Acid-base balance. Buffering of hydrogen ions in body fluids – buffer systems. Flashcards
functions of buffers
to maintain correct pH in blood within optimal range 7.36-7.44
for optimal cellular function
buffer system 1
carbonic acid buffer system
at equilibrium = H2CO3- ↔ H+ (into tubular fluid) and HCO3− (into renal blood)
buffer system 2
phosphate buffer system
H2PO4- ⇌ H+ and HPO42−
- dihydrogen phosphate = weak acid
- hydrogen phosphate = conjugate base
location - intracellular fluid/ renal tubular fluid
buffer system - 3
hemoglobin buffer system
Hb + H+ ↔ HHb (reducing H+ in blood to control pH)
buffer system 4
protein buffer
amino groups accept H+ forming NH3+
carboxyl groups donate H+ forming COO-
buffering mechanism - 1
respiratory compensation
during acidosis
- less breathing = less co2 out = more co2 in = more carbonic acid in (base)
during alkolosis
- more breathing = more co2 out = less co2 in = less carbonic acid (base)
Respiratory Regulation - 1
central chemoreceptor
Respiratory Regulation - 2
peripheral chemoreceptor
Respiratory Regulation - 3
hypercapnia vs hypocapnia
buffering mechanism - 2
renal compensation
acidosis
- more H+ released into urine
- more HCO3- reabsorbed into blood
alkolosis
- less H+ released into urine
- less HCO3- reabsorbed back into blood
Renal control of acid-base balance - 1
- bicarbonates function to buffer blood by neutralising excess acids
Renal control of acid-base balance - 2
DCT / CD = active secretion of H+ directly into lumen = acidification of urine
Renal control of acid-base balance - 3
kidneys can metabolise glutamine into ammonium + bicarbonate
ammonium secreted into tubular fluid
bicarbonate is reabsorbed
Renal control of acid-base balance - 4
angiotenin II = activates sodium-hydrogen exchanger in PCT
- reabsorption of HCO3-
- secretion of H+
