Notes on BLOOD for NEET, AIIMS, JIPMER, INICET

Comprehensive Notes on BLOOD
For NEET, AIIMS, JIPMER, INI-CET, FMGE

1. General Introduction

• Blood is a fluid connective tissue
• Volume: Adult male → 5–6 L (70–80 mL/kg) | Female → 4.5–5.5 L | Newborn → 85–90 mL/kg
• pH: 7.35–7.45 (average 7.4)
• Specific gravity: 1.050–1.060 | Viscosity: 4–5 × water
• Blood is a non-Newtonian fluid

2. Composition of Blood

Component	Percentage	Main Constituents
Plasma	55%	Water 91–92%, Proteins 7–8%, others
Formed elements	45%	RBC > Platelets > WBC

3. Plasma Proteins (6–8 g/dL)

Protein	Normal (g/dL)	Functions	Synthesis
Albumin	3.5–5.0	Oncotic pressure, transport	Liver
Globulins	2.0–3.5	Immunity (γ), transport (α,β)	Liver + Plasma cells
Fibrinogen	0.2–0.4	Clotting	Liver
A/G ratio	1.2 : 1 to 1.6 : 1	↓ in liver disease, nephrotic syndrome

4. Red Blood Cells (Erythrocytes)

Parameter	Male	Female
RBC count	4.7–6.1 million/μL	4.2–5.4 million/μL
Hemoglobin	13–17 g/dL	12–15 g/dL
Hematocrit (PCV)	40–50%	36–46%
MCV	82–98 fL
MCH	27–32pg
MCHC	32–36 g/dL
RDW	11.5–14.5%
Reticulocyte count	0.5–1.5%
ESR (Wintrobe)	0–9 mm/hr	0–20 mm/hr

Life span of RBC → 120 days | Daily destruction ≈ 1% (10¹¹ RBCs/day)

5. Hemoglobin Structure & Types

• Adult: HbA (α₂β₂) 95–97%, HbA₂ (α₂δ₂) 2–3%, HbF <1%
• Fetal Hb (HbF = α₂γ₂) → Higher O₂ affinity, resistant to 2,3-BPG
• 1 g Hb binds 1.34 mL O₂
• Total O₂ carrying capacity = Hb × 1.34 × saturation

6. Oxygen & CO₂ Transport

Oxygen Transport

• 97% as oxyhemoglobin, 3% dissolved
• P50 = 26–27 mmHg
• Oxygen dissociation curve – Sigmoid (cooperative binding)
• Right shift (↓ affinity): ↑CO₂, ↓pH, ↑2,3-BPG, ↑temp, HbS
• Left shift (↑ affinity): HbF, CO, alkalosis, ↓2,3-BPG

CO₂ Transport

Form	Percentage
Dissolved	7%
Carbamino compounds	23%
Bicarbonate	70%

Chloride shift (Hamburger phenomenon) & Haldane effect are most important

7. Blood Buffers (Very High-Yield)

Buffer	Ratio at pH 7.4	Contribution
Bicarbonate	20 : 1	60–70%
Hemoglobin	—	Major intracellular
Plasma proteins	—	Minor
Phosphate	4 : 1	Important in urine

Henderson-Hasselbalch: pH = 6.1 + log([HCO₃⁻] / 0.03 × PCO₂)

8. Acid-Base Disorders

Disorder	pH	Primary Change	Compensation
Metabolic acidosis	↓	↓ HCO₃⁻	↓ PCO₂
Metabolic alkalosis	↑	↑ HCO₃⁻	↑ PCO₂
Respiratory acidosis	↓	↑ PCO₂	↑ HCO₃⁻
Respiratory alkalosis	↑	↓ PCO₂	↓ HCO₃⁻

9. Blood Coagulation Cascade

Pathway	Trigger	Key Factors	Test
Intrinsic	Contact	XII → XI → IX → VIII → X	aPTT
Extrinsic	Tissue factor	VII → X	PT/INR
Common	—	X → V → II → I	Both

Vitamin K dependent factors: II, VII, IX, X, Protein C & S (γ-carboxylation of glutamic acid)

10. Important Clotting Factors Names

• Factor VIII → Anti-hemophilic factor (Hemophilia A)
• Factor IX → Christmas factor (Hemophilia B)
• Factor I → Fibrinogen
• Factor XIII → Fibrin stabilizing factor

11. Lab Anticoagulants

Anticoagulant	Use	Mechanism
EDTA	CBC	Irreversible Ca²⁺ chelation
Sodium citrate	PT, aPTT	Reversible Ca²⁺ chelation
Heparin	ABG, in vivo	Activates antithrombin III
Double oxalate	(Old) (ESR)	Ca²⁺ precipitation

12. Types of Anemia (Most Important Table)

Type	MCV	Key Features	Cause/Example
Iron deficiency	↓	Microcytic, ↑RDW, ↓ferritin	Blood loss, hookworm
Thalassemia	↓	Microcytic, normal RDW	Genetic
Megaloblastic	↑	Macro-ovalocytes, hypersegmented neutrophils	B12/folate deficiency
Sickle cell	Normal	Sickle cells, target cells	HbS (Glu→Val β6)
Sideroblastic	↓/dimorphic	Ring sideroblasts, ↑ferritin, ↑ serum iron	Lead, alcohol, MDS
Aplastic	Normal	Pancytopenia, empty marrow	Drugs, virus, idiopathic
Hemolytic	Normal/↑	↑ Reticulocytes, ↑ indirect bilirubin, ↑ LDH	Autoimmune, G6PD, spherocytosis
Anemia of chronic disease	Normal/↓	↑ Ferritin, ↓ TIBC, ↑ hepcidin	Infection, inflammation, malignancy

13. Must-Know Normal Values

Serum Na⁺	135–145 mEq/L
Serum K⁺	3.5–5.0 mEq/L
Serum Ca²⁺	8.5–10.5 mg/dL
Blood glucose (fasting)	70–99 mg/dL
Blood urea	20–40 mg/dL
Serum creatinine	0.6–1.2 mg/dL
Total bilirubin	0.3–1.2 mg/dL
Direct bilirubin	0.1–0.4 mg/dL

Final Tip: Revise this page 3–4 times + draw oxygen dissociation curve & coagulation cascade → you will score full marks in all blood-related questions in NEET/AIIMS!

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In the last 5 years, every single exam had at least ONE question each from:
→ Oxygen dissociation curve shifts
→ Fetal vs Adult Hemoglobin Curve
→ CO₂ Dissociation Curve
→ Coagulation cascade
→ Chloride shift
→ Acid-base disorders
Memorize these 6 diagrams → Guaranteed 8–12 marks!

Must Read: Blood MCQs asked in NEET, AIIMS, JIPMER, INICET