renal 7 Flashcards
What is the normal pH of the blood
7.4
describe how ventilation rate (and thus PO2) changes with changes in pH
Decreased pH increases ventilation to try and blow off excess CO2
define respiratory acidosis
not enough CO2 blown off
- lowered breathing rate
define respiratory alkalosis
too much CO2 blown off
- increased breathing rate
metabolic acidosis
too acidic
- can’t be eliminated by respiration
metabolic alkalosis
too basic
- can’t be eliminated by respiration
acidemia
process of lowering pH
alkalemia
process of raising pH
how does the kidney compensate for metabolic acidosis or alkalosis
- responds to alkalosis by excreting alkaline urine high in HCO3
- responds to acidosis by excreting acidic urine, and kidney reabsorbs all the bicarbonate
describe the effect of a chemical buffer when a strong acid or strong base is added to a body fluid
- Buffer can reversibly bind H+
- when blood is acidic, buffer binds to H+ as long as buffer is available to keep pH in check
- IF pH is LOW, the buffer releases from H+ to keep the pH in check
where is the bicarbonate buffer system used?
- used in ECF
- HCO3 binds free H+
- catalyzed by carbonic anhydrase
where is the phosphate buffer system used?
- used in urine and ICF
- phosphate is low in ECF
where is the protein buffer system used
- used in ICF, hemoglobin and plasma are buffering agents
- amounts of proteins don’t change in response to stimulus so not part of normal compensatory response
where is ammonia buffer system used?
body’s major adaptive response to acid load
describe bicarbonate reabsorption
- fluid in lumen contains HCO3
- active secretion of H+ into lumen causes HCO3–> H2CO3 and then forms –> CO2 and H20
- CO2 diffuses into renal tubule cell where it combines with H20 to makemore H2CO3 which breaks down into HCO3 and H+
- HCO3 then moves down concentration gradient across basolateral membrane via carrier mediated diffusion
describe how bicarbonate reabsorption can compensate for acidosis
- The H+ secreted becomes H2O which is excreted
- compensates for acidosis by reabsorbing all or most of the HCO3
- opposite compensation for alkalosis
describe phosphate buffering in respiratory acidosis
- secreted H+ binds to available phosphate (NaHPO4-) and is excreted
describe glutamine-NH4+ buffering in severe respiratory acidosis
- If all of the HCO3 is reabsorbed and used up all the phosphate and is STILL ACIDIC… the glutamine-NH4+ system can be used
- IN PROXIMAL TUBULE, glutamine can be metabolized to bicarbonate (which is added to blood) and ammonium ion which is secreted and excreted
