Buffer action in blood

The pH of blood in a healthy human being varies from 7.37 to 7.43. There are two buffer systems that help maintain the pH of blood relatively constant one arising from a carbonic acid/bicarbonate (hydrogencarbonate) ion equilibrium and another involving protonated and deprotonated forms of hemoglobin. 

Carbonic acid forms in blood from the reaction between water and CO2 gas, which comes from inhaled air and is also a by-product of metabolism (Case 

In red blood cells, this reaction is catalyzed by the enzyme carbonic anhydrase. Aqueous carbonic acid then deprotonates to form bicarbonate (hydrogencarbonate) ion  

The condition known as alkalosis occurs when the pH of blood rises above about 7.45. Respiratory alkalosis is caused by hyperventilation, or excessive respiration. The simplest remedy consists of breathing into a paper bag in order to incresise the levels of inhcded CO2. Metabolic alkalosis may result from illness, poisoning, repeated vomiting, md overuse of diuretics. The body may compensate for the incrccise in the pH of blood by decreasing the rate of respiration. 

Acidosis occurs when the pH of blood falls below about 7.35. In respiratory acidosis, impaired respiration increases the concentration of dissolved CO2 and lowers the blood s pH. The condition is common in victims of smoke inhalation and patients with asthma, pneumonia, and emphysema. The most efficient treatment consists of placing the patient in a ventilator. Metabolic acidosis is caused by the release of large amounts of lactic acid or other acidic by-products of metabolism (Case study 43), which react with bicarbonate ion to form carbonic acid, thus lowering the blood s pH. The condition is common in patients with diabetes and severe burns. 

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