A decreased serum pH causes a condition known as:

Choice A reason: Metabolic alkalosis is a condition where the pH and the HCO3- are both elevated, indicating a loss of acids or a gain of bases in the body. This is not the case for this patient, as his HCO3- is within the normal range of 22 to 26 mEq/L.

Choice B reason: Respiratory acidosis is a condition where the pH and the PaCO2 are both low, indicating a retention of carbon dioxide in the lungs due to hypoventilation. This is not the case for this patient, as his pH is high and his PaCO2 is low.

Choice C reason: Respiratory alkalosis is a condition where the pH and the PaCO2 are both high, indicating a loss of carbon dioxide in the lungs due to hyperventilation. This is the case for this patient, as his pH is above the normal range of 7.35 to 7.45 and his PaCO2 is below the normal range of 35 to 45 mm Hg. This condition is uncompensated, as his HCO3- is within the normal range and has not changed to counteract the pH imbalance.

Choice D reason: Metabolic acidosis is a condition where the pH and the HCO3- are both low, indicating a gain of acids or a loss of bases in the body. This is not the case for this patient, as his pH is high and his HCO3- is within the normal range.

Choice A reason: This is incorrect because intracellular fluid is greater than extracellular fluid in a hypertonic state, not an isotonic state. A hypertonic state is when the solute concentration of the extracellular fluid is higher than the intracellular fluid, which causes water to move out of the cells and shrink them.

Choice B reason: This is incorrect because extracellular fluid is less than intracellular fluid in a hypotonic state, not an isotonic state. A hypotonic state is when the solute concentration of the extracellular fluid is lower than the intracellular fluid, which causes water to move into the cells and swell them.

Choice C reason: This is correct because intracellular and extracellular fluid is equal in an isotonic state. An isotonic state is when the solute concentration of the extracellular fluid is the same as the intracellular fluid, which causes no net movement of water across the cell membrane.

Choice D reason: This is incorrect because interstitial fluid is less than the transcellular fluid in a situation of fluid imbalance, not an isotonic state. Interstitial fluid is the fluid that surrounds the cells, while transcellular fluid is the fluid that is contained in specialized cavities, such as cerebrospinal fluid, synovial fluid, or pleural fluid. The amount of transcellular fluid is normally very small compared to the interstitial fluid, but it can increase in certain conditions, such as edema, ascites, or hydrocephalus.