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36 Cards in this Set
- Front
- Back
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What are the phases of hematopoiesis?
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yolk sac phase
hepatic phase bone marrow phase |
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What is extramedullary hematopoiesis?
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when the liver and spleen reinitiate hematopoiesis
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Postnatally, which organ is responsible for hematopoiesis?
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bone marrow
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What are the characteristics of yellow bone marrow?
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hemapoietically inactive
found in long bones of adults contains numerous adipose cells and undifferentiated mesenchymal cells (reserve of hematopoietic tissue) under stress, can revert to red bone marrow |
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What are the characteristics of red bone marrow?
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active
found primarily in flat bones in adults functions in blood cell production, RBC destruction, and iron storage |
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What are the 3 components of red bone marrow?
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hematopoietic cords
stroma sinusoidal capillaries |
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What are hemaopoietic cords?
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component of red bone marrow
contains clusters of developing blood cells and megakaryocytes |
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What is the stroma?
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component of red bone marrow
network of reticular cells, reticular fibers, and macrophages extracellular matrix molecules (laminin, fibronectin, hemonectin) are important for binding hematopoietic cells to stroma stromal cells produce hematopoietic growth factors (colony-stimulating factors) essential for hematopoiesis |
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What are sinusoidal capillaries?
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component of red bone marrow
large diameter capillaries with a discontinuous layer of endothelial cells thin areas of endothelium may be entrance site for mature cells into bloodstream endothelium supported by underlying reticulum formed by reticular cells and fibers |
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What is the monophyletic theory?
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theory that all blood cells arise from a common stem cell, the pluripotential stem cell
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What are the cells that make up the hematopoeitic lineage? Which one is not self-renewing?
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pluripotential stem cell
multipotential stem cell (lymphoid and myeloid cell) progenitor cell precursor cell *not self-renewing |
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What is erythropoietin?
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hormone essential for RBC development
it is produced by kidneys when they are exposed to low O2 a glycoprotein that stimulates mRNA for globin synthesis |
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What are colony stimulating factors (CSFs)?
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glycoproteins that regulate proliferation and differentiation of stem cells
act at different stages of stem cell differentiation and can act at multiple steps can also stimulate functions of mature cells |
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What is the significance of recombinant CSFs?
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recombinant colony stimulating factors are used clinically to increase blood cell proliferation
e.g. CSFs can enhance success in bone marrow transplants, erythropoietin used to treat anemia due to chronic renal failure, GM-CSF is used to treat neutropenia |
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What is the significance of the Philadelphia chromosome in chronic myeloid leukemia?
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in chronic myeloid leukemia, the Philadelphia chromosome is a marker chromosome (representing a translocation) found in all of the dividing granulocytic, erythrocytic, and megakaryocytic precursors, suggestiong origin from common stem cell
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What are the cellular changes during erythrocyte development and what are they due to?
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decreased cell size
decreased nuclear size increased chromatin condensation change in cytoplasmic color due to accumulation of hemoglobin, a simultaneous decrease in ribosomes, a condensation of nuclear chromatin that results in a pyknotic nucleus and nuclear extrusion |
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What are the morphologically visible stages of erythrocyte development? At which point can the cell no longer divide?
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proerythroblast (pronormoblast)
basophilic erythroblast (basophilic normoblast) polychromatophilic erythroblast (polychromatophilic normoblast) orthochromatic erythroblast (normoblast) - *cell no longer can divide polychromatophilic erythrocyte (reticulocyte) erythrocyte |
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How are senescent erythrocytes removed from circulation?
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macrophage system of spleen, bone marrow, and liver phagocytoses and degrade senescent erythrocytes
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what are the morphologically visible stages of neutrophil development? At which point can the cell no longer divide?
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myeloblast
promyelocyte neutrophilic myelocyte neutrophilic metamyelocyte - *cell no longer can divide band/stab cell mature/segmented neutrophil |
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What is neutropenia and its possible causes?
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decrease in number of neutrophils
could be due to decreased production b/c of irradiation, pharmaceuticals, viral infections, or alcohol use could be due to ineffective production as in megaloblastic anemia could be due to increased destruction as occurs in overwhelming infections |
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What is neutrophilia and its causes?
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increase in number of circulating neutrophils
causes: bacterial infections (shift to left), tissue injury such as burns, emotional stress, physical stress as seen during exercise (temporary) |
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What happens in platelet formation?
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CFU-GEMM --> CFU-Meg --> megakaryoblast (large, polyploidal cells) --> megakaryocyte
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What happens in agranulocyte maturation?
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pleuripotential stem cell --> CFU-L --> CFU-LyB or CFU-LyT
lymphocytes likely to all arise from bone marrow T lymphocytes migrate to thymus to mature B lymphocytes mature in bone marrow |
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What cells are involved in monocyte maturation?
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CFU-GEMM --> monoblast --> promonocyte --> monocyte
only in circulation for 8 hours then enter connective tissue by diapedesis mature into macrophages in connective tissue; long-lived |
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What cellular changes are taking place during granulocytopoiesis?
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initial accumulation of azurophilic granules followed b a dilution of these granules by cell division and an accumulation of specific granules
nucleus flattens indents, and ultimately lobulates |
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What are the characteristics of a proerythroblast?
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relatively large cell (12-15 um)
basophilic cytoplasm large nucleus with one or two prominent nucleoli not easily identified in blood smears cell can divide |
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What are the characteristics of a basophilic erythroblast?
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very basophilic cytoplasm
round nucleus with distinct, open spaces in chromatin (checkerboard pattern) cell can divide |
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What are the characteristics of polychromatophilic erythroblasts?
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cytoplasm takes on grayish appearance due to simultaneous accumulation of hemoglobin and reduction of rRNA
nucleus smaller with fewer spaces in chromatin cell can divide |
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What are the characteristics of a orthochromatophilic erythroblast?
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cytoplasm nearly the color of RBC's
nucleus very small, eccentric, and dark (pyknotic) with no spaces in chromatin |
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What are the characteristics of a reticulocyte?
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retention of some rRNA that can only be detected with cresyl blue stain
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What are the characteristics of a promyelocyte?
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basophilic cytoplasm
numerous prominent azurophilic granules oval nucleus cell can divide |
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What are the characteristics of a neutrophilic myelocyte?
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first appearance of specific granules
nucleus flattened on one side, eccentrically poisitioned cell can divide |
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What are the characteristics of a neutrophilic metamyelocyte?
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more specific granules
indented nucleus cell cannot divide |
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What are the characteristics of a band/stab cell?
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U-shaped or horseshoe-shaped nucleus
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What are the kinetics of erythropoiesis?
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mitoses occur in proerythroblasts, basophilic erythroblasts, and polychromatophilic erythroblasts
bone marrow is not a storage site for RBCs, nearly all RBCs are released into circulation kidney synthesizes erythropoietin which acts on receptors on CFU-E receptors lifespan about 120 days RBCs broken down by macrophage system of spleen, bone marrow, and liver --> bilirubin forms |
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Describe generally the kinetics of neutrophil production.
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in bone marrow there are 2 compartments:
1. medullary formation compartment, which has a mitotic and maturation compartment 2. medullary storage compartment: acts as reserve; can release large numbers of neutrophils to circulation in the vascular compartment there are 2 pools that are in dynamic equilibrium: 1. circulation pool 2. marginating pool - serves as reservoir, cells adhere to endothelium neutrophils enter CT via diapedesis lifespan of 1-4 days regardless of phagocytic activity |
