., which is essential for allowing CO2and H20 to react.(buffer system more later)Hemoglobin- consists of four protein chains attached to a heme (iron containing) group. One oxygen atom can bind to each heme group therefore making the hemoglobin completely saturated.Carbon monoxide binds irreversibly to hemoglobin, thus rendering it ineffective to carry oxygen.Fetal hemoglobin is much more effective at binding oxygen than is adult hemoglobin.Iron is necessary for hemoglobin to function, properly and without it anemia can ensue.Main component of RBCB.Formation of RBC’s1.General InformationHematopoiesis takes place in the red bone marrow.Marrow makes about an ounce of blood each day.Hemocytoblast – stem cells for blood cell production.2.Erythropoiesis – formation of RBC’sHemocytoblastmyeloid stem cellproerythroblastearly erythroblastlate erythroblast normoblastreticulocyteerythrocyte.oHemocytoblast: bone marrow stem cell, can become any blood celloProerythroblast: RBC stem cell, has receptors for EPOoErythroblast: begins making hemoglobinoReticulocyte: often found in hypoxic situationsHemoglobin begins accumulating in the second phaseNucleus is ejected form the normoblast.RBC’s are produced at a rate of about 2 million/sec!3.Hormonal Controls3
Nur 0013Spring 2014Erythropoietin (EPO) – hormone released by kidney cellsin response to:Decreased RBC in circulationDecreased O2availabilityIncreased tissue demands for O2EPO stimulates red bone marrow to produce more RBC’sWithin 1-2 days reticulocyte count increases.Hypoxia is a major factor in stimulating this systemC.Death of RBC - HemolysisAfter 90-120 days membrane becomes fragile and rigidMembrane degraded in either spleen or liverHemoglobin disposed by liver.Broken into heme and globin componentsHeme broken down into bilirubin in SI, and iron is recycled.Globins – are recycled D.RBC disorders.Are often related to not enough or too many cellsAnemias – Lack of RBC’s- blood loss, malformationHemorrhagicHemolytic (Ecoli)4
Nur 0013Spring 2014Aplastic(bone marrow destroyed)Low Hemoglobin countsIron DeficientPernicious(lack of intrinsic factor and hence vit B12)Defective Hemoglobin – Often geneticThalassemias – faulty globin chainsSickle cell, single amino acid change during transcriptionCauses the cell to become stiff and elongated due to malformed hemoglobinOne of the more common genetic diseases that affects RBCPolycythemias Polycythemia vera – often caused by marrow cancer.Blood doping – secondary causeIV.Formed Elements - WBCA.Leukocytes (WBC) ~5000-10,000/µLAre truly cells, they are only about 1% of blood by volume.Hormones and other stressors can stimulate their production in red bone marrow (known as leukopoeisis).Stimulants for formation can be hormonal or other stressorsOnce produced they move out of the blood vessels in a process known as diapedesisand eventually to the site of an immune response.