What is the role of hemoglobin in gas exchange?
Hemoglobin stores oxygen in the lungs for when the demand is increased.
Hemoglobin prevents carbon dioxide from entering into the bloodstream.
Hemoglobin transports oxygen from the lungs to the tissues of the body.
Hemoglobin produces oxygen for increased delivery to the body’s tissues.
The Correct Answer is C
Choice A reason: Hemoglobin does not store oxygen in the lungs; it binds oxygen in the alveoli and releases it in tissues. Oxygen storage is minimal, and myoglobin in muscles serves this role, making this choice incorrect for hemoglobin’s primary function in gas exchange.
Choice B reason: Hemoglobin does not prevent carbon dioxide from entering the bloodstream. It binds carbon dioxide in tissues and transports it to the lungs for exhalation, facilitating gas exchange, not blocking it, making this choice incorrect for hemoglobin’s role.
Choice C reason: Hemoglobin binds oxygen in the lungs, forming oxyhemoglobin, and transports it via red blood cells to body tissues, where it releases oxygen for cellular metabolism. This is its primary role in gas exchange, making this the correct choice.
Choice D reason: Hemoglobin does not produce oxygen; oxygen is inhaled from the environment. Hemoglobin’s role is to transport oxygen, not synthesize it, making this choice incorrect as it misrepresents the physiological function of hemoglobin in gas exchange.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A reason: Prolonged nasogastric suctioning removes gastric acid (HCl), reducing hydrogen ions in the blood, leading to metabolic alkalosis. This is reflected by elevated pH (7.50) and increased HCO3 (28 mEq/L), with normal PaCO2 as the lungs have not yet compensated. This matches the expected acid-base imbalance, making it correct.
Choice B reason: This result shows a slightly acidic pH (7.34) with normal PaCO2 and low HCO3, suggesting metabolic acidosis. Nasogastric suctioning causes loss of acid, not base, so it does not lead to acidosis. This imbalance is inconsistent with the alkalosis expected from gastric acid loss, making it incorrect.
Choice C reason: This result indicates a low pH (7.32) and elevated PaCO2, suggesting respiratory acidosis with partial compensation (normal HCO3). Nasogastric suctioning affects gastric acid, causing metabolic, not respiratory, alkalosis. The respiratory parameters here do not align with the condition’s pathophysiology, making this choice incorrect.
Choice D reason: This result shows an elevated pH (7.46) and low PaCO2, indicating respiratory alkalosis, likely from hyperventilation, with normal HCO3. Nasogastric suctioning causes metabolic alkalosis due to acid loss, not respiratory changes. The low PaCO2 does not fit the expected metabolic profile, making this choice incorrect.
Correct Answer is C
Explanation
Choice A reason: Acidosis does not enhance gastrointestinal potassium absorption. Hyperkalemia in acidosis results from cellular shifts, not increased absorption, as hydrogen ions affect potassium movement, making this choice incorrect.
Choice B reason: Acidosis does not increase renal potassium excretion; it causes hyperkalemia by shifting potassium out of cells. Hypokalemia may occur in alkalosis, not acidosis, making this choice incorrect.
Choice C reason: Acidosis causes hyperkalemia as excess hydrogen ions enter cells to buffer pH, displacing potassium into the bloodstream. This cellular shift elevates serum potassium, making this the correct choice.
Choice D reason: Acidosis promotes potassium release from cells, not uptake, causing hyperkalemia. Hypokalemia occurs in alkalosis, where potassium enters cells, making this choice incorrect for acidosis effects.
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