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Questions and Answers
What is the primary function of red blood cells?
What is the primary function of red blood cells?
At what stage does haemopoiesis primarily occur in the bone marrow for adults?
At what stage does haemopoiesis primarily occur in the bone marrow for adults?
Which type of white blood cells includes neutrophils, basophils, and eosinophils?
Which type of white blood cells includes neutrophils, basophils, and eosinophils?
What characterizes anaemia?
What characterizes anaemia?
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Which part of the blood contains electrolytes, hormones, and proteins?
Which part of the blood contains electrolytes, hormones, and proteins?
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What is a characteristic feature of microcytic hypochromic anaemia?
What is a characteristic feature of microcytic hypochromic anaemia?
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Which condition is closely associated with macrocytic anaemia?
Which condition is closely associated with macrocytic anaemia?
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What is NOT a common clinical feature of anaemia?
What is NOT a common clinical feature of anaemia?
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What is a potential cause of iron deficiency anaemia?
What is a potential cause of iron deficiency anaemia?
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Which investigation is NOT typically performed for iron deficiency anaemia?
Which investigation is NOT typically performed for iron deficiency anaemia?
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What is a critical step in the venepuncture process?
What is a critical step in the venepuncture process?
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Which of the following is NOT a cause of reduced iron absorption?
Which of the following is NOT a cause of reduced iron absorption?
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In which scenario is point of care testing (P.O.C.T.) most commonly used?
In which scenario is point of care testing (P.O.C.T.) most commonly used?
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What is the recommended management for iron deficiency anaemia?
What is the recommended management for iron deficiency anaemia?
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Which of the following red blood cell indices indicates macrocytic anaemia?
Which of the following red blood cell indices indicates macrocytic anaemia?
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Study Notes
Introduction to Haematology
- Haematology is the study of blood and blood-forming organs.
What is Blood
- Blood is a complex fluid connective tissue.
Centrifugation of Anticoagulated Blood
- Centrifuging anticoagulated blood separates it into layers:
- Plasma: The liquid portion.
- Buffy Coat: Contains white blood cells (WBCs) and platelets.
- Red Cells: Predominantly erythrocytes.
Haemopoiesis
- Blood volume in a typical adult is approximately 7% of body weight (70 ml/kg).
- Blood is composed of 45% cellular elements (erythrocytes, leukocytes, thrombocytes), and 55% plasma.
- Plasma contains water, proteins, electrolytes, hormones, substances from the gastrointestinal (GI) tract, and metabolic products.
Haemopoiesis (Lifespan)
- All blood cells have a finite lifespan.
- Red blood cells (RBCs): ~120 days.
- White blood cells (WBCs): 4 hours to 10 years.
- Platelets (PLTs): 10-14 days.
- Cell loss occurs due to ageing, physiological consumption, and loss from the body.
Sites of Haemopoiesis
-
Foetus:
- 0-2 months: Yolk sac
- 2-7 months: Liver and spleen
- 5-9 months: Bone marrow
- Infants: Bone marrow (all bones)
- Adults: Bone marrow (vertebrae, ribs, sternum, skull, sacrum, pelvis, proximal ends of femurs)
Haemopoietic Stem and Progenitor Cells
- Blood cell production begins with pluripotent stem cells.
- These cells differentiate into various progenitor cells, including erythroid, myeloid, and lymphoid lineages.
- These progenitors then develop into mature blood cells. (Diagram)
Normal Peripheral Blood Cells - Erythrocytes
- Red blood cells (RBCs) are circular, biconcave discs, ~8 µm in diameter.
- Their shape and surface-to-volume ratio facilitate optimal gas exchange.
- RBCs are easily deformable, allowing passage through small capillaries.
Normal Peripheral Blood Cells - Leukocytes
- Leukocytes are the white blood cells.
- Granulocytes:
- Neutrophils
- Eosinophils
- Basophils
- Other white blood cells:
- Monocytes
- Lymphocytes (B-cells, T-cells)
- Granulocytes:
Normal Peripheral Blood Cells - Platelets
- Platelets are essential for haemostasis.
Haemoglobin - Synthesis and Structure
- The main function of red blood cells is to carry oxygen to tissues and return carbon dioxide to the lungs.
- Haemoglobin (Hb) is a specialized protein for this task; each red cell contains nearly 640 million Hb molecules.
- Hb consists of four globin polypeptide chains, each with a haem group.
- The haem group contains iron, crucial for oxygen binding. (Chemical structure of Heme)
What is Anemia
- Anemia is a reduction in the oxygen-carrying capacity of the blood due to lower-than-normal haemoglobin concentration.
- Haemoglobin concentrations vary within healthy populations.
- Anemia occurs when red blood cell destruction exceeds red blood cell production.
Anemia - Classification
- Classified by the size and colour of red blood cells.
- Microcytic hypochromic (MCV < 80 fl, MCH < 27 pg): Iron deficiency, thalassaemia, lead poisoning.
- Normocytic normochromic (MCV 80-95 fl, MCH = 26 pg): Haemolytic anaemia, acute blood loss, renal disease.
- Macrocytic (MCV > 95 fl): Megaloblastic anaemia, alcohol, liver disease
Blood Film - Red Cell Morphology
(List of red blood cell abnormalities, causes, and microscopic images and descriptions)
Clinical Features of Anemia
- Symptoms of anemia include tachycardia, shortness of breath, weakness, lethargy, palpitations, headaches, confusion, pallor of conjunctival mucosa and nail beds, and retinal haemorrhages.
Causes of Iron Deficiency Anemia
- Increased demand (growth, pregnancy, lactation)
- Depletion of iron stores
- Blood loss (physiological or pathological)
- Reduced absorption (dietary deficiency or malabsorption)
Iron Deficiency Anemia
- Stages of iron deficiency:
- Normal
- Latent iron deficiency
- Iron deficiency anaemia
Investigation of IDA
- Methods used to diagnose iron deficiency anaemia, including red blood cell indices, blood film, bone marrow iron, serum iron, and ferritin.
Treatment for IDA
- Treat the underlying cause.
- Administer oral iron supplements.
Blood Samples
- Samples can be capillary (finger prick) or venous.
- Venous samples are typically collected using vacutainer tubes from antecubital vein.
Venepuncture
- Safety procedures for blood collection, including identification, consent, correct anticoagulants, and sample volume.
- Types of blood samples: serum (clotting), and plasma (anticoagulated samples).
- Anticoagulants and collection system used in Haematology.
Bone Marrow
- Used to examine cellular morphology, particularly for lymphoproliferative disorders and haematological disease.
- Collected using bone marrow aspiration or biopsy.
Point of Care Testing
- Used in primary health care and acute wards (e.g., ITU, A&E).
- Useful in rural healthcare settings.
- Important for instrument calibration and quality control.
The 'Full Blood Count'
- A key haematology test.
- Measures haemoglobin level, white blood cell count (including automated differential), red blood cell count, platelet count, and red cell parameters.
Laboratory Aspects - FBC
- Full blood count (FBC) is the first-line test in haematology.
- Automated methods are highly accurate and precise.
- Instrument flags indicate aberrant results.
Normal Haematological Values
- Reference ranges for neutrophils, lymphocytes, monocytes, eosinophils, and basophils. (Table of values)
Manual Spreading of Blood Smear
- Technique for preparing blood smears for microscopic examination.
Blood and Bone Marrow Smears
- Diagrams comparing stained and unstained blood and bone marrow smears.
Blood Film Smear Review By Microscopy
- Procedure for reviewing blood films under a microscope.
White Blood Cells
- Types of white blood cells: Phagocytes (granulocytes, monocytes) and immunocytes (lymphocytes, plasma cells).
Monocytes
- Monocytes circulate briefly in the bone marrow, then mature into macrophages within tissues.
- These macrophages perform various functions in different tissues.
Neutrophil and Monocyte Function
- Chemotaxis: Cells move towards sites of inflammation or infection in response to chemical signals.
- Phagocytosis: Cells ingest and destroy foreign particles or damaged host cells.
Phagocytosis and Bacterial Destruction
- Mechanism of bacterial destruction by neutrophils and macrophages. (Diagram)
Neutropenia
- Neutropenia: Low neutrophil count, increasing risk of infection.
- Causes of neutropenia can be varied.
Lymphocytes
- Lymphocytes are responsible for the body's immune response.
- Types of lymphocytes: B-cells, T-cells.
- Different types of lymphocytes express different proteins like CD4 and CD8.
Lymphocytosis
- High lymphocyte count, usually associated with infection in children.
Infectious Mononucleosis
- Acute illness, often called glandular fever.
- Caused by the Epstein-Barr virus.
- Characterized by sore throat, lymphadenopathy, and fever.
Haemostasis
- Mechanism for stopping bleeding and preventing excessive clotting and breakdown of clots once repair is accomplished.
Components of Haemostasis
- Blood components supporting haemostasis: Platelets, coagulation factors, inhibitors, fibrinolysis, blood vessels.
Platelets
- Platelets are produced in bone marrow by fragmentation of megakaryocytes.
- Platelet production is regulated by thrombopoietin.
Platelet Production
- Sequence of events from megakaryocyte to the production of platelets. (Diagram)
Coagulation
- Coagulation process initiation and amplification.
- Factors involved: Tissue factor, Activated factors, Thrombin, Vit K dependent factors.
Haemostatic Response
(Diagram illustrating the haemostatic process)
Coagulation and Bleeding Disorders
- Thrombocytopenia: Low platelet count, leading to skin purpura and prolonged bleeding.
- Causes of thrombocytopenia can be varied.
Thrombocytopenia
- Images showing symptoms of thrombocytopenia.
Coagulation Disorders - Haemophilia A
- Most common hereditary clotting factor deficiency (30-100 / million population).
- Sex-linked trait impacting factor VIII level, causing spontaneous bleeding, especially in joints (and following trauma).
- Deficiency often is inherited.
Clinical Features - Haemophilia A
- Symptoms of haemophilia A - excessive bleeding (e.g., in post-circumcision infants), and bruising, particularly in joints.
VIII Activity and Disease Severity
- Relationship between factor VIII activity levels and disease severity.
Family Tree
- Patterns of inheritance within a family exhibiting haemophilia A, showing carrier status and affected individuals.
Treatment - Haemophilia A
- Management of haemophilia A; treatment regimens and genetic therapy's role.
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Description
Test your knowledge of human blood components and their functions with this quiz. Explore key topics including red blood cells, white blood cells, and the process of haemopoiesis. Perfect for students studying human biology or health sciences.
