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70 Cards in this Set
- Front
- Back
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Aldosterone is made where?
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adrenal cortex (zona glomerulosa)
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Cortisol is made where?
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adrenal cortex (zona fasciculata)
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DHEA is made where?
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adrenal cortex (zona reticularis)
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3 zones of adrenal cortex
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glomerulosa, fasciculata, reticularis
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Adrenal cortex secretion is regulated by what pituitary hormone?
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ACTH
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Adrenocotrical hormones are all derived from what compound?
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LDL cholesterol
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How does ACTH increase the amount of cholesterol available for the adrenal cortex?
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more LDL receptors and more enzymes to liberate cholesterol from LDL
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In the formation of the adrenocortical hormones, cholesterol is first converted into _______.
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pregnenolone
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Where in the cell does adrenocortical hormone synthesis occur?
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mitochonria or ER
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Aldosterone is a (mineralocorticoid or glucocorticoid)?
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mineralocorticoid
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Cortisol is a (mineralocorticoid or glucocorticoid)?
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mostly glucocorticoid
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Prednisone is a (mineralocorticoid or glucocorticoid)?
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glucocorticoid
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What is transcortin?
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a plasma protein used to transport cortisol
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By binding to transcortin, cortisol has a higher or lower half-life?
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higher half-life; stays in system longer
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To degrade the adrenocortical hormones; the liver conjugates them with ....
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glucaronic acid
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Why could liver damage lead to hyperaldosteronism?
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liver usually degrades the adrenal hormones; liver damage = can't degrade aldosterone
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Why do low levels of aldosterone lead to salt wasting?
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low aldosterone = less sodium uptake out of urine = more salt is lost in urine
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Low levels of aldosterone are associated with (high or low) blood potassium?
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high potassium in blood
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Why is cardiac shock a risk for patients with low aldosterone?
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aldosterone = more sodium into blood = more water follows into blood = higher BP. if there is a problem with this pathway, BP can drop too low
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Cortisol is a weak mineralocorticoid. What causes AME (apparent mineralocorticoid excess)?
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defect in 11B-hydroxysteroid dehydrogenase = build up of cortisol. normally 11BHSD converts cortisol into cortisone and cortisone doesn't act as a mineralocorticoid.
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Enzymes in licorice can cause AME by blocking which enzyme?
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11B hydroxysteroid dehydrogenase is blocked = build up of cortisol = apparent mineralocorticoid excess
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Aldosterone increases sodium uptake in what part of the nephron?
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collecting duct (and distal tubule)
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Even though aldosterone clearly increases sodium levels in the blood, why does [sodium] remain constant?
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water usually follow so the concentration is the same
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Why does long-lasting, excess aldosterone (over 1-2 days) actually lead to lower levels of sodium in the blood?
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long-term, excess aldosterone leads to an increase in arterial pressure = higher cardiac output = more glomerular filtration = sodium enters the tubular fluid faster than it is put back in by aldosterone
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What is pressure natriuresis and diuresis?
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rise in arterial pressure that leads to higher kidney excretion of salts and water
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Why do low levels of aldosterone lead to cardiac toxicity?
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low aldosterone = high blood potassium = heart weakness
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Aldosterone has what effect on potassium?
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moves potassium from blood into cells; low aldosterone = high potassium in blood; high aldosterone = low potassium in blood
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Why does excess aldosterone lead to alkalosis?
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sodium is reabsorbed into the renal epithelium antiport with acid; more sodium reabsorption = more acid excretion = alkalosis
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A patient with low aldosterone would have (more or less) salt in their sweat?
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more; low aldosterone = less salt reabsorbed from sweat into the body = more salt in sweat
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The receptor for aldosterone is located where in the cell?
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cytosol
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Why does aldosterone lead to up regulation of the sodium potassium pump?
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to create a gradient to move sodium through the channels into the renal epithelium (out of the urine)
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High levels of blood potassium would cause (more or less) production of aldosterone?
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more; aldosterone can move K into the cells and out of the blood
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High levels of angiotensin II would cause (more or less) production of aldosterone?
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more; stimulates release of aldosterone from adrenal cortex (glomerulosa)
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High levels of blood sodium would cause (more or less) production of aldosterone?
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less; don't need to put more sodium in the blood
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2 most important regulators of aldosterone levels?
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potassium levels and renin-angiotensin system
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ACE inhibitors have what effect on aldosterone levels?
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decrease; prevent angiotensin II formation; angiotensin II signals the adrenal cortex to release aldosterone
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How does cortisol promote gluconeogenesis?
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increase enzymes needed for AAs into glucose; brings AAs from muscle to the liver
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Cortisol has what effect on glucose usage by non-hepatic cells?
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decreases glucose usage
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What is adrenal diabetes?
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cortisol increases gluconeogenesis and decreases usage by cells = more glucose accumulation in blood = high insulin. but glucocorticoids inhibit insulin = constantly high blood glucose
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Cortisol has what effect on cellular protein usage in non-hepatic cells?
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decreases it; AAs are needed for glucoenogenesis so proteins are degraded and no longer made. usage increases in hepatic cells since the AAs are mobilized there
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Cortisol has what effect on blood AA levels?
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increased blood amino acid levels; break down proteins and prevent them from entering non-hepatic cells = accumulate in blood
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Why does cortisol mobilize fat from adipose tissue into the blood?
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to shift the system from using glucose for energy to using fat for energy. simulate starvation state = more gluconeogenesis
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Why is cortisol given to relieve cell stress?
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might cut off nutrient supply to damaged tissues and allow for creation of new cells
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5 stages of inflammation
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histamine release; erythema; protein leakage; leukocyte migration; fibrosis/healing
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Cortisol stabilizes the lysosomal membrane. Why does this help inflammation?
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most inflammatory enzymes are released from the damaged lysosomes
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Cortisol decreases permeability of capillaries. Why does this help inflammation?
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now plasma proteins don't leave circulation and stasis doesn't occur
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Cortisol has what effect on the immune system?
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suppresses it; can cause lymphoid tissue atrophy
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How does cortisol reduce fever?
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reduces IL-1 release from leukocytes
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Why is cortisol given to transplant patients?
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suppresses immune system; can cause lymphoid tissue atrophy so less chance of tissue rejection
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Cortisol has what effect on hematopoiesis?
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increases it
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ACTH is regulated by what hypothalamic hormone?
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CRH (corticotropin releasing hormone)
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CRH (corticotropin releasing hormone) is made where
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hypothalamus
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ACTH has what effect on cAMP production
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increases it to activate the enzymes needed for steroid production
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What is the rate-limiting step in steroid production?
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step 1; conversion of cholesterol to pregnenolone
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Stress leads to (high or low) levels of ACTH?
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high levels
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High levels of cortisol have what effect on CRH (from hypothalamus) and ACTH (from ant. pituitary) release
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decreases; negative feedback loop
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Cortisol is highest at what time of day?
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noon
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Why does increased ACTH synthesis also lead to melanocyte stimulating hormone also?
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in the process of making ACTH, first POMC (a precursor) is formed that can also become MSH
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Pituitary corticotrophs have which enzyme to cleave POMC to form ACTH?
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PC1 (prohormone convertase 1), not PC2
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PC2 cleaves POMC into which hormones?
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MSH and endorophins, but not ACTH
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What is Addson's Disease?
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adrenal insufficiency
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What is primary adrenal insufficiency?
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lack of adrenal gland to make hormones
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What is secondary adrenal insufficiency?
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lack of pituitary or hypothalamus to make ACTH or CRH
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Low aldosterone leads to what urine content?
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high Na, Cl and water
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Polycythemia and viscous blood are associated with a lack of which adrenal hormone?
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aldosterone; [RBC] increases as blood volume decreases
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Why do patients with Addson's disease have more melanin production?
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if they have primary adrenal insufficiency, there will be no adrenal hormones to negative feedback on the ACTH production. higher ACTH production = more Melanin stimulating hormone
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What is Cushing's Syndrome?
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excess endogenous ACTH (perhaps tumor of pituitary)
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What is dexamethosone?
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synthetic glucocorticoid
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What is Conn's syndrome?
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primary aldosteronism (high aldosterone due to glomerulosa tumor)
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In patients with primary aldosteronism, do we see (high or low) levels of renin?
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low; high aldosterone inhibits renin production
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