Laboratory Studies: Red Cell Indices: Evaluation of RBC saturation with Hb, 32-36%

Correct Answer: C

Rationale: The correct answer is C: MCHC. MCHC stands for Mean Corpuscular Hemoglobin Concentration, which is a measure of the average concentration of hemoglobin in a given volume of packed red blood cells. In this case, a saturation of 32-36% indicates the concentration of hemoglobin in the red blood cells. MCV (Mean Corpuscular Volume) measures the average volume of a red blood cell, MCH (Mean Corpuscular Hemoglobin) measures the average amount of hemoglobin in a red blood cell, and RDW (Red Cell Distribution Width) measures the variation in red blood cell size. These parameters do not directly indicate the saturation of hemoglobin in red blood cells, making them incorrect choices for this scenario.

Correct Answer: B

Rationale: The correct answer is B: Dipyridamole. Dipyridamole works by inhibiting the enzyme phosphodiesterase, leading to an increase in cyclic adenosine monophosphate (cAMP) levels. This increase in cAMP levels potentiates the effect of prostacyclins, which inhibit platelet stickiness and decrease platelet adhesion to thrombogenic surfaces. Rationale: A: Sulfinpyrazone is a uricosuric agent, not a platelet anti-aggregant. C: Ticlopidine and D: Clopidogrel are both antiplatelet agents but work by different mechanisms (ADP receptor antagonists). They do not potentiate prostacyclins and do not directly affect cAMP levels.

Correct Answer: B

Rationale: The correct answer is B because Chronic Lymphocytic Leukemia (CLL) is characterized by the gradual accumulation of small mature B cells in the blood and bone marrow. B cells are lymphocytes that play a key role in the immune system. Choice A (T cells) is incorrect because CLL primarily involves B cells, not T cells. Choice C (NK cells) is incorrect because CLL does not involve natural killer (NK) cells. Choice D (Mixed) is incorrect because CLL is characterized by the accumulation of a single type of cell, specifically mature B cells.

Correct Answer: D

Rationale: Correct Answer: D Rationale: 1. During the mesoblastic phase of erythropoiesis in the yolk sac, only erythroblasts develop. 2. Erythroblasts are precursors of red blood cells and are responsible for producing hemoglobin. 3. Other choices (A, B, C) mention specific types of hemoglobins or cells that are not directly related to the mesoblastic phase. 4. Hb F, Hg A2, Hg A are adult hemoglobin types, Gower 1 and Gower 2 are embryonic hemoglobins, and Portland Hgb is an abnormal hemoglobin. 5. Therefore, the correct answer is D because only erythroblasts develop from yolk sacs during the mesoblastic phase.

Correct Answer: D

Rationale: The correct answer is D because the transferrin receptor is responsible for transporting transferrin-bound iron into cells, particularly erythrocytes. This process allows for the delivery of iron to cells for various biological functions, such as hemoglobin synthesis. Choice A is incorrect as iron is typically absorbed into duodenal cells, not transported out. Choice B is incorrect as it does not align with the role of the transferrin receptor in importing iron. Choice C is incorrect as the transferrin-bound iron in the plasma is not directly handled by the transferrin receptor but rather serves as a carrier for iron transport.