Dr. Mohammed Hussein M.B.Ch.B, MSC, PhD, DCH (UK), MRCPCH BLOOD CELLS Part 1 Dr. Mohammed Hussein M.B.Ch.B, MSC, PhD, DCH (UK), MRCPCH 8:01 AM

Blood has four major elements: Red blood cells (Erythrocytes) RBC White blood cells (Leukocytes) WBC Platelets (Thrombocytes) Plasma 8:01 AM

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Bone Marrow Derived Stem Cells Haematopoietic Stem Cells (HSCs): can form all of the types of blood cells in the body. clinically for bone marrow transplants Mesenchymal Stem Cells: can generate bone, cartilage, fat, cells that support the formation of blood and fibrous connective tissue. clinically for regenerative medicine 8:01 AM

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Methods of Studying the Blood Cells 8:01 AM

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RED Blood Cells (ERYTHROCTES) RBCs are highly deformable and are specialized for carrying oxygen 8:01 AM

as this is lost during formation Bright pink-stained cells Anucleated as this is lost during formation Bright pink-stained cells due to the content of haemoglobin Biconcave shape Maximizes their surface area/volume ratio and thereby maximizes oxygen exchange 7.5 µm in diameter RBCs are highly deformable and are able to squeeze through small blood vessels down to 3–4 µm in diameter 3.9– 5.5 million /µL in women 4.1– 6 million /µL in men 8:01 AM

Metabolism Despite a lack of organelles, red cells are metabolically active and derive energy by: Anaerobic metabolism of glucose, and through ATP generation by the hexose monophosphate shunt 8:01 AM

Red Cell Membrane 8:01 AM

Actin/Spectrin-containing cytoskeletal meshwork Is largely responsible for maintaining the distinctive biconcave shape (maximizes their surface area/volume ratio and thereby maximizes oxygen exchange) Make RBCs highly deformable and are able to squeeze through small blood vessels down to 3–4 µm in diameter. 8:01 AM

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RBCs lifespan Red cells have a lifespan of 100–120 days in the circulation. The mature red cell is unable to synthesize new enzymes to replace those lost during normal metabolic processes. Destroyed in the spleen 8:01 AM

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KEY FACTS Have no cell organelles Contain haemoglobin Main function is O2 & CO2 transport Cell membrane is braced by an actin/spectrin-containing cytoskeleton which maintains shape. Biconcave shape for high surface area/volume ratio 8:01 AM

Hereditary Spherocytosis Defect in spectrin RBC shape is round and convex (no biconcave disc) Are abnormally brittle and less deformable than normal red cells Not pass easily through the splenic microcirculation They are trapped there and rapidly destroyed in large numbers (haemolysis) 8:01 AM

Sickle Cell Anaemia Point mutations in the haemoglobin gene may cause abnormal red cells. Precipitation of haemoglobin in red cells subject to hypoxia, which causes a sickle shape instead of the biconcave disc. Sickled cells become disrupted and can also block blood vessels. 8:01 AM

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Hypochromic, Microcytic Anaemia The most common cause of anemia is deficiency of iron, which is essential for the formation of hemoglobin. Red cells are released into the circulation containing much less hemoglobin than normal, and are therefore pale staining (hypochromic) and small (microcytic) 8:01 AM

Normal Hypochromic, Microcytic 8:01 AM

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