II. Physiology: White Blood Cells (Leukocytes, WBC)
- Images
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Bone Marrow: Stem cells differentiation and storage
- Megakaryoblasts
- Erythroblasts
- Erythrocytes
- Lymphoblasts
- Lymphocytes (20-40% of peripheral WBCs)
- Myeloblasts develop into Granulocytes
- Neutrophil (40-60 of peripheral WBCs)
- Eosinophil (1-4% of peripheral WBCs)
- Basophil (0.5-1% of peripheral WBCs)
- Monocyte (2-8% of peripheral WBCs)
- Peripheral Blood
- Leukocytes remain in storage in Bone Marrow: 80-90%
- Proliferate and mature over 7 days
- Stored in the marrow up to 7 days
- Only 2-3% of Leukocytes enter circulation (unless mobilized)
- Life span of White Blood Cell in circulation 2-16 days
- Life span of White Blood Cell in body tissues 36 hours
- Leukocytes remain in storage in Bone Marrow: 80-90%
III. Interpretation: Normal Range White Blood Cells (in 10^9/L)
- Age 12 hours old: 13.0 to 38.0
- Age 2 weeks old: 5.0 to 20.0
- Age 6 Months to 2 years: 6.0 to 17.5 (Mean 11.0)
- Age 4 Years: 5.5 to 15.5 (Mean 9.1)
- Age 6 Years: 5.0 to 14.5 (Mean 8.5)
- Age 8 to 16 Years: 4.5 to 13.5 (Mean 8.1)
- Age over 21 Years: 4.5 to 11.0 (Mean 7.4)
- Third trimester: 5.8 to 13.2
- Postpartum: Up to 12.6
IV. Interpretation: Increased White Blood Cell Count
- See Leukocytosis
- Neutrophilia (>7000/mm3 or >60%, most common cause)
- Lymphocytosis (>4500/mm3 or >40% of total)
V. Interpretation: Decreased White Blood Cell Count (Leukopenia)
- Neutropenia (most common cause)
- Lymphocytopenia
- Monocytopenia
- Eosinopenia