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Unformatted text preview: Erythrocyte Structure and Hemoglobin Function Composition of Blood-formed elements (cells) are suspended and carried in plasma ( cell-free fluid)-centrifuged blood separates into heavier elements on bottom and plasma on top-total blood volume: 5 L (7% body weight)-plasma : straw-colored liquid containing water and dissolved solutes (ions, metabolites, hormones)-erythrocytes = RBC= most common formed blood elements-hematocrit (Hct)= % RBC in centrifuged blood-women= 36-46%-men=41-53% Hb= 12-16g/ 100mL of blood Formed elements of blood= RBC-flattened biconcave discs-shape provides large surface area for diffusion and deformability-no nuclei or mitochondria-about 300 billion produced/ day Hematopoiesis= formation of blood cells from stem cells in the myeloid tissue (bone marrow) Erythropoiesis (formation of RBC)- stimulated by erythropoietin (EPO) *a protein hormone secreted by kidneys when O2 delivery is reduced to the organ-2.5 million new RBC-mean lifespan= 120 days-old RBC removed by phagocytes in the liver, sleep, and bone marrow-iron from old RBC is recycled into hemoglobin production Role of hemoglobin (Hb) in O2 transport-each adult Hb molecule contains 4 goblin protein chains-2 alpha-2 beta = four heme groups-each heme binds one O2 molecule...
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- Fall '10
- Hemoglobin, O2 transport, adult Hb molecule