1. CH 17 – RBC Morphology

2. 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  synthesized in cytosol before the nucleus is lost  33% of cell weight

3. 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

4. Erythrocytes Normal Hgb in blood  Infants: 14-20g Hgb/100ml  Adults:  Males: 14-15g Hgb /100ml  Females: 12-15g Hgb /100 ml

5. RBC’s (Electron Microscopy) electron microscopy

6. Hemoglobin Structure  O 2 combines with Hgb in lungs  O 2 not very soluble in H 2 O  O 2 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 O 2  each RBC can carry about 1 billion O 2 molecules  RBC's carry ~25% of the CO 2 bound to Hgb - forms carbaminohemoglobin

7. 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 - Fe 2+ 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

8. RBC Life Span

9. End RBC Morphology CH 17