Hematology-I

  PART A: ERYTHROCYTES 4.1 Definition of Erythrocytes Erythrocytes , commonly known as red blood cells (RBCs), are specialized blood cells responsible primarily for transporting oxygen from the lungs to body tissues and participating in carbon dioxide transport from tissues to the lungs. Mature human erythrocytes have a distinctive biconcave disc shape. They lack a nucleus and most intracellular organelles, providing more space for hemoglobin and enabling considerable cellular deformability. General characteristics of mature erythrocytes Characteristic Description Shape Biconcave disc Diameter Approximately 7–8 µm Thickness Approximately 2–2.5 µm at the periphery and about 1 µm centrally Nucleus Absent Mitochondria Absent Main intracellular protein Hemoglobin Energy production Primarily anaerobic glycolysis Average lifespan Approximately 120 days Main site of production Red bone marrow Main site of removal Macrophages in the spleen, liver, and bone marrow Why are erythrocytes bicon...

3.1 Introduction to Hematopoiesis Hematopoiesis is the continuous physiological process through which all blood cells are produced, developed, matured, and released into the circulation. The major mature blood-cell populations produced by hematopoiesis are:  Erythrocytes (RBCs),  Leukocytes (WBCs), and  Platelets Although mature blood cells perform very different functions, they originate from a common population of hematopoietic stem cells (HSCs) . 3.2 Hematopoietic Stem Cells Definition A hematopoietic stem cell (HSC) is an immature blood-forming cell capable of: Self-renewal Differentiation into multiple blood-cell lineages Self-renewal Self-renewal allows the stem-cell population to maintain itself throughout life. Differentiation Differentiation is the process through which an immature stem/progenitor cell becomes progressively specialized. For example: HSC ↓ Myeloid progenitor ↓ Erythroid progenitor ↓ Erythroblast ↓ Reticulocyte ↓ Mature RBC 3.3 Origin and De...