acid base 1 Flashcards
What do the kidneys normally excrete and how much?
acid. 1 mEq/kilo
where is bicarb reabsorbed?
80% PT, 15% TAL, 5% CCD, none in urine
what are the apical H/bicarb transporters in PT
H/Na antiporter, H atpase (combines w/ bicarb)
what are the basolateral H/bicarb transporters in PT?
HCO3/Cl antiporter, HCO3/Na symporter
how does H/HCO3 happen in the CT.
alpha and beta intercalated cells. alpha- H/ATPase in apical so secretes acid. Beta- H/ATPase in basal so secretes bicarb via hco3/Cl antiporter
what is the most important transporter in CT?
H atpase
how does ECF volume contraction affect H secretion and where? Aldosterone? hypokalemia? PTH?
increases it in PT. increases in CT. increase in PT.
how does ECF expansion change bicarb reabsorption
inhibits
how does aldosterone affect the distal nephron
stimulates H ATPase in intercalated cells and Na reabsorption (na/H antiporter) (secretion).
what are the two main urine buffers?
ammonia and titratable acid (Hpo4)
how is ammonia formed?
1) NH4+ forms from glutamine in PT and enters tubular fluid 2)NH4+ reabsorbed in LOH 3) NH3 enters CT and gets trapped as NH4+
in non-gap acidosis, how much should Cl change? If it isn’t?
increase 1:1 w/ decrease in bicarb. absence of 1:1 relationship means mixed disorder
Equation for urine AG? interpretation?
(Na+K)-Cl. Use in Acidosis setting. If UAG is very (-) there is NH4 secretion. If it is (+) or close to 0 then it indicates RTA
How is met alk compensated for by kidneys?
^ bicarb absorption from beta intercalated cells.
Tx for met alk w/ hypovolemia
Administer NaCl
DDx of met alk w/ hypokalemia
diuretics, vomiting (has low urine Cl), bartters
what is the henderson hasselbach eq
pH=6.1+log ([HCO3-]/(.03*pCO2))
Compensatory response: Met acid, met alk,
Decrease in pCO2=1.2(delta bicarb), Increase in pCO2=0.6(delta bicarb)
Compensatory response: Resp acid, resp alk
Acute: Increase in bicarb=.1(delta pCO2), chronic: .4(delta pCO2). Acute: decrease in bicarb=.2(delta pCO2), chronic=.5(delta pCO2)
causes of elevated AG acidosis
Methanol, uremia, DKA, Prop glycol, ischemia, Lactic acidosis, Ethanol, salicylates
causes of non elevated AG acidosis
Diarrhea, Ureteral diversion, RTA, Hypocapnia, Acetazolamide, Mineralcorticoid deficiency
Define Saline responsive met alk and causes
Urine Cl<15. Vomiting, NG suction. diuretics
define saline resistant met alk and causes
Urine Cl>20. Hyperaldosteronism, bartter and gitelmans, licorice
what does aspirin cause
AG acidosis w/ resp alkalosis
