Final answer:
Severe vomiting causes metabolic alkalosis by expelling stomach acid in the form of hydrochloric acid, which includes hydrogen (H+) and chloride (Cl-) ions. The loss of acidic hydrogen ions raises the pH, creating an alkaline condition. Medications such as diuretics and antacids can also contribute to this imbalance by causing the body to retain more bicarbonate or lose potassium.
Step-by-step explanation:
Metabolic alkalosis occurs when severe vomiting causes a loss of hydrogen and chloride ions, which are components of hydrochloric acid (HCl) in the gastric juices. The reduction in hydrogen ions, which are acidic, tilts the balance towards a more alkaline state. As the chloride ions are lost alongside hydrogen, this can impede the kidneys' ability to excrete bicarbonate, given that chloride is needed for bicarbonate exchange in the renal tubule. Hence, bicarbonate accumulates, contributing to alkalosis.
Several medications can also induce metabolic alkalosis, such as diuretics that enhance the loss of potassium ions and antacids when consumed in large amounts. A primary bicarbonate excess characterizes metabolic alkalosis, elevating the blood pH above the normal range. Potassium loss – often seen with diuretic use – can also exacerbate alkalosis since the body may exchange excess hydrogen ions for the lost potassium, reducing acidity.