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Name the 4 zones of the adrenal gland.
During what time of day is cortisol release the greatest?
*plasma cortisol levels measured early morning; 2
What protein activates a cholesterol channel in the mitochondria, allowing it to enter and be converted into pregnenolone? In which zones does this protein act upon?
StAR; 6 (Steroidal acute regulatory protein)
Name 2 long-term effects of ACTH.
transcription of synthesis enzymes
increase in number of LDL receptors
Why is aldosterone production exclusive to the zona glomerulosa?
alone possesses aldosterone synthase
How does high extracellular K+ affect synthesis and release of aldosterone?
increases synthesis and release of aldosterone; 8
Name 3 channels in the principle cells of the distal convoluted tubule/collecting duct that are enhanced by aldosterone.
K+ (ROMK) channels; 10
How does the body prevent cortisol from exerting a large mineralcorticoid effect?
11-beta-hydroxysteroid dehydrogenase converts cortisol into cortisone
How can licorice affect sodium retention?
increase sodium retention, leading to hypertension--"Mineralcorticoid excess syndrome"
Describe K+, renin levels, and blood pressure in Conn's syndrome.
low renin levels
increased blood pressure
Describe hydration, blood pressure, [Na], and [K] in hyposecretion of aldosterone.
hypotension (marked postural hypotension due to low blood volume)
Describe blood aldosterone, renin, and angiotensin 2 in hyposecretion of aldosterone.
increased angiotensin 2
How does cortisol affect protein metabolism?
increases proteolysis in all cells (except the liver)
How does cortisol affect lysosomes?
stabilizes lysosomal membranes to prevent release of proteolytic enzymes
How does cortisol affect synthesis of PGs and leukotrienes?
decreases both by decreasing phospholipase A2
What hormone is administered prior to premature births? Explain.
increases surfactant production
Describe 3 ways in which excess cortisol affects bone.
decreases formation and increases resorption
increases PTH and Calcitrol on bone (increased resorption)
How does excess cortisol affect Ca metabolism?
decreases absorption from GIT
increases excretion by kidneys
*negative Ca balance
What is the difference between Cushing's disease and syndrome?
Cushing's disease refers to increase release of ACTH from pituitary
Describe plasma ACTH and cortisol in Cushing's syndrome.
low ACTH (negative feedback)
What happens to the HPA axis of someone on chronic steroid therapy?
adrenal cortex atrophies because cortisol suppresses CRH and ACTH
Describe a situation in which secondary adrenal insufficiency results.
sudden withdrawal of glucocorticoids after prolonged therapeutic use
Is cortisol or aldosterone production more affected in secondary adrenal insufficiency?
ACTH has less effects on integrity of zona glomerulosa
What is the commonest enzyme deficiency causing hyposecretion of adrenal cortex hormones?
Explain how low cortisol and low aldosterone can cause salt-losing virilizing congenital adrenal hyperplasia.
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