The balance of acids and bases in the blood must remain within a very narrow range. The body has a variety of mechanisms to maintain the proper blood pH. These mechanisms respond quickly to make alkaline blood more acidic and acidic blood more alkaline.
Blood pH
The pH scale ranges from zero to 14, with water neutral with a pH of 7. The strongest possible acid has a pH of 0 and the strongest possible base has a pH of 14. The pH of human blood normally ranges between 7.35 and 7.45. A value below this range is called acidosis, and a value above this range is called alkalosis. Each type of acid-base imbalance may have a metabolic or respiratory cause.
Metabolic Acidosis
Metabolic acidosis is a low pH due to a metabolic cause. It's typically caused by ingesting substances such as wood alcohol, antifreeze or large amounts of aspirin. An abnormal metabolism can also cause metabolic acidosis, which can occur in cases of severe shock, type I diabetes and kidney failure.
Respiratory Acidosis
Respiratory acidosis is a low blood pH due to a respiratory cause. It occurs when the lungs aren't able to adequately expel carbon dioxide. This is most often the result of respiratory diseases such as asthma, chronic bronchitis, pulmonary edema and severe pneumonia. Respiratory acidosis may also be caused by muscular or neurological problems that impair respiration.
Metabolic Alkalosis
Metabolic alkalosis is a high blood pH due to a metabolic cause. It frequently results from the excessive loss of stomach acid. This can occur after prolonged vomiting or when the stomach is suctioned. An excessive loss of potassium or sodium can cause the kidneys to lose their ability to control the body's acid-base balance. Rare cases of metabolic alkalosis may also occur from ingesting large amounts of baking soda.
Respiratory Alkalosis
Respiratory alkalosis is a high blood pH from a respiratory cause. It's the result of hyperventilation, which causes the lungs to expel too much carbon dioxide. This is most commonly due to stress, but it can also be the result of fever, pain and insufficient oxygen in the blood.
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