Term
| What agents can be used to treat osteoporosis? |
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Definition
| bisphosphonates, weight-bearing exercise, calcium and vitamin D, pulsatile PTH, calcitonin, gonadotropins |
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Term
| A child exhibits proximal muscle weakness and enlarged calves. What is the disease and how is it inherited? |
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Definition
| Duchenne muscular dystrophy, X-linked |
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Term
| What are 4 types of epithelial cell junctions? What are 4 proteins involved in nonepithelial adhesion mechanisms? |
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Definition
- Zona occludens (tight)
- Zona adherens (IM junctions)
- Macula adherens (desmosome)
- Gap junctions
- Selectins, integrins, ICAMs, cadherins |
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Term
| What class of drugs inhibits the Na+/2Cl-/K+ symporter in the thick ascending limb? |
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Definition
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Term
| What determines how much water is reabsorbed in the distal tubules and the collecting ducts? |
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Definition
- ADH/vasopressin: acts on Principal cells, tells to insert aquaporins
- Collecting duct concentrates urine based on ADH |
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Term
| What two types of cells compose the collecting duct and the last segment of the distal tubule? What do they do? |
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Definition
- Principal cells – reabsorb H20 and Na+, secrete K+
- Intercalated cells – Secrete H+ or HCO3-, reabsorb K+ |
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Term
| What are the two types of intercalated cells? |
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Definition
| H+-secreting alpha cells, HCO3- secreting cells (b cells) |
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Term
| What class of diuretic directly affects principal cells? |
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Definition
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Term
| What affect does aldosterone have on the intercalated cells and principal cells of the collecting duct? |
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Definition
• Intercalated cells- stimulates acid secretion
• Principal cells- more Na reabsorption, K secretion |
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Term
What drugs antagonize aldosterone’s action on the principal cells of the collecting duct,
thereby promoting Na+ excretion and inhibiting K+ excretion? |
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Definition
| Aldosterone antagonists: spironolactone, eplerenone (these are also K sparing diuretics) |
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Term
| What are the critical steps involved in excreting dilute urine? |
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Definition
• Dilution of fluid in the thick ascending segment (to 100 mOsm/kg H2O) as solute is reabsorbed and water remains in lumen (due to the impermeability of water in the thick ascending limb)
• The absence of ADH renders the distal tubule and cortical collecting duct impermeable to water
• Tubular fluid is diluted even more as solute is removed from the tubular fluid in the distal tubule and cortical collecting duct but water remains
• Because of the low fluid osmolality in the collecting duct and the slight permeability of the medullary collecting duct to urea, urea enters the tubule from the medullary interstitium thereby keeping the osmolality of the medullary interstitium low |
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Term
| What are the critical steps involved in excreting concentrated urine? |
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Definition
1) Dilution of fluid in the thick ascending segment (to 100 mOsm/kg H2O) as solute is reabsorbed and water remains in lumen (due to the impermeability of water in the thick ascending limb)
--The reabsorption of solute without water in the thick ascending limb helps to increase the osmolality in the interstitium
2) The presence of ADH renders the distal tubule and collecting duct permeable to water
--As water leaves the tubular fluid to an interstitium of high osmolality, the osmolality of the tubular fluid increases (and equals the osmolality of the interstitium)
3) The presence of ADH increases the permeability of the last portion of the medullary collecting duct to urea
--As the tubular fluid has a high concentration of urea (due to the reabsorption of water in the initial segments of the collecting duct and impermeability of those segments to urea), urea enters the
interstitium as it goes down its concentration gradient from the last portion of the medullary collecting duct
--As urea leaves the last portion of the medullary collecting duct (to go into the interstitium) and enters the loop of Henle (from the interstitium), it becomes more and more concentrated within the interstitium thereby increasing the osmolality of the interstitium
--This high osmolality serves to concentrate the urine in the collecting ducts (which are permeable to water which allows the fluid in the cortical collected duct to achieve the same osmolality as the fluid in the medullary interstitium) |
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Term
| What segment of the renal tubule matches the following statements? |
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Definition
• Reabsorbs 67% of the fluid and electrolytes filtered by the glomerulus – proximal
• Segment responsible for concentrating urine – collecting duct, thin descending
• Site of secretion of organic anions and cations - proximal
• Always impermeable to water - TAL
• Permeable to water only in the presence of ADH – LDT, collecting duct
• Site of the Na+/2Cl-/K+ co-transporter – thick ascending limb
• Site of isotonic fluid reabsorption – proximal tubule
• Site responsible for diluting urine – thick ascending limb
• Only site where glucose and amino acids are reabsorbed - proximal
• Water reabsorption in the Loop of Henle – thin descending limb |
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Term
| What are the two main cell types of the collecting duct? |
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Definition
- Principal cells
- Intercalated cells |
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Term
| What affect does aldosterone have on the intercalated cells and principal cells of the collecting duct? |
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Definition
• Intercalated cells- secrete acid
• Principal cells- Na reabsorption, K secretion |
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Term
| What class of drugs inhibits the Na+/2Cl-/K+ symporter in the thick ascending limb? |
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Definition
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Term
What type of diuretic is the following drug?
• Triamterene
• Acetazolamide
• Hydrochlorothiazide
• Bumetanide
• Spironolactone
• Chlorothiazide
• Ethacrynic acid
• Mannitol
• Metolazone
• Chlorthalidone
• Furosemide
• Amiloride
• Torsemide |
|
Definition
• Triamterene – K+sparing
• Acetazolamide – carbonic anhydrase inhibitor
• Hydrochlorothiazide - Thiazide
• Bumetanide – Loop
• Spironolactone – K+ sparing diuretic
• Chlorothiazide - Thiazide
• Ethacrynic acid – Loop, but not sulfa
• Mannitol - Osmotic
• Metolazone - Thiazide
• Chlorthalidone - Thiazide
• Furosemide - Loop
• Amiloride – K+sparing
• Torsemide - Loop |
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Term
What diuretic or class of diuretic would be most useful in the following situation?
• Acute pulmonary edema
• Idiopathic hypercalciuria (➡ calcium stones)
• Glaucoma
• Mild to moderate CHF with expanded ECV
• In conjunction with loop or thiazide diuretics to retain K+
• Edema associated with nephrotic syndrome
• Increased intracranial pressure
• Mild to moderate hypertension
• Hypercalcemia
• Altitude sickness
• Hyperaldosteronism |
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Definition
• Acute pulmonary edema - Loop
• Idiopathic hypercalciuria (➡ calcium stones) - Thiazide
• Glaucoma – Mannitol, acetazolamide
• Mild to moderate CHF with expanded ECV – Thiazide or loop
• In conjunction with loop or thiazide diuretics to retain K+ - K+sparing
• Edema associated with nephrotic syndrome - Loop
• Increased intracranial pressure – Mannitol
• Mild to moderate hypertension - Thiazide
• Hypercalcemia - Loop
• Altitude sickness - Acetazolamide
• Hyperaldosteronism – Spironolactone or eplerenone |
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Term
| What is the site of action of mannitol? (FA11 p474) (FA12 p525) |
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Definition
| Proximal convoluted, early distal |
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Term
| What is the site of action of the thiazides? |
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Definition
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Term
A patient with heart failure exacerbation needs medical diuresis but has a sulfa allergy.
What diuretic can be used? |
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Definition
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