Lena Mason, who has diabetes, is admitted in a stuporous condition. Her blood gases show a pH of 7.33, PaCO2 of 40 mm Hg, and HCO3- of 20 mEq/L. What type of acid-base imbalance does this patient have?

Choice A reason: Diffusion is the process by which small ions such as glucose, oxygen, and carbon dioxide redistribute themselves through semipermeable membranes from areas of higher concentration to areas of lower concentration. This is how these molecules move across the cell membrane and the capillary wall.

Choice B reason: Osmosis is the process by which water moves through semipermeable membranes from areas of lower solute concentration to areas of higher solute concentration. This is how water balance is maintained across the cell membrane and the capillary wall.

Choice C reason: Blood pressure is the force exerted by the blood on the walls of the blood vessels. It is not a process by which small ions redistribute themselves through semipermeable membranes, but rather a factor that influences the movement of fluids and solutes across the capillary wall.

Choice D reason: Rehydration is the process of restoring the fluid balance in the body by drinking fluids or receiving intravenous fluids. It is not a process by which small ions redistribute themselves through semipermeable membranes, but rather a treatment for dehydration.

Choice A reason: This is incorrect because respiratory alkalosis is a condition where the blood pH is higher than the normal range of 7.35 to 7.45, due to hyperventilation, which lowers the carbon dioxide in the blood. Severe diarrhea does not cause hyperventilation, but rather dehydration and electrolyte imbalance.

Choice B reason: This is incorrect because metabolic alkalosis is a condition where the blood pH is higher than the normal range of 7.35 to 7.45, due to a loss of acids or an excess of bases in the body. Severe diarrhea does not cause a loss of acids or an excess of bases, but rather a loss of fluids and bicarbonate, which is a base that buffers the acids in the blood.

Choice C reason: This is correct because metabolic acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to an excess of acids or a loss of bases in the body. Severe diarrhea causes a loss of fluids and bicarbonate, which is a base that buffers the acids in the blood. This leads to an accumulation of acids and a decrease in pH.

Choice D reason: This is incorrect because respiratory acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to impaired gas exchange or hypoventilation, which causes carbon dioxide to accumulate in the blood. Severe diarrhea does not affect the respiratory system directly, but rather the metabolic system.