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80 Cards in this Set
- Front
- Back
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What transporter is blocked by loop diuretics?
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Na-K-2Cl transporter in the ascending limb of the loop of henle
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What transporter is blocked by thiazide diuretics?
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Na-Cl cotransporter in the DCT
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Where does ADH exert its effect?
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Principal cells of the collecting duct by increasing the number of aquaporins on the surface
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What hormone regulates ENaCs?
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Aldosterone
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What is regulated by aldosterone?
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Na/H exchanger of the PT
Principal cell ENaCs Principal cell luminal K channels H-ATPase of type A intercalated cells |
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What inhibits the Na-PO4 transporter in the proximal tubule?
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PTH
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What regulates the Ca2+ channels of the DCT?
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PTH
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Where is the Na-K-2Cl transporter?
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DCT
All is uptake |
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What effect does PTH have on phosphate?
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Increases Phosphate excretion
Increases phosphate release from bone |
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What effect does PTH have on calcium?
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Increases Ca reabsorption & Ca release from bone
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What stimulates PTH release?
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Decreased plasma calcium
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What stimulates vitamin D production?
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Increased PTH
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How is HCO3 reabsorbed?
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Via carbonic anhydrase in PT
Produced by combination of water & CO2 in the epithelial cells-->HCO3 + H+ H+ secreted to lumen by type A cells (H-ATPases & H-K exchangers) while bicarbonate is secreted to the interstitium |
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How do kidneys excrete an alkaline load?
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Decrease bicarb reabsorption in the CCD
Type B intercalated cells can secrete HCO3 produced in the cells via a HCO3-Cl antiporter |
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How do kidneys excrete an acid load?
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Generate new bicarbonate
Protons are secreted bound to HPO4 or as ammonium |
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What is the effect of ouabain?
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Ouabain inhibits the Na-K ATPase on the basolateral membrane
This decreases kidney function as the Na gradient is decreased |
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What is the effect of angiotensin II?
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Stimulates aldosterone release
Increases PT apical Na transporters to increase Na reabsorption This increases BP & fluid retention |
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How is renin secretion controlled?
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1. renal sympathetic nerves stimulate renin secretion from granular cells
2. changes in systemic BP deform granular cell memebranes-->renin secretion 3. MD stimulates renin secretion when it senses low salt concentration |
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What are the 2 effects of high salt flow past the MD?
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Vasoconstriction of glomerular capillaries-->decreased GFR
Reduced renin secretion-->reduced ATII levels-->vasodilation-->increased GFR |
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What happens when there is not enough Ca on cell membranes?
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Inappropriate depolairization
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What type of collagen is in bone?
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Type I
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What is the origin of osteoclast?
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Monocytes
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How does vitamin D stimulate GI uptake of calcium?
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Activatino of Ca-ATPase
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What is the major effect of vitamin D?
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Stimulation of GI reabsorption of calcium & phosphate by the intestine
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How is calcium handling by the kidney?
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TAL & PT: paracellular reabsorption
DCT: basolateral Na-Ca exchangers & Ca-ATPases set up gradient for Ca entry via channels |
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How does PTH regulate Ca uptake?
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PTH controls the apical Ca channel.
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What effect do thiazide diuretics have on Ca handling?
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Thiazide diuretics block the NaCl transporter in the DCT
This increases the Na gradient for the Na-Ca exchanger on the basolateral membrane This increases Ca reabsorption |
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What effect does acidosis have on Ca handling?
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Acidosis inhibits Ca reabsorption
Alkalosis increases Ca reabsorption |
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What effect do loop diuretics have on Ca handling?
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Loop diuretics block the Na-K-2Cl transporter
This abolishes the gradient that promotes reabsorption of Ca So loop diuretics decrease Ca reabsorption |
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How does the kidney handle phosphate?
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Phosphate is reabsorbed in the PT by a Tm-limited system.
Apical Na-Pi transporters bring Pi into cells |
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How does PTH regulate phosphate handling?
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PTH increases intracellular [cAMP]
This causes increased endocytosis of the Na-Pi transporter PTH decreases renal reabsorption of Pi |
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What are the consequences of primary hyperparathyroidism?
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Hypercalcemia
Hypophosphatemia High plasma PTH Hypercalciuria (filtered load exceed reabsorptive capacity) S&S: kidney stones, bone disorders |
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What role does ammonium have in the kidney?
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Ammonium helps excrete an acid load.
Glutamin-->NH4+ + HCO3- HCO3- is reabsorbed NH4+ is secreted via apical Na-NH4 exchanger |
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What is titratable acid?
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HPO4
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What is normal HCO3?
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24
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What is normal PCO2?
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40
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What is the Henderson-Hasselbach equation?
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pH=pk+log(HCO3/(.03xPco2)
pH=6.1+log(24/1.2)=7.4 |
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What is the equation for bicarbonate buffering?
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CO2+H2O<-->H2CO3<-->H+ + HCO3-
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What stimulates K uptake by cells?
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Insulin
Epinephrine Alkalosis |
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What stimulates K+ release by cells?
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Exercise (loss of K)
Acidosis Tissue damage |
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What is the electrical consequence of hypokalemia?
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hyperpolarization
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What is the electrical consequence of hyperkalemia?
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depolarization
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Where is most K reabsorbed?
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PT
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Where is reabsorption of Ca regulated?
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DCT
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Where is reabsorption of K regulated?
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DCT & collecting ducts
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How is K reabsorbed in the PT?
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Paracellular
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How is K reabsorbed in the loop?
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Na-K-2Cl
Paracellular |
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On a low K diet, how is K handled by the kidney?
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PT & TAL of loop reabsorb K
DCT reabsorbs K Principal cells secrete little Intercalated cells reabsorb K via H-K-ATPase |
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On a high or normal K diet, how is K handled by the kidney?
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PT & TAL of loop reabsorb K
DCT secretes K Principal cells secrete K Intercalated cells reabsorb K via H-K-ATPase |
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How is K secretion in the CCD regulated?
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Plasma K: increased plasma K increases K secretion
Aldosterone stimulaes K secretion Tubular Na levels: high levels increase K secretion |
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How does plasma K regulate K secretion in the CCD?
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Increased plasma K is taken up into principal cells-->increased ICF K
This stimulates the basolateral Na-K ATPase But K still can't enter the lumen unless apical K channels are open (under control of aldosterone) |
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What stimulates release of aldosterone?
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Angiotensin II
Increasing plasma K |
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What inhibits release of aldosterone?
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ANP
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What effect does aldosterone have on K?
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Activates basolateral Na-K ATPases
Activates luminal K channels Activates ENaC channels-->further activation of basolaterla Na-K ATPase |
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How do tubular Na levels regulate K secretion?
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Na in the lumen increases ICF Na
This stimulates the Na-K ATPase & increases gradient for K to leave via K channels Increases K secretion |
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What are the potassium-sparing diuretics?
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Aldosterone blockers: block Na-K ATPase
Na channel blockers: help block the Na-K ATPase |
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What effect does metabolic acidosis have on K?
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Increased ICF H+ increases ECF K+
Principal cell ICF K is decreased->decreases K secretion Intracellular acidosis also inhibits the Na-K aTPase Metabolic acidosis-->hyperkalemia & decreased K secretion |
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What effect does metabolic alkalosis have on K?
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Decreased intracellular protons-->increased intracellular K
Stimulates Na-K ATPase & luminal K channels Increased K secretion & hypokalemia |
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Describe body distribution of water.
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60% of body weight is water
40% of this 60% is ICF 20% of this 60% is ECF 15% is interstitial 5% is plasma |
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What are the 3 effectors that control renin secretion from granular cells of the afferent arteriole?
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1. Intrarenal baroreceptors: granular cells deform in response to decreased BP & release renin
2. Sympathetic nerve stimulation increases renin secretion 3. MD: low salt flow-->increases renin secretion |
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What nephron segment is responsible for most of pressure natriuresis?
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Proximal tubule
Na-H antiporters are removed from apical membrane Na-K ATPase activity decreases on basolateral membrane |
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What does tubuloglomerular feedback do?
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Blunts extreme changes in RBF & GFR via the macula densa
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What does autoregulation do?
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Blunts extreme changes in RBF & GFR via prostaglandin release
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What does glomulerotubular balance do?
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Blunts extreme changes in Na/water excretion caused by GFR changes
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What are the effects of natriuretic peptides?
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Dilation of afferent arterioles
Inhibition of renin secretion & ATII action Inhibition of Na reabsorption in the distal tubule |
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How does ADH work?
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Binds G-linked protein receptor to increase cAMP-->increased aquaporin 2 in apical membrane
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What is responsible for the Tm of glucose?
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SGLT (apical glucose transporter)
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Where is salt & water handling separated?
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Loop of Henle
Descending limb=water reabsorption Ascending limb=salt reabsorption DCT=salt reabsorption CD: both |
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What secretes ADH?
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pituitary
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Starling force equation for GFR?
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GFR=Kf x NFP
GFR=Kf(Pgc-oncotic pressure(gc)-Pt) |
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Equation for excretion?
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Ex=(Ux)*V
Ux=urine concentration of x V=volume of urine |
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Equation for clearance?
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Cx=(Ex)/Px
Px=plasma concentration of x Ex=(Ux)*V |
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Equation for filtered load?
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FLx=GFR*(Px)
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What is clearance of PAH a good estimation of?
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RPF
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How accurate is PAH as an estimate of RPF?
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PAH over estimates RPF slightly d/t secretion of PAH
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Relationship between RBF & RPF?
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RPF=RBF/(1-Hct)
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What does inulin clearance estimate?
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GFR
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What is the fractional excretion of a substance?
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FEx=(Ux/Px)/(Uin/Pin)
FEx=Cx/Cin |
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What does an FE>1 (or 100%) indicate?
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Net secretion occurred
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What does creatinine clearance estimate and how does in do so?
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Cr=(Ucr*V)/Pcr=GFR
Overestimates by 10-20% Pcr is inversely proportional to GFR |
