BUNDLE 4: BLOOD & HEMATOLOGY
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INTRODUCTION
Blood is a connective tissue. It is also regarded as an organ in fluid state.
• Constitutes **7% of body weight** (~5.6 litres in a 70 kg man)
• Proportion is less in women, greater in children
• Blood in vessels is always in motion
• Volume and concentration kept within narrow limits by control systems (homeostasis)
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FUNCTIONS OF BLOOD
1. **Transports:**
• Oxygen and carbon dioxide
• Nutrients from alimentary tract to tissues
• Cell waste materials to excretory organs
• Hormones to target sites
2. **Protection** of the body against infections
3. **Distributes heat**
4. Carries materials involved in **blood clotting**
5. Maintains **acid-base balance** using blood proteins and buffers (e.g., bicarbonate)
6. Maintains **adequate fluid volume** (NaCl, albumin prevent excessive fluid loss)
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COMPOSITION OF BLOOD
Component Percentage
Plasma 55%
Formed elements (cells and cell 40-45%
fragments)
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PLASMA
Constituents:
Water: 90-92%
Dissolved substances:
, Plasma Proteins (7%)
Formed in liver (except immunoglobulins):
• **Albumin**: Most abundant; maintains normal plasma osmotic pressure; carrier for
free fatty acids and steroid hormones
• **Globulin**: Antibodies (immunoglobulins); transports some hormones; inhibits
proteolytic enzymes
• **Clotting factors**: Help in clotting process
Inorganic Salts/Electrolytes
NaCl, NaHCO3, Mg, P, Fe, Ca, Cu, Iodine, Cobalt
Nutrients
Monosaccharides, amino acids, fatty acids, glycerol, vitamins
Organic Waste Materials
Urea, uric acid, creatinine
Other Components
Hormones, enzymes, gases (O2, CO2, N2)
Note: Plasma lacking clotting factors is called serum.
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FORMED ELEMENTS (CELLS)
7. **Erythrocytes** — Red Blood Cells (RBC)
8. **Leukocytes** — White Blood Cells (WBC)
9. **Thrombocytes** — Platelets
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ERYTHROCYTES (RBC)
Main function: Gas transport
Characteristics:
• Circular, biconcave, non-nucleated discs
• Increase surface area for gas transport
• Flexible (squeeze through narrow capillaries)
• No intracellular organelles (more room for hemoglobin)
DEVELOPMENT AND LIFESPAN
• Formed in **red bone marrow**
• Lifespan in circulation: **~120 days**
• Development takes ~7 days:
• Maturation of cell
__________________________________________________
INTRODUCTION
Blood is a connective tissue. It is also regarded as an organ in fluid state.
• Constitutes **7% of body weight** (~5.6 litres in a 70 kg man)
• Proportion is less in women, greater in children
• Blood in vessels is always in motion
• Volume and concentration kept within narrow limits by control systems (homeostasis)
__________________________________________________
FUNCTIONS OF BLOOD
1. **Transports:**
• Oxygen and carbon dioxide
• Nutrients from alimentary tract to tissues
• Cell waste materials to excretory organs
• Hormones to target sites
2. **Protection** of the body against infections
3. **Distributes heat**
4. Carries materials involved in **blood clotting**
5. Maintains **acid-base balance** using blood proteins and buffers (e.g., bicarbonate)
6. Maintains **adequate fluid volume** (NaCl, albumin prevent excessive fluid loss)
__________________________________________________
COMPOSITION OF BLOOD
Component Percentage
Plasma 55%
Formed elements (cells and cell 40-45%
fragments)
__________________________________________________
PLASMA
Constituents:
Water: 90-92%
Dissolved substances:
, Plasma Proteins (7%)
Formed in liver (except immunoglobulins):
• **Albumin**: Most abundant; maintains normal plasma osmotic pressure; carrier for
free fatty acids and steroid hormones
• **Globulin**: Antibodies (immunoglobulins); transports some hormones; inhibits
proteolytic enzymes
• **Clotting factors**: Help in clotting process
Inorganic Salts/Electrolytes
NaCl, NaHCO3, Mg, P, Fe, Ca, Cu, Iodine, Cobalt
Nutrients
Monosaccharides, amino acids, fatty acids, glycerol, vitamins
Organic Waste Materials
Urea, uric acid, creatinine
Other Components
Hormones, enzymes, gases (O2, CO2, N2)
Note: Plasma lacking clotting factors is called serum.
__________________________________________________
FORMED ELEMENTS (CELLS)
7. **Erythrocytes** — Red Blood Cells (RBC)
8. **Leukocytes** — White Blood Cells (WBC)
9. **Thrombocytes** — Platelets
__________________________________________________
ERYTHROCYTES (RBC)
Main function: Gas transport
Characteristics:
• Circular, biconcave, non-nucleated discs
• Increase surface area for gas transport
• Flexible (squeeze through narrow capillaries)
• No intracellular organelles (more room for hemoglobin)
DEVELOPMENT AND LIFESPAN
• Formed in **red bone marrow**
• Lifespan in circulation: **~120 days**
• Development takes ~7 days:
• Maturation of cell
