The blood transports more CO2 in the form of _______than in any other form.
carbaminohemoglobin
bicarbonate ions
bisphosphocarbonate
carboxyhemoglobin
dissolved CO2 gas
The Correct Answer is B
A. Carbaminohemoglobin: About 20–30% of CO₂ binds to hemoglobin forming carbaminohemoglobin. While this contributes to CO₂ transport, it is significantly less than the amount carried as bicarbonate ions.
B. Bicarbonate ions: Most CO₂ (around 70%) in the blood is converted to bicarbonate ions (HCO₃⁻) via carbonic anhydrase in red blood cells. This allows efficient transport from tissues to lungs and facilitates rapid CO₂ release during exhalation.
C. bisphosphocarbonate: This is not a recognized form of CO₂ transport in blood. It does not play a role in carrying CO₂ from tissues to the lungs and is not physiologically relevant.
D. Carboxyhemoglobin: Carboxyhemoglobin forms when carbon monoxide binds to hemoglobin, not CO₂. It does not participate in normal CO₂ transport and is mainly a concern in CO poisoning.
E. Dissolved CO₂ gas: Only a small fraction (about 7–10%) of CO₂ is dissolved directly in plasma. This amount is minimal compared to the majority transported as bicarbonate ions.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Mucous membranes line the respiratory, gastrointestinal, and genitourinary tracts, serving as a primary barrier against pathogens. The mucus traps microbes and particulate matter, while enzymes like lysozyme break down bacterial cell walls. Together, these defenses reduce the likelihood of infection by preventing many pathogens from entering the body.
Correct Answer is D
Explanation
A. Aorta and pulmonary veins:The aorta carries oxygen-rich blood from the left ventricle to the systemic circulation, and pulmonary veins carry oxygenated blood from the lungs to the left atrium. Neither carries oxygen-poor blood.
B. Pulmonary veins and pulmonary arteries:Pulmonary veins transport oxygen-rich blood from the lungs to the heart, whereas pulmonary arteries carry oxygen-poor blood from the right ventricle to the lungs. Only the pulmonary arteries carry oxygen-poor blood.
C. Pulmonary veins and vena cava:Pulmonary veins carry oxygen-rich blood, and the vena cavae carry oxygen-poor blood. This combination is only partially correct regarding oxygen-poor blood.
D. Vena cavae and pulmonary arteries:The superior and inferior vena cavae return oxygen-poor blood from the body to the right atrium, and the pulmonary arteries carry oxygen-poor blood from the right ventricle to the lungs for oxygenation. Both vessels carry deoxygenated blood, making this the correct answer.
E. Aorta and vena cavae:The aorta carries oxygen-rich blood, so this pair is incorrect. Only the vena cavae carry oxygen-poor blood.
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