AAB MT Hematology |232 questions with 100% correct answers.

What is hemoglobin composed of? 4 heme, 4 iron, 4 globins What disorder does a defect in heme synthesis lead to? Porphyria Porphyria Deficiency in the enzymes of the porphyrin pathway leads to insufficient production of heme. The principal problem in these deficiencies is the accumulation of porphyrins, the heme precursors, which are toxic to tissue in high concentrations. What is methemoglobin? Methemoglobin is a form of hemoglobin that contains ferric [Fe3+] iron and has a decreased ability to bind oxygen. However, the ferric iron has an increased affinity for bound oxygen. When methemoglobin concentration is elevated in red blood cells, tissue hypoxia can occur. What is the function of the enzyme methemoglobin-cytochrome C reductase in a red blood cell? To keep iron in the ferrous state What product is formed when ferrous iron of hemoglobin is oxidized to the ferric state? Methemoglobin What is carboxyhemoglobin? A stable complex of carbon monoxide and hemoglobin that forms in RBCs when carbon monoxide is inhaled or produced in normal metabolism. Large quantities of it hinder delivery of O2 to the body. Tobacco smoking (through carbon monoxide inhalation) raises the blood levels of COHb by a factor of several times from its normal concentrations. Which hemoglobin has a 200 times greater binding capacity for the hemoglobin molecule than oxygen? Carboxyhemoglobin Which hemoglobin derivative causes irreversible changes in RBCs? Sulfhemoglobin -- makes blood incapable of carrying oxygen. Which of the following hemoglobins is NOT normally present in a normal adult? Hb-S Which embryonic hemoglobin is normally found in newborns? Hb-F What is the most abundant hemoglobin in a newborn? Hb-F What is the molecular structure of Hemoglobin S? Valine replaces glutamic acid in the 6th position of the beta chain Which of the following hemoglobins is insoluble under lowered oxygen tension? Hb-S What laboratory test is used to confirm the specific diagnosis of sickle cell anemia? Hemoglobin electrophoresis In the solubility test for hemoglobin S, what is the reagent responsible for the reduction of the hemoglobin molecule? Sodium dithionite In hemoglobin C, what replaces glutamic acid? Lysine Which red blood cell inclusion is characteristic of hemoglobin C disease? Rod-shaped crystals What is hemoglobin F composed of? 2 alpha and 2 gamma chains Which hemoglobin is resistant to alkali denaturation? Hb-F Which hemoglobins are differentiated by the Kleihauer-Betke technique? Hb-A1 from Hb-F What is the order of migration of hemoglobins, from fastest to slowest, on cellulose acetate at pH 8.4? A1, F, S, C Why is citrate agar used when abnormal hemoglobins are identified on cellulose acetate at pH 8.6? It separates hemoglobin S from hemoglobin D The cyanmethemoglobin method measures all hemoglobin pigments EXCEPT which one? Sulfhemoglobin What is the diluent used in the cyanmethemoglobin method for the determination of hemoglobin? Drabkin's solution What is the normal plasma hemoglobin concentration? 2-3 mg/dL Which plasma protein binds free hemoglobin? Haptoglobin Which one of the following statements concerning hemolytic anemia is false? The serum haptoglobin is increased In this type of anemia RBCs are normocytic and normochromic. RBCs, hemoglobin, and hematocrit are decreased and the indirect bilirubin is increased. Hemolytic anemia Myoglobin can be separated from hemoglobin by saturating the specimen with which one of the following reagents? Ammonium sulfite The hematocrit is also known as which one of the following terms? Packed red blood cell volume The degree of packing of cells during centrifugation depends on all of the following EXCEPT which one? Bore size of the microhematocrit tube The degree of packing of cells during centrifugation depends on all of the following: Speed of the centrifugation, radius of centrifugation, and time of centrifugation. During examination of a spun hematocrit, in which layer are the white blood cells found? Buffy coat