Final answer:
Metabolic acidosis occurs due to a primary bicarbonate deficiency leading to an excessively acidic blood pH. It can be due to the production of organic acids, intake of acidic substances like aspirin, a decrease in the excretion of hydrogen ions, or loss of bicarbonate through diarrhea. Compensation may occur with a subsequent decrease in pCO2.
Step-by-step explanation:
Metabolic acidosis happens when the blood becomes too acidic (pH below 7.35) due to a deficiency in bicarbonate, also known as primary bicarbonate deficiency. This imbalance is typically caused by an excess presence of organic acids, such as those seen in conditions like diabetic ketoacidosis, or from the intake of substances that can lead to acidosis. For instance, an overdose of aspirin leads to acidosis through the acidity of its metabolite, sulfasalicylic acid. Additionally, strenuous exercise may cause a temporary metabolic acidosis via the accumulation of lactic acid.
Another contributor to metabolic acidosis is uremia, which involves the retention of urea and uric acid. Metabolic acidosis can also be induced through the reduced excretion of hydrogen ions, thereby impeding the conservation of bicarbonate ions, or through excessive loss of bicarbonate ions via the gastrointestinal tract as a result of conditions like diarrhea. It is crucial to understand that while the partial pressure of carbon dioxide (pCO2) might initially remain normal, it typically decreases in cases where compensation occurs, allowing the body to try to restore the proper ratio of bicarbonate and carbonic acid/CO2.