Renal Control Of Acid Base Disturbances Flashcards
What are the volatile sources (CO2 derived) of metabolic acids?
Glucose + O2 —> H+ and HCO3-
Fat + O2 —> H+ and HCO3-
Eliminated via the lungs
What are the non-volatile (fixed) metabolic acid sources?
Glucose —> H+ and lactate (anaerobic)
Cysteine + O2 —> H+ and sulfate
Phosphoprotein + O2 —> H+ and phosphate
Eliminated via the kidneys
What are the body’s buffer systems?
Bicarbonate, Hb, phosphate, and plasma proteins
If acidemia is present what will the ICF take in?
H+ which will be buffered by raising ECF [K+]
If alkalemia is present the ICF will donate what?
H+ which will be buffers by lowering ECF [K+]
What is the Henderson-Hasselbach equation?
ph = 6.1 + log([HCO3]/[H2CO3])
H2CO3 can be determined by 0.03xPCO2
Describe the renal reabsorption of bicarbonate
Mostly reabsorbed in the PT
1 mEq/L excreted per day
Very minuscule clearance value (bc most of it is reabsorbed)
How is “new” bicarbonate generated?
During the process of urinary acidification when secreted H+ is buffered by NH3 —> NH4, phosphate, etc, for excretion while bicarbonate is reabsorbed
What is net acid excretion (NAE)?
(UNH4 x V) + (UTA x V) - (UHCO3 x V)
What must NAE equal each day in order to maintain acid base balance?
Must equal nonvolatile acid production
What are titratable acids (TA)?
Salts of primarily phosphate but other constituents of urine such as creatinine do contribute
Accounts for 1/3 of NAE
What is responsible for 2/3 NAE?
Ammonium (NH4) synthesis and secretion
Body can easily make as much as it needs unlike with TA