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Renal 2
Question | Answer |
---|---|
How does urea reabsorption work? | Urea drags water from CD into interstitium. Low water intake leads to ADH increasing activity of apical UT transporters |
Where does urea reabsorption occur? | Collecting duct |
Where does bicarbonate reabsorption occur? | 85%-90% reabsorbed in the PCT 0-5% in the DCT |
How does bicarbonate reabsorption in the PCT work? | Hydrogen leaves the cell via H+ ATPase, and the Na/H+ antiporter Bicarbonate crosses the basolateral side via Na/HCO3- symporter |
How does bicarbonate reabsorption in the DCT work? | H+ secretion by the intercalated cell H+ ATPase HCO3- crosses basolateral membrane via HCO3-/Cl- exchanger |
Explain ammonia formation (NH3) and its role is acid balance | PCT synthesizes NH3 from glutamine. It accepts H+ to form ammonium NH4+ in the tubular fluid. Renal tubules are impermeable to ammonium, so it is excreted |
What is GFR? | Tells you how well your kidneys are filtering |
How is GFR measured? | GFR = UV/P |
Why is inulin used in GFR measurement? | it is not reabsorbed by kidneys or secreted back by peritubular capillaries |
What is involved in the juxtaglomerular apparatus? | Macula densa of DCT, Juxtaglomerular cells, and Extraglomerular mesangial cells |
Explain the tubuloglomerular autoregulation mechanism | Macula densa cells sense the levels of Na in the fluid. It releases prostaglandin which stimulates the hormonal system, and NO, that vasodilates the afferent arteriole |
Explain how the hormonal regulation works | Granular cells are stimulated by prostaglandins and activation of beta 1 receptors. This triggers renin release that produces angiotensin 2 |
What does angiotensin 2 do? | Vasoconstrict efferent, release aldosterone, ADH, increases catecholamine release |
How does the myogenic regulation work? | Blood pressure is monitored. With a drop of BP, calcium channels close, leading to a vasodilation of the afferent. |
How does macula densa cell control vasodila/constriction? | Ca2+ |
Describe the neural mechanism for autoregulation | BP is monitored by baroreceptors that activates the Sympathetic nervous system |
Describe the RAAS system | |
What does aldosterone do? | Acts on principle cells of DCT and CD by upregulating basolateral NaK ATPase. Upregulates ENaCs in CD and colon Stimulate secretion of H+ by H+ ATPase in intercalated cells of cortical CD |
What does ADH do? | Increase transcription of AQP2 by cAMP activation of protein kinase A. Increase Na uptake. Increase Urea uptake in CD by regulating expression of UT. V1 receptor in smooth muscle (vascular) vasoconstriction |
What epithelial cell type can be found in the PCT? | Squamous cuboidal epithelium |
What epithelial cell type can be found in the Ascending loop? | Simple cuboidal epithelium |
What do principle cells do? | Secrete K+ and absorb Na+ |
Plasma concentration of K+ triggers what hormone? | Aldosterone |
What has no effect on GFR? | ADH |
Where is the vasa recta found? | Juxtamedullary nephrons |
What allows urea into the LOH? | UT-B |
Aldosterone targets which cells? | Principle cells in renal CD epithelium |
What does ANP do? | It dilates the afferent and constricts the efferent.Increases blood flow through the vasa recta, which will wash the solutes out of the medullary interstitium, leads to less reabsorption of tubular fluid and increased excretion. Inhibits renin secretion, |
ANP is stimulated by? | Increased cardiac distention, Sympathetic activity, Angiotensin 2 and exercise |
ANP is produced by? | Cardiac myocytes |