MCAT Question A Day - 8/12/14 - Answer!
Alkalosis is increased blood pH resulting in a leftward shift of the oxy hemoglobin dissociation curve. Which of the following might cause alkalosis?
A. hypoventilation
B. hyperventilation
C. breathing into a paper bag
D. adrenal steroid insufficiency
B is correct. Hyperventilation results in loss of CO2, leading to lower concentrations of carbonic acid in the blood, and an increase in pH. Hypoventilation would result in the reverse. Breathing into a bag would increase the CO2 content of the air and lead to acidosis. Excess aldosterone may lead to metabolic alkalosis due to hydrogen ion exchange in the kidney.
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B is correct. Hyperventilation results in loss of CO2, leading to lower concentrations of carbonic acid in the blood, and an increase in pH. Hypoventilation would result in the reverse. Breathing into a bag would increase the CO2 content of the air and lead to acidosis. Excess aldosterone may lead to metabolic alkalosis due to hydrogen ion exchange in the kidney.
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