L8 Acid Base Balance Flashcards
Normal body pH
- 35-7.45
6. 8-7.8 to stay alive
Lowest possible pH for urin
4.4
Buffers for urine
Phosphate (endogenous) (used first)
Ammonium (produced)
Forms of excreted acid
NH4+ (non-titratable)
H+ (titratable)
HPO4-2 (titratable)
Typical method of renal regulation of body pH
Reabsorb all and produce more HCO3-
Produces acidic urine, alkaline body
How does HCO3 reabsorption work?
H2O and CO2 form H2CO3 in cell
H2CO3 splits to HCO3 (into blood) and H(combines with HCO3 of urine)
HCO3 reabsorption
Locations
80 percent in proximal tubule
Some in Thick ascending
Rest of it in distal and collecting thru intercalated cell
What happens if the body takes in ammonium?
It would be converted into urea and produce H (increasing acidity)(We produce it to decrease acidity)
How is NH4+ produced
Metabolism of glutamine in proximal tubules (glutamine absorbed, split into NH4 and HCO3, NH4 into urine, HCO3 into blood)
Diffusion trapping
NH4+ leaving the proximal tubule is reabsorbed in ascending limb where NH4+ substitutes for K in Na/K/2Cl symport. Goes into equilibrium with NH3.
NH4 trapped in interstitial fluid
NH3 diffuses into lumen, gets protonated, trapped in lumen and excreted
Hypocalcemia vs hypercalcemia effects
Hypo: Increases excitiability of neural and muscle tissue
Hyper: Cardiac arrhythmia and disorientation
Plasma pH and Ca
Decrease pH leads to increase Ca
Increase in pH leads to decreased Ca
Calcium sensing receptor locations
Parathyroid
Thyroid parafollicular cells
Proximal tubule
Calcium reabsorption in proximal tubule
Proximal: mostly paracellular transport
Thick ascending: transcellular, paracelluar
Distal: transellular (regulated by PTH)
