Acid-Base Regulation (Week 11) Flashcards
(66 cards)
pH that is considered acidemia
< 7.4
pH that is considered alkalemia
pH > 7.4
major organs for acid-base regulation
kidney and liver
how does a buffer interact with H+ and how does it affect pH
when H+ is added to a system with a buffer the H+ combines with the buffer; instead of H+ concentration increasing a new compoun is formed and the pH isn’t changed
role of kidneya and lung in bicarbonate buffer system
lungs handle CO2 and kidney handles bicarbonate; if one of these organs isn’t working well then the equation shifts to the side that is functioning

two major acid-base functions of kidney
- reabsorb bicarbonate
- excrete H+
how much bicarbonate is filtered/reabsorped in kidney?
bicaronate is freely filtered (small ion); 100% is reaborbed normally
how is bicarbonate reabsorbed?
bicarbonate combines with H+ and is formed into H20 + CO2 by carbonic anhydrase; crosses apical membrane; bicarbonate reformed in cell and transported across basolateral membrane
urine buffers
phosphate (fixed buffer) and ammonia (regulated buffer)
ammonia production compared to body acid
increased acid in body => increase ammonia production
factors that increase renal H+ excretion (4)
- decrease extracellular pH (increase H+ conc)
- decreased plasma K+
- decreased ECV
- increased aldosterone
kidney response to metabolic acidosis and where it occurs
- proximal tubule cells makes more ammonia; increase Na+/H+ activity
- ATP activity – secreting more H+ to lumen via increase H+ ATPase activity
- Collecting Tubule; Intercalated Cell Type A
kidney response to metabolic alkalosis and where it occurs
Intercalated Cell Type B in collecting tubule
puts bicarbonate into urine and reabsorbs H+
when are intercalated cell tyle B cells activated?
only in metabolic alkalosis; are otherwise dormant
affect of ECV on acid secretion by kidney
decreased ECV increases RAAS
Na+ reabsorbed and H+ secreted in process
increased H+ excretion
summary: decreased ECV can result in metabolic alkalosis
aldosterone affect on H+ excretion
aldosterone induces metabolic alkalosis via increase H+ excretion
- Na+ reabsorbed as H+/K+ excreted
- H+-ATPase pump gets stimulated
- HCO3- /Cl- pump activated
what is the relationship between plasma K+ and renal H+ excretion?
decreased plasma potassium = K+ move out of cells and H+ move into cells
leads to intracellular acidosis in kidney causing a response that leads to metanolic alkalosis
decreased K+ = metabolic alkalosis
hyperkalemia and plasma H+
hyperkalemia causes metabolic acidosis (and metabolic acidosis causes hyperkalemia)
bicarbonate buffer system imbalance in metabolic acidosis
decreased HCO3-
bicarbonate buffer system imbalance in metabolic alkalosis
increased HCO3-
bicarbonate buffer system imbalance in respiratory acidosis
increased PCO2
bicarbonate buffer system imbalance in respiratory alkalosis
decrased PCO2
respiratory compensation for metabolic acidosis
hyperventilation (decreased PCO2)
trying to increase the pH to keep it at 7.4
If CO2 levels high, kidney will compensate by increasing bicarbonate in system
causes of low bicarbonate (metabolic acidosis)
- bicarbonate loss (renal, diarrhea)
- consumption of HCO3- (increased acid in body)
- failure of regeneration (renal failure, RTA distal)




