Histological Structure of Blood Cells Part I PDF

# Histological Structure of Blood Cells Part I ## Dr. Amal Abd El-hafez Associate Professor of Histopathology ## Learning Objectives By the end of this lecture, you will be able to: 1. List the different components of blood. 2. Explain how to prepare a blood film and bone marrow biopsy. 3. Descri...

# Histological Structure of Blood Cells Part I ## Dr. Amal Abd El-hafez Associate Professor of Histopathology ## Learning Objectives By the end of this lecture, you will be able to: 1. List the different components of blood. 2. Explain how to prepare a blood film and bone marrow biopsy. 3. Describe the normal structure of mature RBCs and associated abnormalities. ## Blood ### Introduction - Definition: Blood is a sticky red fluid that flows in a closed circulatory system - Volume: about 5.5 liters in the human body. - PH 7.4 (slightly alkaline) - Composition: - Liquid = Plasma - Formed elements = Blood cells: - Erythrocytes (red blood cells) - Leukocytes (white blood cells) - Platelets ## Blood Smear - Image of a blood smear showing different cells: red blood cells, platelets, neutrophils, monocytes, and lymphocytes. ## Functions of Blood 1. Transport of gases, nutrients, waste products, hormones, electrolytes, and many other materials inside the body. 2. Regulation of PH. 3. Regulation of osmotic pressure. 4. Regulation of body temperature. 5. Protection and immunity. 6. Clot formation. # I- Plasma and Plasma Proteins ## Liquid Part of Blood - Pale yellow fluid: - 91% water - 7-8% proteins (albumin, globulins, fibrinogen) - 1% electrolytes, glucose, gases, and other. ## Proteins: - Albumin - Globulins - Lipoproteins - Fibrinogen - Prothrombin # II- Blood Cells = Formed elements - 95% red blood cells - 5% white blood cells - Platelets (thrombocytes) - Granulocytes - Neutrophils - Eosinophils - Basophils - Agranulocytes - Lymphocytes - Monocytes # Study of Blood Cells & Bone Marrow - Blood cells are studied in smears or films. - Smears or films: Spreading of a drop of blood in a thin layer on a microscope slide + drying + alcohol fixation. - Blood smears are routinely stained with mixtures of acidic and basic dyes. - Such as, Giemsa, Wright's, Leishman's stains. - Aim: visualization of cell nuclei (basophilia) and cytoplasmic granules (Azurophilia, Eosinophilia, Neutrophilia) - Bone marrow samples are obtained from iliac crest and stained with Hematoxylin & Eosin (H&E). - Image depicting a procedure for bone marrow biopsy # Blood Smear Preparation - Image of a blood smear (microscopic view) - Image of a bone marrow section (microscopic view) # Erythrocytes (Red Blood Cells = Red Blood Corpuscles = RBCs) - Erythrocytes are biconcave anucleate discs with central pallor. - Size: 7-7.5 micrometer - Development: From pro-erythrocytes in bone marrow. - Life span: about 120 days. - Removal: by macrophages of the spleen, liver, and bone marrow. - Blood count of RBCs: About 4-6 million per microliter. - Images of RBCs viewed from the side and top, and a scanning EM image. ## Structure of RBCs - No nuclei, no organelles. - Contains normal adult hemoglobin (HbA) - The erythrocyte is flexible, to adapt to small capillaries. - Surrounded by a cell membrane: (phospholipids, cholesterol, glycolipids, protein, and carbohydrate). - The erythrocyte membrane contains a protein named spectrin. ## Spectrin: - Supports the erythrocyte membrane. - Gives the flexibility of the membrane. ## Function of RBCs: - O2 and CO2 transport (gas exchange) # Hematocrit Value - A valuable clinical test performed by centrifugation of a heparinized blood sample in a test tube. - The result: 3 layers typically appear in the tube after centrifuge, a top layer (plasma), middle layer (buffy coat), and the basal layer (packed red blood cells). - The basal layer represents the hematocrit value. ## Hematocrit Value: - Is an estimate of the volume of packed erythrocytes (RBCs) per unit volume of blood when centrifuged. - Normal hematocrit: - Males = 40-50% - Women = 35 - 45% - Image depicting a hematocrit experiment. # Disorders of RBCs 1. Anemia: decreased number/size of erythrocytes or decreased total hemoglobin content in the blood. 2. Erythrocytosis & Polycythemia: An increased number of erythrocytes. 3. Macrocytes: Erythrocytes with diameters greater than 9 micrometer, caused by folic acid or vitamin B12 deficiency. 4. Microcytes: with diameters less than 6 micrometer, caused by iron deficiency. 5. Aplastic Anemia: bone marrow failure. 6. Hemolytic Anemia: Inherited genetic alterations in RBCs or autoimmune. 7. Reticulocytosis: increase number of reticulocytes in blood due to rapid blood loss. Normal range, 0.5 - 1.5%. 8. Poikilocytosis: increase in the number of distorted RBCs. # Recommended Reference, Website - Wheater's Functional Histology: A Text and Color Atlas, 6th Edition. - ISBN-13: 978-0702047473 - ISBN-10: 0702047473 - The histology tutor: http://www2.yvcc.edu/histology zoomer/HistologyTutorials/histology_tutorials.htm