Hematopoiesis Practice Questions Flashcards
Which of the following hematopoietic cells would you predict is the most numerous in bone marrow?
A) Orthochromatophilic erythroblast
B) CFU-Eo
C) Neutrophilic band cell
D) CFU-Ba
E) Neutrophilic myelocyte
The correct answer is A. I didn’t discuss the relative abundance of different hematopoietic types in the Hematopoeisis lecture. It should be obvious however upon reflection that the member of the erythrocyte development pathway listed (orthochromatophilic erythroblast) would be more abundant than the other choices (which are all stages in development of different granulocytes) because erythrocytes are so much more numerous than granulocytes in the body. Orthochromatophilic erythroblasts also do not divide again so they have reached the maximum number for the lineage of daughter cells derived from a single stem cell. The more immature stem cells (CFU-Eo and CFU-Ba) would be relatively quite rare as they will divide several more times and they are in the lineages of the less abundant granulocytes as well.
Which of the following are the most abundant in red bone marrow stroma?
A) Skeletal muscle cells
B) T lymphocytes
C) Macrophages
D) Smooth muscle cells
E) Platelets
The correct answer is C. There is at least one macrophage nurse cell associated with each colony of developing erythrocytes in the bone marrow stroma. These phagocytic cells are needed to phagocytose the nuclei and other organelles that are extruded as the erythrocytes develop. T lymphocytes develop in the thymus not bone marrow stroma , so B is incorrect. No platelets at all are in bone marrow stroma. The megakaryocyte extends its cytoplasmic processes into the sinusoids, where bits break off and become platelets only in the sinusoids, so E is incorrect. You haven’t studied bone yet, but there really isn’t any skeletal or smooth muscle in red bone marrow and that is why they weren’t mentioned in the lecture, so A and D are incorrect.
Which of the following is NOT a characteristic of erythropoietin (EPO)?
A) EPO is secreted by cells of the kidney in response to low oxygen levels in the blood
B) EPO is a protein
C) The survival of the CFU-GEMM hematopoietic stem cells is dependent on the presence of EPO
D) EPO is a cytokine for erythrocyte precursors in the bone marrow
E) Having a higher than normal amount of EPO is associated with an increased risk of adverse cardiovascular complications
The correct answer is C. Note that we are looking for what is NOT a characteristic of EPO. Too much EPO can lead to too high a hematocrit. The heart has to work much harder to push the thicker blood, which can lead to heart problems. Too high of a hematocrit can also lead to clot formation, which also can cause cardiovascular problems. Thus, E is a characteristic of EPO. EPO is a secreted protein (actually a glycoprotein) as are all cytokines, so B is a characteristic of EPO. EPO is secreted by cells of the kidney, so A is a characteristic of EPO. CFU-E is an erythrocyte precursor, so D is a characteristic of EPO. However, CFU-GEMM is not the main target of EPO, CFU-E is, so C is not a characteristic of EPO and is therefore the correct answer.
Which of the following is a cell type that is descended from the CFU-GM hematopoetic stem cell?
A) Osteoclast
B) Lymphocyte
C) Chondroblast
D) Erythrocyte
E) Fibroblast
The correct answer is A. Many macrophages fuse together to form an osteoclast. Monocytes/macrophages come from CFU-GM (as do neutrophils). Lymphocytes come from CFU-L. Chondroblasts (that form cartilage) and fibroblasts do not come from hematopoetic stem cells.
Which of the following occurs during erythropoeisis?
A) The cells become larger
B) The cells become attached to a substratum instead of being free-floating
C) The development of cellular granules containing clotting factors
D) The development of cellular granules containing the major basic protein
E) The loss of cellular organelles
The correct answer is E. Reticulocytes and erythrocytes are free-floating, they do not attach to a substratum, so B is incorrect. C is true of platelets, but not erythrocytes. D is true of eosinophils, but not erythrocytes. The cells become smaller not larger, so A is incorrect.
ANSWERS!
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