrenocortical hormone plasma levels?
liver disease –> increases cc of active steroid hormones
kidney disease –> increases cc of inactivated steroid hormones
What part of the nephron does aldosterone act on?
COLLECTING TUBULES, some distal convoluted tubule and collecting ducts
Explain the aldosterone escape and how this affects Na cc versus BP
increased aldosterone –> increased sodium retention and BP/increased body water
–> increased GFR –> pressure natriuresis and pressure diuresis –> returns renal Na and water output back to normal
Explain the role of ADH in an aldosterone depleted animal
low ECV from aldosterone depletion –> induces ADH release –> free water retention –> can worsen hyponatremia
How can excessive aldosterone cause alkalosis?
aldosterone –> causes H+ excretion in exchange for K in the intercalated cells of the cortical collecting tubules –> stimulates H+ excretion –> more aldosterone –> more H+ excretion –> alkalosis
Explain how aldosterone affects Na and K movement in the kidneys
- aldosterone diffuses into the cytoplasm –> acts on cytoplasmic mineralocorticoid receptors –> moves into the nucleus –> starts inducing transcription to produce cell surface proteins for electrolyte transport
- Na/K ATPase on basolateral membrane –> Na out and K into the cell
- Na moves down cc gradient into the cell pulling water and Cl- (luminal Na channels)
- K channels for exiting on luminal membrane
List 5 factors that play into the regulation of aldosterone secretion
- angiotensin II –> increases
- hyperkalemia –> increases
- hypernatremia –> decreases
- atrial natriuretic peptide –> decreases
- ACTH
What are the effects of cortisol on the glucose, protein, and fat metabolism?
- increased gluconeogenesis –> increased glucose release?
- decreased peripheral glucose uptake
- inhibits insulin functions
- increased protein mobilization, decreased protein synthesis (but increases liver and plasma protein levels)
- increased fat mobilization –> high triglycerides in plasma
Explain how cortisol increases glucose levels
- increased gluconeogenesis
- inhibits insulin
- decreased glucose uptake by cells
List the 5 steps of inflammation
- cytokine release (DAMPs) from damaged tissue cells
- increased blood flow
- plasma extravasation
- leukocyte infiltration
- fibrosis
