Why pH and PCO2 decrease when diarrhoea and vomiting?

During diarrhea and vomiting, the body loses significant amounts of bicarbonate (HCO3-) and carbon dioxide (CO2), leading to a decrease in pH and PCO2. Diarrhea often results in the loss of alkaline fluids, which can cause metabolic acidosis, while vomiting expels stomach acid (HCl), further disrupting the acid-base balance. The decrease in CO2 is due to the loss of carbonic acid as CO2 is expelled, contributing to respiratory alkalosis in some cases. Overall, these processes disturb the normal acid-base equilibrium in the body.