Blood Composition
Formed Elements
Erythrocytes
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Transports oxygen to cells and tissues
Anucleate
~7 µm
Few organelles
Hemoglobin
– Iron rich protein
– Binds with oxygen
Erythrocyte Characteristics
• 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
– ~250 million hgb molecules per cell!
Hemoglobin
• Made up of 4 connected protein chains
• Responsible for the red color of blood
• Forms the heme molecule
– Important
• Carries oxygen, returns carbon dioxide
• Helps maintain structure of cell
Leukocytes
• Contain nuclei & organelles
• Body’s “Army”
– Defends/protects body
– WBC’s move to fight infection
• Can leave blood stream-diapedesis
• 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
– Granulocytes
• Cytoplasm contains visible granular inclusions
• Lobed nuclei
– Agranulocytes
• Cytoplasm does not have visible granules
• Spherical nuclei
– Oval
– Kidney shaped
Granulocytes
• Neutrophils
–Most numerous WBC
–Multi-lobed nucleus
–Fine granules
–Phagocytic cell
• FUNGI
• BACTERIA
Granulocytes
• Eosinophils
– Bluish red nuclei
– Nucleus is usually bi-lobed
– Coarse, red granules
– Increase due to
• Allergies
• Parasites
Granulocytes
• Basophils
– Rare WBC
– Nucleus “u” or “s” shaped
– Granules stain dark blue/purple
– Helps mediate inflammatory response
• Contains histamine
– Makes blood vessels leaky to allow WBC to get to
inflammation site
• Contains heparin
– Anti-coagulant
Agranulocytes
• 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
– Largest WBC
– “U” or kidney shaped nucleus
– Convert into macrophages in tissues
– Seen in chronic infections
Platelets
• Not a true cell
– Fragments of megakaryocytes
– Dark staining pieces
– Critical to clotting process
• Bind together to stop bleeding
Complete Blood Counts
• Measures
– The number of RBC’s
– The number of WBC’s
– The number of platelets
– Hgb
– Hematocrit
• 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
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Segmented neutrophils: (50–70%)
Lymphocytes: (15–45%)
Monocytes: (0–10%)
Eosinophils: (0–6%)
Basophils: (0–2%)