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 D
Explanation
Choice A reason: The glycosylated hemoglobin (HbA1c) test does not measure erythrocyte count. It reflects glucose binding to hemoglobin, indicating average blood glucose over months, not red cell quantity, making this choice incorrect.
Choice B reason: HbA1c does not measure insulin production but reflects glucose levels bound to hemoglobin over 2-3 months. Insulin production is assessed by other tests, like C-peptide, making this choice incorrect.
Choice C reason: HbA1c does not directly measure diabetes medication effectiveness but provides a long-term glucose control average. Medication efficacy is inferred indirectly, making this choice incorrect for the test’s primary purpose.
Choice D reason: The HbA1c test measures average blood glucose over 2-3 months by assessing glucose bound to hemoglobin in red cells, reflecting long-term glycemic control, making this the correct choice.
Correct Answer is C
Explanation
Choice A reason: Melena is dark, tarry stool due to upper gastrointestinal bleeding, not greasy or foul-smelling from malabsorption. It results from digested blood, not fat malabsorption, making this choice incorrect for the described diarrhea.
Choice B reason: Small-volume diarrhea is typically due to inflammation, like in inflammatory bowel disease, not malabsorption. It lacks the greasy, foul-smelling quality of fat malabsorption, making this choice incorrect for malabsorption-related diarrhea.
Choice C reason: Steatorrhea is greasy, foul-smelling diarrhea caused by fat malabsorption, common in disorders like celiac disease or pancreatic insufficiency. Undigested fats in stool cause its characteristic appearance and odor, making this the correct choice.
Choice D reason: Osmotic diarrhea results from unabsorbed solutes, like lactose intolerance, causing watery stools, not specifically greasy or foul-smelling. It lacks the fat content of steatorrhea, making this choice incorrect for malabsorption diarrhea.
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