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Questions and Answers
What percentage of body weight does blood constitute?
What percentage of body weight does blood constitute?
Which of the following is NOT a function of blood?
Which of the following is NOT a function of blood?
What is the normal pH range of blood?
What is the normal pH range of blood?
Which component of blood constitutes about 55% of its composition?
Which component of blood constitutes about 55% of its composition?
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What is the viscosity of whole blood relative to water?
What is the viscosity of whole blood relative to water?
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Which of the following ions is primarily responsible for maintaining blood osmolarity?
Which of the following ions is primarily responsible for maintaining blood osmolarity?
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What is the specific gravity of blood?
What is the specific gravity of blood?
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What role do white blood cells play in blood function?
What role do white blood cells play in blood function?
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What percentage of blood is typically composed of plasma?
What percentage of blood is typically composed of plasma?
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Which plasma protein is mainly responsible for blood clotting?
Which plasma protein is mainly responsible for blood clotting?
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What is the typical haematocrit range for males?
What is the typical haematocrit range for males?
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What is the primary function of albumin in the blood?
What is the primary function of albumin in the blood?
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Which type of blood cell is responsible for carrying oxygen?
Which type of blood cell is responsible for carrying oxygen?
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What component of plasma is considered a major carrier for nutrients?
What component of plasma is considered a major carrier for nutrients?
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Which type of globulin is primarily associated with the immune response?
Which type of globulin is primarily associated with the immune response?
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What would likely cause an elevated haematocrit level?
What would likely cause an elevated haematocrit level?
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Study Notes
MD137 Haematology - Lecture 1
- Course: MD137 Haematology
- Lecture: 1, Functions & Composition of Blood
- Lecturer: Dr. Louise Horrigan, Physiology
- Email: [email protected]
Learning Objectives
- Blood functions
- Blood constituents
- Plasma characteristics
- Formed element characteristics
Functions of Blood
- Transport of O₂ and CO₂
- Transport of nutrients and waste
- Transport of hormones
- Maintenance of homeostasis
- Heat regulation
- Regulation of pH
- Immunity (white blood cells, antibodies)
- Haemostasis (blood clotting balance)
Properties of Blood
- Constitutes approximately 8% of body weight (Female 4-5L, Male 5-6L)
- pH: 7.35 - 7.45
- Osmolarity: 285 - 295 mOsm/L
- Viscosity: 3.5 – 5.5 times that of water (whole blood)
- Density/specific gravity: 1.05g/ml
- Composition: Formed elements (45%) and plasma (55%)
Blood Collection and Separation
- Blood collected in vacutainers with anticoagulants (EDTA, citrate, or heparin)
- Centrifugation separates blood into:
- Plasma (55% of total blood volume)
- Buffy coat (leukocytes & platelets, <1% of total blood)
- Erythrocytes (red blood cells, 45% of total blood)
Haematocrit (PCV)
- Percentage of blood occupied by red blood cells (RBCs)
- Normal values:
- Females: 0.37 - 0.47
- Males: 0.42 - 0.52
Constituents of Blood
-
Plasma: Approximately 55% of blood
- Water (91-93%)
- Proteins (6-8%)
- Other constituents (~1400 identified)
- Nutrients (glucose, lipids, amino acids)
- Nitrogenous wastes
- Gases
- Electrolytes
- Hormones
-
Formed elements: Approximately 45% of blood
- White blood cells (leukocytes)
- Red blood cells (erythrocytes)
- Platelets
Plasma Proteins
- Albumin: ~60% (contributes to viscosity, fluid balance, carrier for hormones/drugs)
- Globulins: ~36% (transport lipids, vitamins, hormones, antibodies)
- Fibrinogens: ~4% (blood clotting)
- Others: ~1% (regulatory proteins)
Formed Elements: Specifics
-
Erythrocytes (red blood cells):
- 4.3-5.9 million/µL (males)
- 3.5-5.5 million/µL (females)
-
Leukocytes (white blood cells):
- 4,500-11,000/µL
-
Thrombocytes (platelets):
- 150,000-400,000/µL
Thrombocytes (platelets)
- Arise from megakaryocytes
- 1 megakaryocyte releases over 1000 platelets
- 1.5-3µm in diameter
- No nucleus but have mitochondria
- Lifespan of approximately 10 days
- Intracellular granules hold proteins/factors
- Prevent blood loss
- Wound healing/blood vessel integrity
- Immune functions
Erythrocytes (red blood cells): Structure/Function
- Biconcave discs for large surface area of gas diffusion
- 6-8 µm in diameter, 2.5 µm thick
- Lack of a nucleus
- Lack of mitochondria (anaerobic energy production)
- Lifespan of 120 days
Erythrocytes: Functions
- Carriage of O₂ (99% bound to haemoglobin)
- Carriage of CO₂ (10% dissolved, 30% bound to plasma proteins, 60% as bicarbonate)
- Regulation of pH
Regulation of Blood pH (Bicarbonate System)
- Cytoplasm contains carbonic anhydrase
- Carbonic acid quickly dissociates into bicarbonate and hydrogen ions(CO₂ + H₂O ↔ H₂CO₃ ↔ HCO₃⁻ + H⁺)
- Principle of Le Chatelier: High CO₂ shifts to right, producing H⁺ ions
Regulation of Blood pH (Hemoglobin)
- Most H⁺ produced from carbonic acid binds to haemoglobin
- HCO₃⁻ can leave the cell to act as a buffer in the plasma.
- HCO₃⁻/Cl⁻ antiporter carries Cl⁻ into the cell and HCO₃⁻ out (chloride shift).
- Haemoglobin directly binds some CO₂
Leukocytes (White Blood Cells)
- Different types identified by size, shape of nucleus, and granularity.
- Differential white blood cell count (Total WBC count = 4,500 – 10,000 cells/µL)
- Different types are described (neutrophils, eosinophils, basophils, lymphocytes, and monocytes.)
Relative Abundance in Blood
Detailed percentages of types of leukocytes in the blood.
Granulocytes vs. Agranulocytes
- Granulocytes contain granules
- Agranulocytes do not contain granules
Neutrophils
- Large cells (2-3 days)
- Primary function is phagocytosis
- Travel quickly from blood to infection site
- Present in tissue during acute inflammation
Eosinophils, Basophils, Lymphocytes, and Monocytes
- Specific functions and characteristics for each
Summary of Main Points
- Blood performs many functions besides oxygen and carbon dioxide transport
- Properties of blood (pH, osmolarity) are tightly regulated
- Blood composed of formed elements (45%) and plasma (55%)
- Hematocrit is the proportion of blood occupied by erythrocytes (higher in males)
- Plasma composed of water, proteins & other constituents
- Plasma proteins important in transport and fluid balance
- RBCs have structure for O2 and CO2 transport, pH regulation
- WBCs play a role in immune defense
- Platelets are essential in blood clotting
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Description
Explore the foundational concepts of blood in this first lecture of the MD137 Haematology course. Learn about the various functions and composition of blood, including the characteristics of plasma and formed elements. This quiz will test your knowledge on blood transport mechanisms and its vital properties.
