Question

Primary changes in Acid Base disorders are:

• A. Metabolic acidosis: decreased plasma bicarbonate and Respiratory acidosis: decreased $P_{\text{CO}_{2}}$ \
• B. Metabolic alkalosis: decreased plasma bicarbonate and Respiratory alkalosis: decreased $P_{\text{CO}_{2}}$ \
• C. Metabolic acidosis: decreased plasma bicarbonate and Respiratory alkalosis: decreased $P_{\text{CO}_{2}}$ \
• D. Respiratory alkalosis: decreased $P_{\text{CO}_{2}}$ and Respiratory acidosis: decreased $P_{\text{CO}_{2}}$

Hint:

Metabolic concerns Bicarbonate ($\text{HCO}_{3}^{-}$) changes in the same direction as pH. Respiratory concerns $P_{\text{CO}_{2}}$ changes in the opposite direction of pH.

Answer 1

The Correct Option is C

Step 1: Concept Acid-base disorders are classified as metabolic or respiratory depending on the primary cause and the changing parameters in the blood chemistry.

Step 2: Meaning Acidosis involves processes that lower blood pH, whereas alkalosis involves processes that raise blood pH. Primary metabolic disorders primarily impact bicarbonate concentrations ($\text{HCO}_{3}^{-}$), while respiratory disorders primarily change the partial pressure of carbon dioxide ($P_{\text{CO}_{2}}$).

Step 3: Analysis * Statement A: Metabolic acidosis is correctly identified by a primary drop in plasma bicarbonate concentration. * Statement B: Metabolic alkalosis results in an increase, not a decrease, in plasma bicarbonate. * Statement C: Respiratory alkalosis involves hyperventilation which leads to a primary decrease in plasma $P_{\text{CO}_{2}}$. * Statement D: Respiratory acidosis is characterized by an increase, not a decrease, in plasma $P_{\text{CO}_{2}}$ due to carbon dioxide retention. Therefore, statements A and C are the only correct descriptions of primary changes.

Step 4: Conclusion Hence, the correct option matching both A and C is chosen. Final Answer: (C)