Renal 9 urea, bicarb, buffers

Question 1

No- it is dependent on the development of a favorable concentration gradent and isabsorbed through the paracellular path. 50% is reabsorbed in the porximal convoluted tubule

Answer 1

urea, bicarbonate, and hydrogen

Question 2

urea transporters

Answer 2

urea, bicarbonate, and hydrogen

Question 3

critiacal osmol in the medullary interstitium

Answer 3

urea, bicarbonate, and hydrogen

Question 4

increased nitrogen in the blood

Answer 4

urea, bicarbonate, and hydrogen

Question 5

1.) Decreased GFR (urea production > urea secretion) 2.) elevated urea production (high protien diet, steroid therapy) 3.) Excessive urea reabsorption in PT (ex: hypovolemia)

Answer 5

urea, bicarbonate, and hydrogen

Question 6

term typically used to describe pathological increases in urea

Answer 6

urea, bicarbonate, and hydrogen

Question 7

Can occur in hypovolemic states: GFR falls leading to an increase in plasma creat but there is an increase in reabsorption of Na, other solutes, and water in the proximal tubule die to increased sympathetix activity and increased angiotensin II. BUN increases due to increased GFR and enhanced reabsorption of urea seconday to increased Na and water (development of a more favorable concentration gradient) The Bun: Creat is >20:1 indicating the problem is prerenal

Answer 7

urea, bicarbonate, and hydrogen

Question 8

GFR falls and there is an increase in BUN and Creat but the ratio remins 10:1

Answer 8

urea, bicarbonate, and hydrogen

Question 9

both passively (through paracellular route) and actively through the urea transporter

Answer 9

urea, bicarbonate, and hydrogen

Question 10

1.) increases the permeability to water and urea 2.) stimulates the urea transoprter activity in the medullary collecting duct

Answer 10

urea, bicarbonate, and hydrogen

Question 11

1.) must excrete an amount of H equal to the daily production of nonvolatile acids 2.) Must prevent the loss of HCO3 in the urine

Answer 11

urea, bicarbonate, and hydrogen

Question 12

CO2 is blown off during respiration (rate of ventilation determines areterial PCO2)

Answer 12

urea, bicarbonate, and hydrogen

Question 13

Active process that moves H across the luminal membane into the tubule: H is produced by the reaction between CO2 and water in the lumen, it travels through NHE3 (H transpoter) across the luminal membrane into the lumen(Na moves down its gradient causig secretion of H) . Requires a proton acceptor in the tubular fluid

Answer 13

urea, bicarbonate, and hydrogen

Question 14

For every proton that gets secreted a bicarbonate gets reabsorbed

Answer 14

urea, bicarbonate, and hydrogen

Question 15

H-ATPase pump in the luminal membrane of intercalated cells (there also appears to be a K-H-ATPase in the luinal membrane)

Answer 15

urea, bicarbonate, and hydrogen

Question 16

large lumen negative potential generated by Na reapsorption by principle cells - Coupling between H secretion and Na reabsorption

Answer 16

urea, bicarbonate, and hydrogen

Question 17

aldosterone stimulates Na reabsorption and therefore increased H secretion and K secretion in intercalated cells

Answer 17

urea, bicarbonate, and hydrogen

Question 18

H+ is derived pricipally from the hydration of CO2

Answer 18

urea, bicarbonate, and hydrogen

Question 19

Strong correlation: as PCO2 increase it causes an increase in H secretion

Answer 19

urea, bicarbonate, and hydrogen

Question 20

Hydrogen secretion

Answer 20

urea, bicarbonate, and hydrogen

Question 21

4.5 - after this net secretion ceases

Answer 21

urea, bicarbonate, and hydrogen

Question 22

without proton acceptors secretion would cause a rapid fall in urine pH (due to increased H) and secretion would cease due to back leak of H from the lumen through the tubule and the low lumen pH would inhibit the ATP dependent proton pump. Withough acceptors we wouldnt be able to excrete more than 32 umol H/day (with them we excrete 100,000 umol/day)

Answer 22

urea, bicarbonate, and hydrogen

Question 23

Bicarbonate (HCO3) - the reaction between secreted H with bicarb normally acomplishes the reabsorption of the entired filtered load of HCO3- (why? Because addition of a hydrogen would allow it to cross the membrane and be reabsorbed )

Answer 23

urea, bicarbonate, and hydrogen

Question 24

90% reabsorbed in the proximal tubule ( normally the urine is esentially bicarbonate free)

Answer 24

urea, bicarbonate, and hydrogen

Question 25

Na reabsorption via H+ secretion

Answer 25

urea, bicarbonate, and hydrogen

Question 26

1.) one Na enters the cell ( Na-H antitransporter) 2.) one HCO3 dissappears from the tubular filtrate 3.) one HCO3 is produced in the cell and reabsorbed (due to CO2 that enters the cell) IN OTHER WORDS: Na enters the cell and H moves into the tubular lumen where it interacts with bicarbonate in the presnce of carbonic anhydrase to form CO2 and H20 (this is the step where bicard disappears) Co2 is then allowed to move into the tubular cel where it interacts to create a bicarbonate that then gets reabsorbed (the HCO3 that is reabsorbed is NOT the same one that was originally in the tubular filtrate

Answer 26

urea, bicarbonate, and hydrogen

Question 27

present in within the cells and in the brush border of the luminal sufrace of the tubule. Catalyzes the hydration of CO2

Answer 27

urea, bicarbonate, and hydrogen

Question 28

No Na-H exchanger - relpaced by H-ATPase and H-K ATPase

Answer 28

urea, bicarbonate, and hydrogen

Question 29

Na-H exchanger

Answer 29

urea, bicarbonate, and hydrogen

Question 30

not a true transport maximun (because there isnt a transporter) The transport maximum is really a measure of the capacity to secrete H+. Under normal conditions HCO3 is just slightly BELOW the renal threshold

Answer 30

urea, bicarbonate, and hydrogen

Question 31

phosphate

Answer 31

urea, bicarbonate, and hydrogen

Question 32

1.) excrete 50-100 mEq of acid in the urine as titratable acid and NH4 each day 2.) produce an equal amount of NEW BICARBONATE in the tubular cells and deliver it to the body fluids

Answer 32

urea, bicarbonate, and hydrogen

Question 33

these reactions generally occur after most of the major urinary base (HCO3) has been removed from the filtrate. For each mole of H that reacts with NH3 or anouther base in the tubular fluid, one mole of NEW HCO3 is geneated and restored to the body fluid and one mole of H is eliminated in the urine as a nondissociated acid

Answer 33

urea, bicarbonate, and hydrogen

Question 34

they significantly increase the amount of H that can be secreted while also retoring plasma HCO3 levels

Answer 34

urea, bicarbonate, and hydrogen

Question 35

it gets largely used up before the minumum urinary pH is achieved (4.5) because its pKa is 6.8 - However, bases with lower pKa can then take over to accept protons

Answer 35

urea, bicarbonate, and hydrogen

Question 36

equal number of acid and base

Answer 36

urea, bicarbonate, and hydrogen

Question 37

phosphate (HPO4), urate, creatine, b-hydroxybutyrate (diabetic ketoacidosis), acetoacetat (diabetic ketoacidosis) lactate

Answer 37

urea, bicarbonate, and hydrogen

Question 38

they are only present in small numbers (or not at all)) and the pHa for some are unfavorable for protonation within the normal range of urinary pH

Answer 38

urea, bicarbonate, and hydrogen

Question 39

NH3

Answer 39

urea, bicarbonate, and hydrogen

Question 40

synthysized in tubular cells from glutamine (get 2 NH3 per glutamine) Secreted as NH3 (or NH4+) by all segments of the nephron. NH3 is lipid soluble and secreted by passive diffusion (NH4+ is diffusion trapped)

Answer 40

urea, bicarbonate, and hydrogen

Question 41

allows for the continued secretion in an cid urine

Answer 41

urea, bicarbonate, and hydrogen

Question 42

new HCO3 = titratable acid + NH4

Answer 42

urea, bicarbonate, and hydrogen

Question 43

1.) Availability of urinary base (H+ acceptors) 2.) Changes in aretrial PCO2 (increase PCO2 = Increased H secretion) 3.) Aldosterone excess (can cause hyokalemia or metabilic alkylosis) or deficit (hyperkalemia and metabolic acidosis) 4.) Hyperkalemia (K-H exchange) 5.) Increased Na delivery to the distal nephon (ex: over use of loop or thiazide diuretics - enhanced Na reabsorption leads to H secretion) 6.) Renal tubular acidosis

Answer 43

urea, bicarbonate, and hydrogen