Human blood has a narrow Ph range of `7.3-7.4`, which must be maintained for methabolic processes to
Channel: Doubtnut
Date: 2020-04-19

Human blood has a narrow Ph range of `7.3-7.4`, which must be maintained for methabolic processes to function properly. To keep the Ph in this range requires a delicate balance between the concentration of the conjugate acid-base pairs making upto the buffer system. The main buffer is a carbonic acid/ hydrogencarbonate system, which involves the following three equilibria.   `CO_(2)(g)hArrCO_(2)(aq)`   `CO_(2)(aq)+H_(2)O(l)hArrH_(2)CO_(3)(aq)`   `H_(2)CO(aq)+H_(2)O(l)hArrHCO_(3)^(-)(aq)+H_(3)O^(+)(aq)`   Carbonic acid `(H_(2)CO_(3))` is a weak acid and `HCO_(3)^(-)`(aq) is its conjugate base. At the temperature of the human body, the `pK_(a)` for carbonic acid is 6.4 However, the normal concentration of `CO_(2)(g)` in the lungs maintanis a ratio of `HCO_(3)^(-)(aq)//H_(2)CO_(3)(aq)` in blood plasma of about `8:1`.   The carbonic acid concentration in the bloos is largely controlled by breathing and respiration. Hydrogencarbonate ion concentration is largely controlled by excreation in urine.   If blood pH rises above `7.4`, a potentially life-threatening conditon called  alkalosis can result. This can happen in patients who are hyperventilating from severse anxiety, or in climbers suffereing from oxygen deficency at high altitude. (Given: log 2=0.3)   Calculate pH of blood at the temperature of the human body.