Blood Composition: Plasma, Cells & Key Proteins

Whole Blood ≈ 55% Plasma + 45% Formed Elements (Hematocrit)

Plasma (Acellular Matrix)

• Water: ~90%
• Proteins (7%):
  • Albumin (60%) – oncotic pressure, transport.
  • Globulins (α, β, γ) – transport, complement, immunoglobulins.
  • Fibrinogen (4%) – clotting.
• Other Solutes: Electrolytes (Na⁺, K⁺, Ca²⁺, Cl⁻, HCO₃⁻), nutrients (glucose, lipids, amino acids), hormones, waste (urea, creatinine), gases (O₂, CO₂).

Formed Elements (Cellular)

• Erythrocytes (RBCs): O₂/CO₂ transport via hemoglobin. No nucleus. ~5M/µL.
• Leukocytes (WBCs): Immune defense. 5 types (neutrophil, lymphocyte, monocyte, eosinophil, basophil). ~7K/µL.
• Thrombocytes (Platelets): Hemostasis. Fragments. 150–450K/µL.

Centrifuged Layers

1. Plasma (top, straw)
2. Buffy coat (thin, white – WBCs + platelets)
3. Packed RBCs (bottom, red)