Hematology
Hematopoiesis
(Hemato=blood Poiesis= to form or make) (blood = 7% BW)
• Process of creating new blood cells. All blood cells are made in
... [Show More] 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 [Show Less]