Body fluid normally have a PH of 7.35 – 7.45. The chief acid regulating from Metabolism is H2CO3 which is formed by a combination of CO2 + H2O. The combination is promoted by carbonic anhydrase with in the cells. In addition to the carbolic acid, cellular activity produces a substantial quantity of strong acid.
Acids must be rapidly neutralized or weakened by chemical reaction.
There must be a constant elimination of them from the body. Carbolic acid is removed by lungs by eliminating carbon dioxide.
Control Mechanism of body PH
The optimum PH of the body fluid is maintained by:
1. acid-base buffer system
2. respiratory system regulation
3. kidney regulation
Buffers are substances, which tends to stabilize or maintain the constancy of the PH of a solution when an acid or a base is added to it.
Example: HCl + NaCO3 > H2CO3 + HaCl
They do this by rapidly converting a strong acid or base to a weaker
one, which does not dissociate as rapidly.
Strong base NaOH + HCO3 gives H2ONaCO3
Example of Buffering System:
A) Bicarbonate Buffering System
B) Phosphate Buffering System
Respiratory Regulation of Acid-Base Balance
Carbondioxide is constantly produced in cellular metabolism and diffuses from the cells into the blood and crythrocyte, and as a result CO2 is in greater concentration in the blood. When it enters pulmonary capillaries than in the air in alveoli of the lungs.
Kidney Regulation
The kidneys play an important role in maintaining acid base balance by execration of H+ and forming hydrogen carbonate.
The cell of the distal tubules is sensitive to the changes in the PH.
Test for acid base balance
1. Blood gas: O2 and CO2 are checked
- H+ concentration in arterial blood is checked
- PH also determined
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