Questions: What are the causes of metabolic alkalosis? Select the correct answer below: Too much CO2 is eliminated, dropping the CO2 pressure below 38 torr and resulting in a rise in blood pH. This can be caused by hyperventilation, fever, excessive exercise, or reactions to certain drugs. The body eliminates too much acid or produces too much base for the renal system to compensate, resulting in a rise in blood pH. Breathing difficulty or lung problems that reduce the ability to remove CO2, resulting in a CO2 pressure over 42 torr, so acidic protons are not removed and the pH drops. Changes in the H+ or HCO3- concentrations that result in the pH dropping. It can be brought on by diabetes, kidney disease, diarrhea or vomiting, or inadequate oxygen.

The answer is the second one: The body eliminates too much acid or produces too much base for the renal system to compensate, resulting in a rise in blood pH.

Explanation for each option:

1. Too much $\mathrm{CO}_{2}$ is eliminated, dropping the $\mathrm{CO}_{2}$ pressure below 38 torr and resulting in a rise in blood pH. This can be caused by hyperventilation, fever, excessive exercise, or reactions to certain drugs.

   • This describes respiratory alkalosis, not metabolic alkalosis. Respiratory alkalosis occurs when there is excessive elimination of $\mathrm{CO}_{2}$, leading to a decrease in $\mathrm{CO}_{2}$ pressure and an increase in blood pH.

2. The body eliminates too much acid or produces too much base for the renal system to compensate, resulting in a rise in blood pH.

   • This is the correct description of metabolic alkalosis. Metabolic alkalosis occurs when there is an excess loss of acid (e.g., through vomiting) or an overproduction of base (e.g., from excessive intake of bicarbonate), leading to an increase in blood pH.

3. Breathing difficulty or lung problems that reduce the ability to remove $\mathrm{CO}_{2}$, resulting in a $\mathrm{CO}_{2}$ pressure over 42 torr, so acidic protons are not removed and the pH drops.

   • This describes respiratory acidosis, not metabolic alkalosis. Respiratory acidosis occurs when there is impaired removal of $\mathrm{CO}_{2}$, leading to an increase in $\mathrm{CO}_{2}$ pressure and a decrease in blood pH.

4. Changes in the $\mathrm{H}^{+}$ or $\mathrm{HCO}_{3}^{-}$ concentrations that result in the pH dropping. It can be brought on by diabetes, kidney disease, diarrhea or vomiting, or inadequate oxygen.

   • This describes metabolic acidosis, not metabolic alkalosis. Metabolic acidosis occurs when there is an increase in $\mathrm{H}^{+}$ or a decrease in $\mathrm{HCO}_{3}^{-}$, leading to a decrease in blood pH.

Summary: Metabolic alkalosis is caused by the body eliminating too much acid or producing too much base for the renal system to compensate, resulting in a rise in blood pH.