Important points for mcqs
Here are the high-yield MCQ points from this hematology page:
🔴 Erythrocytes (RBCs)
| Feature | Detail |
|---|---|
| Function | Carry O₂ to tissues, CO₂ to lungs |
| Structure | Anucleate, biconcave, no organelles |
| Lifespan | ~120 days (adults); 60–90 days (neonates) |
| Energy source | Glucose — 90% glycolysis, 10% HMP shunt |
| Key transporter | Cl⁻/HCO₃⁻ antiporter (exports HCO₃⁻, transports CO₂ to lungs) |
| Destruction site | Spleen (also 1/3 of platelet pool stored here) |
Terminology:
- Erythrocytosis = ↑ Hct (polycythemia)
- Anisocytosis = varying sizes
- Poikilocytosis = varying shapes
- Reticulocyte = immature RBC; reflects erythroid proliferation; bluish (polychromasia) on Wright-Giemsa = residual ribosomal RNA
🟣 Thrombocytes (Platelets)
| Feature | Detail |
|---|---|
| Structure | Anucleate, small cytoplasmic fragments |
| Origin | Derived from megakaryocytes |
| Lifespan | 8–10 days |
| Storage | 1/3 of pool stored in spleen |
| Activation trigger | Endothelial injury |
| Role | Involved in 1° hemostasis |
Granule contents:
- Dense granules: Ca²⁺, ADP, Serotonin, Histamine — mnemonic CASH
- α granules: vWF, fibrinogen, fibronectin, platelet factor 4
Key receptors:
- vWF receptor → GpIb
- Fibrinogen receptor → GpIIb/IIIa
- Thrombopoietin → stimulates megakaryocyte proliferation (produced by liver & kidney)
- Thrombocytopenia or ↓ platelet function → petechiae
🟡 Monocytes
| Feature | Detail |
|---|---|
| Nucleus | Large, kidney-shaped |
| Cytoplasm | Extensive "frosted glass" appearance |
| Differentiate into | Macrophages or dendritic cells in tissues |
🟤 Macrophages
| Feature | Detail |
|---|---|
| Activation | IFN-γ |
| Function | APC via MHC II; phagocytosis; antibody-dependent cellular cytotoxicity |
| Granulomas | Key cellular component (e.g., TB, sarcoidosis) — may fuse to form giant cells |
| Septic shock trigger | Lipid A from bacterial LPS binds CD14 on macrophages |
Tissue-specific names:
- Liver → Kupffer cells
- Connective tissue → Histiocytes
- Bone → Osteoclasts
- Brain → Microglial cells
⚡ Top MCQ Traps
- RBC energy = glucose; 90% glycolysis, 10% HMP shunt
- Platelet vWF receptor = GpIb (not IIb/IIIa — that's fibrinogen)
- Reticulocyte polychromasia = residual rRNA, not DNA
- Macrophages activated by IFN-γ, present via MHC II
- Lipid A + CD14 → septic shock mechanism
- Thrombopoietin source = liver & kidney
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