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31 Cards in this Set
- Front
- Back
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Derangements in Na+ transport alter what?
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Blood pressure
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Na+ affects blood pressure because it is the major determinant of blood _______________.
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osmolality
(body will preferentially choose to regulate osmolality over BP) |
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The body responds to increases in Na+ intake by triggering an increase in what?
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fluid intake - to keep osmolality constant
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How does the kidney deal with filtering toxins like Aluminum in Maalox?
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filters all plasma and only reabsorbs solutes it wants
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Approximately what percent of Na+ is reabsorbed in the nephron?
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99.6%
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Most Na+ reabsorption takes place where? What are the other areas where Na+ is reabsorbed?
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-proximal convoluted tubule (PCT) - 65%
-thick ascending limb of loop of henle - 25% -distal convoluted tubule (DCT) - 5% -collecting duct - 2-4% |
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The normal intracellular charge in the proximal tubular cells is ~_____mv
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-70 mV
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What creates low Na+ concentration in the cell?
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The Na+/K+ ATPase on the basolateral side - transports Na+ out and K+ into the cell
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What four Na+ transporters are on the luminal side of the cell?
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-Na+/H+ transporter (Na+ in, H+ out) - NHE3
-Na+/glucose transporter (Both in) - Sglut2 -Na+/PO4 transporter (Both in) -Na+/amino acid transporter (Both in) |
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Where do the protons being pumped out come from?
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Carbonic anhydrase - creates carbonic acid in the cell which dissociates to HCO3- and H+
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A defect in all four of these transporters is called what?
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Faconi syndrome
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Describe Na+ reabsorption in the thick ascending limb.
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-Via the NKCC2 transporter
-1 Na+, 1 K+, and 2 Cl- in the cell |
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Which is the rate limiting step in this transporter? How is this corrected for?
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-K+ - rate-limiting
-recycled back out into the lumen via ROMK (defect in ROMK --> excess loss of Na+ in urine) |
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How does Cl- then leave the cell on the basolateral side?
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ClC1 transporter - passive
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What kind of drugs block NKCC2?
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-Loop diuretics (most potent)
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Describe Na+ uptake in the distal convoluted tubule.
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-via the NCC transporter - 1 Na+ in and 1 Cl- in
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What kinds of drugs act on the NCC transporter?
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Thiazides (less potent)
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What are the two types of cells found in the collecting duct? Which type are important for Na+/H20 reabsorption? What is the function of the other type?
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-principal cells - important for Na+ reabsorption
-intercalated cells - acid-base balance |
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The sodium transporter in the collecting duct is called what?
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-ENaC - epithelial Na+ channel
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Conditions that increase Na+ absorption also increase ______________ excretion.
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Potassium
(Na+ in makes lumen more negative, more K+ goes out) |
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Diuretics that block ENaC have what effect on potassium?
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-None - don't cause K+ loss in urine "potassium sparing"
-are weak diuretics |
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What 3 cell types work together to coordinate NaCl transport?
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-principal cell (Na+ in via ENaC); (Na+/K+ ATPase on basolateral side)
-intercalated cell, type B (Cl- in, HCO3- out); (Cl- out on basolateral side) -intercalated cell, type A (H+ out) |
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What effect do aldosterone, angiotensin II, and sympathetic stimulation have on Na+ reabsorption?
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-increase Na+ reabsorption
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What two hormones decrease Na+ reabsorption?
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-ANP and NO
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What kinds of drugs can be used to modestly alter Na+ uptake in the proximal tubule by altering activity of the NHE 3 transporter (Na+ in, H+ out)?
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Carbonic anhydrase inhibitors
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What drug affects Na+/K+ ATPase activity in all segments of the nephron?
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Digoxin
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What happens with diuretic use over time?
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-other portions of the nephron adapt making it less effective
-combination therapy often needed |
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Syndrome in which NCC expression is increased, causing hypertension, hyperkalemia, and volume expansion
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Gordon's Syndrome
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Syndrome in which NCC expression is decreased, causing hypotension, low plasma volume, hypokalemia and hypocalciuria
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Gittelman's Syndrome
(less severe than Bartter's syndrome) |
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Syndrome in which ENaC expression is increased, causing hypertension, hypokalemia, and volume expansion
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Liddle's syndrome
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Syndrome affecting NKCC2, ROMK or ClC1 in the thick ascending limb, causing hypotension, low plasma volume, hypokalemia and hypercalciuria
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Bartter's syndrome
(more severe than Gittelman's syndrome) |
