Renal BRS questions

What would cause an increase in both GFR and RPF?

Dilation of the afferent arteriole -will increase both GFR (because Pgc is increased) and RPF (because renal vascular resistance is decreased)

To maintain normal H+ balance, total daily excretion of H+ should equal the daily

Fixed acid production plus fixed acid ingestion -total daily production of fixed H+ from catabolism of protons and phospholipids must be matched by sum of excretion of H+ as titratable acids plus NH4+ to maintain acid/base balance

At what site of nephron does the amount of K+ in tubular fluid exceed the amount of filtered K+ in a person on a high K+ diet?

K+ is secreted by late DCT and collecting ducts -affected by dietary K+, a high K+ diet can secrete more K+ into the urine than was originally filtered -K+ is reabsorbed in PT and LOH

Pt with severe diarrhea. pH= 7.25 PCo2= 24 mmHg [bicarb]= 10 mEq/L decreased blood [K+] and normal anion gap What is diagnosis?

Metabolic acidosis -acid pH -decreased bicarb -decreased PCo2 -Diarrhea causes GI loss of bicarb --> acidosis

Which of the following substances has the highest renal clearance?

PAH -both filtered and secreted

At plasma PAH concentrations below the transport maximum (Tm), PAH

PAH concentration in the renal vein is close to zero -Plasma concs > Tm for PAH secretion --> PAH conc in renal vein is nearly zero because the sum of filtration plus secretion removes virtually all PAH from the renal plasma -PAH in renal vein < renal artery: Most PAH entering the kidney is excreted in urine -PAH clearance is greater than Can because PAH is filtered and secreted (Inulin is only filtered)

Secretion of K+ by the distal tubule will be decreased by

spironolactone administration -Distal K+ secretion is decreased by factors that decrease the driving force for passive diffusion of K+ across the luminal membrane -spironolactone=aldosterone antagonist --> reduces K+ secretion

Action of PTH on renal tubule?

stimulation of adenylate cyclase -stimulating AC --> generating cAMP -Major actions of PTH are: inhibition of phosphate reabsorption by PT stimulation of Ca2+ reabsorption in DCT

What causes a decrease in renal Ca2+ clearance?

Thiazide diuretics -increase Ca2+ reabsorption --> decreasing Ca2+ excretion and clearance -PTH increases Ca2+ reabsorption in TAL so lack of PTH will cause an increase in Ca2+ clearance -Furosemide inhibits Na+ reabsorption in TAL -ECF expansion inhibits Na+ reabsorption in PT

What would produce an increase in the reabsorption of isosmotic fluid in the PT?

Increased filtration fraction -larger portion of the renal plasma flow is filtered across the glomerular capillaries -increased flow causes an increase in protein conc and oncotic pressure of the blood leaving the glom caps -increased oncotic pressure in the peritubular capillary blood is a driving force favoring reabsorption in the PT

When the plasma [glucose] is higher than occurs at transport maximum (Tm), the

excretion rate of glucose increases with increasing plasma [glucose] -At concentrations greater than at the transport maximum (Tm) for glucose, the carriers are saturated so that the reabsorption rate no longer matches the filtration rate -difference is excreted in the urine -as plasma [glucose] increases, excretion of glucose increases

A pt with following arterial blood values: pH= 7.52 PCo2= 20 mmHg [bicarb]= 16 mEq/L

he has decreased ionized [Ca2+] in the blood -alkaline pH, low PCo2, low bicarb = consistent with respiratory alkalosis -[H+] is decreased and less H+ bound to neg charged sites on plasma proteins --> more Ca2+ bound to proteins --> ionized [Ca2+] decreases

A person with water deprivation will have a

higher rate of H2O reabsorption in the collecting ducts -higher plasma osmolarity, higher circulating levels of ADH --> will increase the rate of H2O reabsorption in the collecting ducts

What is a cause of metabolic alkalosis?

hyperaldosteronism -incresaed aldosterone levels cause increased H+ secretion by distal tub and increased reabsorption of "new" bicarb

The reabsorption of filtered bicarb

is inhibited by decreases in arterial PCo2 -decreases in arterial PCo2 --> decrease in reabsorption of filtered bicarb by diminishing the supply of H+ in the cell for secretion into the lumen -Reabsorption of bicarb requires CA to convert filtered bicarb to CO2