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NR-507 Mid-Term Study Guide

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Hematology Hematopoiesis (Hemato=blood Poiesis= to form or make) (blood = 7% BW) • Process of creating new blood cells. All blood cells are made in the bone marrow. Stimulated by androgens (testosterone) & erythropoietin made by the kidney & liver in response to tissue hypoxia • Stimulated by infiltration of yellow (fatty) bone marrow with red marrow cells • All blood is created from hematopoietic stem cells (HSC)-( Hemocytoblast ) o Proliferate & differentiate by growth factors & cytokines to form RBC, WBC, & platelets o 4 groups  Lymphoid: T-cell (T-lymphocyte) & B-cell (B-lymphocyte)  Myeloid: Monocyte & Granulocytes (WBC)  Erythrocyte (RBC)  Megakaryocyte (platelets), • Site of formation : o 3rd week gestation, yolk sac, o 8th week gestation, liver & spleen o 5th month gestation, bone marrow o Birth-5yrs, red marrow o 20+ years, larger bones (ilium, vertebrae, cranium, jaw, sternum, ribs, femur, humerus ) • Erythrocyte (RBC) o Normal RBC level = 4.2-6.2 million mm = 45% of our blood volume hemoglobin o Contains molecules : Oxygen carrying molecule, which regulate diffusion through a cell’s plasma membrane, to cells (Hgb can carry up to 4 molecules of oxygen)  Carry oxygen to lungs & exchange it for carbon dioxide in the tissues  Responsible for blood’s ruby-red color  As many as 300 million Hgb molecules/RBC (90% dry weight RBC)  Hbg= polypeptide chains (2alpha & 2 beta), 4 heme molecules, & 4 iron o Oxyhemoglobin : Oxygen binds to iron in heme molecule, RED o Deoxyhemoglobin : CO2 binds Hgb, released in lungs, BLUE o Mature erythrocytes lack a nucleus & organelles, so it cannot synthesize protein or carry out oxidative reactions. Cannot divide = limited life span *Anaerobic metabolism only o Biconcave, spherical disk, reversible o Lifespan : 100-120 days, 1% circulating RBC replenished every 24 hours (2.5 million RBC’s/second ) o Stages : (7-day process )  Hemocytoblast (stem cell) binds with erythropoietin  Proerythroblast- committed to morph into RBC  Erythroblast- ribosome synthesis (2 phases)  Normoblast- Hgb accumulation & nucleus ejection  Reticulocyte – released into circulation, no nucleus, ribosome, or mitochondria  RBC (once in bone marrow 1-2 days) o Size : microcytic, normocytic, macrocytic o Color : hypochromic, normorchromic, hyperchromic (due to Hgb level ) o Variability : Anisocytosis (size), poikilocytosis (shape ) Vitamin B12 (Cyanocobalamin) • Dietary sources: meat, fish, poultry, dairy *NO FRUITS OR VEGGIES • Stomach secretes intrinsic factor protein assists with absorption of ileum • Excess stored in liver (1000X reserve, takes years to deplete stores) Folic acid (Folate) • Dietary sources: liver, grain, green vegies • Required for DNA & RNA synthesis • Prevents neural tube defects in fetus • Excess stored in liver (reserve depleted 2-3 months

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