HOW BLOOD IS PRODUCED Red bone marrow produces all seven formed elements

How blood is produced red bone marrow produces all

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HOW BLOOD IS PRODUCED Red bone marrow produces all seven formed elements Pluripotent stem cells (PPSC) Formerly called hemocytoblasts or hemopoietic stem cells Colony-forming unit—specialized stem cells only producing one class of formed element of blood Myeloid hemopoiesis—blood formation in the bone marrow Lymphoid hemopoiesis—blood formation in the lymphatic organs (beyond infancy this only involves lymphocytes)
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ERYTHROCYTES Two principal functions Carry oxygen from lungs to cell tissues Pick up CO 2 from tissues and bring to lungs Insufficient RBCs can cause death in minutes due to lack of oxygen to tissues Disc-shaped cell with thick rim Lack mitochondria Anaerobic fermentation to produce ATP Lack of nucleus and DNA No protein synthesis or mitosis
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HEMOGLOBIN
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SICKLE CELLSHereditary defects that occur mostly among people of African descent
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QUANTITIES OF ERYTHROCYTES AND HEMOGLOBIN RBC count and hemoglobin concentration indicate amount of O 2 blood can carry Hematocrit (packed cell volume): percentage of whole blood volume composed of RBCs Men 42% to 52% cells; women 37% to 48% cells Hemoglobin concentration of whole blood Men 13 to 18 g/dL; women 12 to 16 g/dL RBC count Men 4.6 to 6.2 million/ L; women 4.2 to 5.4 million/ L
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IRON METABOLISM Iron—key nutritional requirement Lost daily through urine, feces, and bleeding Men 0.9 mg/day and women 1.7 mg/day Low absorption rate of iron requires consumption of 5 to 20 mg/day
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IRON METABOLISM Dietary iron: ferric (Fe 3+ ) and ferrous (Fe 2+ ) Stomach acid converts Fe 3+ to absorbable Fe 2+ Gastroferritin binds Fe 2+ and transports it to small intestine Absorbed into blood and binds to transferrin for transport to bone marrow, liver, and other tissues - Bone marrow for hemoglobin, muscle for myoglobin, and all cells use for cytochromes in mitochondria Liver apoferritin binds to create ferritin for storage
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IRON METABOLISM Vitamin B 12 and folic acid Rapid cell division and DNA synthesis that occurs in erythropoiesis Vitamin C and copper Cofactors for enzymes synthesizing hemoglobin Copper is transported in the blood by an alpha globulin called ceruloplasmin
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ERYTHROCYTE HOMEOSTASIS Negative feedback control Drop in RBC count causes hypoxemia detected by kidney
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