The underlying pathophysiology of sickle-cell anemia is:
A loss of red blood cells, white blood cells, and platelets.
Abnormally-shaped red blood cells that cause obstruction of small blood vessels.
Increased numbers of circulating red blood cells and hemoglobin.
Decreased red blood cells due to a lack of intrinsic factor.
The Correct Answer is B
A. A loss of red blood cells, white blood cells, and platelets is incorrect because sickle-cell anemia primarily affects red blood cells. White blood cells and platelets are usually unaffected in terms of production; the condition does not cause a pancytopenia like aplastic anemia.
B. Abnormally-shaped red blood cells that cause obstruction of small blood vessels is correct because sickle-cell anemia is caused by a mutation in the beta-globin gene, resulting in hemoglobin S. Under low oxygen conditions, hemoglobin S polymerizes, causing red blood cells to become rigid, crescent-shaped (sickle-shaped), and less flexible. These sickled cells block small blood vessels, leading to vaso-occlusion, ischemia, pain crises, and organ damage. Additionally, sickled cells are prone to hemolysis, resulting in chronic anemia.
C. Increased numbers of circulating red blood cells and hemoglobin is incorrect because sickle-cell anemia results in hemolytic anemia, meaning red blood cell counts and hemoglobin levels are reduced, not increased.
D. Decreased red blood cells due to a lack of intrinsic factor is incorrect because this describes pernicious anemia, not sickle-cell anemia. Sickle-cell anemia is a genetic hemoglobinopathy, not a vitamin B12 absorption issue.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Barrel chest is correct because advanced emphysema causes hyperinflation of the lungs due to air trapping. Over time, the anteroposterior diameter of the chest increases, giving the characteristic “barrel-shaped” appearance. This occurs because the alveoli are damaged, air is retained, and the lungs remain chronically overinflated, which also flattens the diaphragm and contributes to difficulty with effective respiration.
B. Constant productive cough is incorrect because a productive cough is more characteristic of chronic bronchitis, another form of COPD. Emphysema primarily involves alveolar destruction and airflow obstruction, so cough is usually minimal or dry in contrast to chronic bronchitis.
C. Underinflation of the lungs is incorrect because emphysematous lungs are overinflated, not underinflated. Hyperinflation leads to increased residual lung volume and the “barrel chest” deformity.
D. Arched diaphragm is incorrect because in emphysema, the diaphragm becomes flattened, not arched, due to lung hyperinflation and air trapping. A flattened diaphragm reduces the efficiency of inspiration, contributing to shortness of breath and use of accessory muscles.
Correct Answer is B
Explanation
A. Increased venous pressure causing edema in the legs is incorrect because edema and venous congestion are associated with venous insufficiency, not intermittent claudication. Intermittent claudication is an arterial problem, not a venous one.
B. Decreased blood flow in leg muscles due to atherosclerosis is correct because atherosclerotic plaques narrow the arteries, reducing oxygen-rich blood flow to the muscles during activity. When the leg muscles require more oxygen during exercise or walking, the insufficient blood supply leads to ischemia, causing pain, cramping, or fatigue. This pain typically resolves with rest, which is why it is called intermittent claudication.
C. Increased cardiac output leading to muscle fatigue is incorrect because the pain is not due to cardiac output. While heart function affects overall perfusion, intermittent claudication is localized ischemic pain in the leg muscles caused by arterial obstruction, not by the heart pumping more blood.
D. Decreased stimulation of nerves in the leg muscles is incorrect because the pain results from ischemia, not nerve inactivity. In fact, nerve endings in the muscles may contribute to the sensation of pain due to oxygen deprivation, but the primary cause is reduced arterial blood flow.
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