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CH 17 – RBC Morphology. Erythrocytes. >99% of the formed elements function to carry O 2 , CO 2 & H + anatomy biconcave disks, 8 µm in diameter no nucleus limited metabolic activity ~280 million hemoglobin (Hgb) molecules/cell O 2 carrying protein
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Erythrocytes • >99% of the formed elements • function to carry O2, CO2 & H+ • anatomy • biconcave disks, 8 µm in diameter • no nucleus • limited metabolic activity • ~280 million hemoglobin (Hgb) molecules/cell • O2 carrying protein • synthesized in cytosol before the nucleus is lost • 33% of cell weight
Erythrocytes • Bi-Concave disc shape • creates a higher surface area/volume ratio increases gas diffusion • very flexible structure allows passage through capillaries • the smallest capillaries are no wider than an RBC
Erythrocytes • Normal Hgb in blood • Infants: 14-20g Hgb/100ml • Adults: • Males: 14-15g Hgb /100ml • Females: 12-15g Hgb /100 ml
RBC’s (Electron Microscopy) electron microscopy
HemoglobinStructure • O2 combines with Hgb in lungs • O2 not very soluble in H2O • O2 needs a molecular transporter to carry it • Hemoglobin • 4 globin (protein) chains - 2 α chains & 2 β chains • 4 non-protein heme pigments (lipid) • each heme pigment has iron ion (Fe²+) that carries 1 O2 • each RBC can carry about 1 billion O2 molecules • RBC's carry ~25% of the CO2 bound to Hgb - forms carbaminohemoglobin
Erythrocyte (RBC) Life Span • Life span • only 100-120 days • cannot repair damage due to loss of nucleus, ribosomes • Old RBC’s destroyed in the spleen, liver and the bone marrow • Macrophages phagocytize old worn RBC's • Breakdown products are recycled • Different pathways exist for each part of the Hgb molecule • globin chains - AA's used for other protein synthesis • heme • iron portion - Fe2+ recycled • non-iron lipid portion – converted to bilirubin - waste • released into blood, secreted by the liver into bile • bile enters intestine, is converted to urobilinogen by bacteria • contributes to urine & feces color
End RBC Morphology CH 17