lungs and kidneys function to maintain the PH of
blood plasma within a normal range
the lungs regulate concentration of co2(respiratory )
normal blood plasma PH is 7.35-7.45
this means that the concentration in
plasma blood equals 10-7.4 molar
these H+ ions are produced due to dissociation
of H2CO3 into H+ and HCO-3.
N.B: H2co3
is a volatile acid but lactic acid ,fatty acids and ketone bodies are
non-volatile acids.
H+
produced by non-volatile acids don't affect PH because it's buffered by HCO-3
HCO-3 + H+ --> H2CO3
And so doesn't affect PH of blood plasma,
when HCO-3 is depleted , H+ concentration will increase and so PH will
decrease leading to acidity.
Acidosis doesn't mean acidic (remember acidic
means below PH of 7 but in extreme cases of acidosis PH reaches 7.2).
*Why loss of HCO-3 increase acidity?
According to this equation:
HCO-3 + H+ --> H2CO3
Loss of HCO-3 shift the reaction to the left and so leading
to increasing H+ which
in turn lead to decreasing PH à increase acidity
N.B: H+ can not be buffered due to loss of HCO-3.
*Clinical note:
In case of Diarrhea HCO-3(secreted within the pancreatic juice) is lost leading to
increasing acidity.
*why does increasing HCO-3 lead to alkalosis?
HCO-3 + H+ --> H2CO3
An increase in HCO-3 shift the reaction to the right leading to a decrease in the H+
concentration and thus increasing PH which means alkalosis.
