Blood Composition Formed Elements

Erythrocytes Transports oxygen to cells and tissues Transports oxygen to cells and tissues Anucleate Anucleate ~7 µm ~7 µm Few organelles Few organelles Hemoglobin Hemoglobin – Iron rich protein – Binds with oxygen

Erythrocyte Characteristics Small, flexible, bi-concave discs Small, flexible, bi-concave discs – Center is depressed to increase surface area – Cell must be flexible to fold to cross capillaries Amount of oxygen carried directly related to hemoglobin concentrations Amount of oxygen carried directly related to hemoglobin concentrations – ~250 million hgb molecules per cell!

Hemoglobin Made up of 4 connected protein chains Made up of 4 connected protein chains Responsible for the red color of blood Responsible for the red color of blood Forms the heme molecule Forms the heme molecule – Important Carries oxygen, returns carbon dioxide Carries oxygen, returns carbon dioxide Helps maintain structure of cell Helps maintain structure of cell

Leukocytes Contain nuclei & organelles Contain nuclei & organelles Body’s “Army” Body’s “Army” – Defends/protects body – WBC’s move to fight infection Can leave blood stream-diapedesis Can leave blood stream-diapedesis Positive chemotaxis Positive chemotaxis – Damaged cells give off chemicals to alert body – Activates WBC’s – Body will produce more of that type WBC

Leukocytes Two major groups Two major groups – Granulocytes Cytoplasm contains visible granular inclusions Cytoplasm contains visible granular inclusions Lobed nuclei Lobed nuclei – Agranulocytes Cytoplasm does not have visible granules Cytoplasm does not have visible granules Spherical nuclei Spherical nuclei – Oval – Kidney shaped

Granulocytes Neutrophils Neutrophils – Most numerous WBC – Multi-lobed nucleus – Fine granules – Phagocytic cell FUNGI FUNGI BACTERIA BACTERIA

Granulocytes Eosinophils Eosinophils – Bluish red nuclei – Nucleus is usually bi-lobed – Coarse, red granules – Increase due to Allergies Allergies Parasites Parasites

Granulocytes Basophils Basophils – Rare WBC – Nucleus “u” or “s” shaped – Granules stain dark blue/purple – Helps mediate inflammatory response Contains histamine Contains histamine – Makes blood vessels leaky to allow WBC to get to inflammation site Contains heparin Contains heparin – Anti-coagulant

Agranulocytes Lymphocytes Lymphocytes – Small (slightly bigger than a RBC) – Dark staining nucleus – Second most numerous WBC – Tend to reside in lymph tissues – Important in antibody production – Increase in response to VIRUSES

Agranulocytes Monocytes Monocytes – Largest WBC – “U” or kidney shaped nucleus – Convert into macrophages in tissues – Seen in chronic infections

Platelets Not a true cell Not a true cell – Fragments of megakaryocytes – Dark staining pieces – Critical to clotting process Bind together to stop bleeding Bind together to stop bleeding

Complete Blood Counts Measures Measures – The number of RBC’s – The number of WBC’s – The number of platelets – Hgb – Hematocrit Can include Can include – Morphology of RBC’s – Size of RBC’s

Typical CBC results RBC count (varies): – Male: 4.7 to 6.1 million cells/µL – Female: 4.2 to 5.4 million cells/µL WBC count: 4,500 to 10,000 cells/µL Hematocrit (varies): – Male: 40.7 to 50.3 % – Female: 36.1 to 44.3 % Hemoglobin (varies): – Male: 13.8 to 17.2 gm/dL – Female: 12.1 to 15.1 gm/dL

Typical CBC results Segmented neutrophils: (50–70%) Lymphocytes: (15–45%) Monocytes: ( 0–10%) Eosinophils: (0–6%) Basophils: (0–2%)