RBC and erythropoiesis
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The document provides a comprehensive overview of erythropoiesis, detailing the stages of red blood cell (RBC) formation, their structure, and functions, as well as the regulation and influencing factors such as erythropoietin. It describes the lifespan, normal counts, and metabolic processes of RBCs, highlighting the importance of various hormones and dietary factors in erythropoiesis. Additionally, it mentions conditions affecting RBC counts, emphasizing the clinical implication of anemia.
![UNIVERSITY ASKED QUESTIONS
• Define erythropoiesis. Describe the stages of erythropoiesis and
identify the factors influencing it 10m [1+7+2]
• Outline the steps of erythropoiesis. Explain the essential factors
for it? [july-aug-2014].4m
• Erythropoiesis 4m [July; 2012]
• Erythropoietin 2m [july-2010]](https://image.slidesharecdn.com/rbceop-161202134846/85/RBC-and-erythropoiesis-33-320.jpg)
RBC and erythropoiesis
- 1. Erythropoiesi s Dr. K. Ambareesha., PhD (Med. Physio) Assit. Professor, Department of Physiology MNR Medical College & Hospital, Sangareddy, Telangana, India.
- 2. CONTENTS • INTRODUCTION TO RBC – • Structure, Functions, Normal count, Variations in size, shape and structure. • HAEMOPOIESIS • ERYTHROPOIESIS- • Stages and its Regulation
- 3. ERYTHROCYTES Surface area is 120 µ2. Normal volume is 80- 94 µ3. Normal life span of an RBC is 120 days.
- 4. ERYTHROCYTES Normal Erythrocyte Count Males 5-5.5 million cells/mm3 Females 4.5-5 million cells/mm3 Infants 6 – 7 million cells/mm3
- 5. STRUCTURE OF RBC • Lipids: Cholesterol, phospholipid, and glycolipids • Proteins: Spectrin, actin, ankyrin. • The glycolipids: constitute the ABO blood group substances (agglutinogens).
- 6. Metabolism Of RBC It is met by the glucose metabolism through the anaerobic Embden- Meyerhof (EMF) pathway (90%) and the pentose phosphate shunt (10%).
- 7. FUNCTIONS OF RBC • Transport of oxygen from lungs to tissues. • Transport of Co2 from tissues to lungs. • Regulation of acid-base balance.
- 8. ERYTHROPOIESIS Erythropoiesis is the process of formation of RBCs. Till 3rd week of intrauterine life in the mesoderm of the yolk sac. From the third month erythropoiesis takes place in the liver and spleen. After the fifth intrauterine life, the fetal bone marrow starts producing RBCs.
- 9. BONE MARROW Red bone marrow 1. At birth, it is present in all the bones. 2. In adults, it is present in flat bones (membranous bones) like cranial bones, vertebrae, pelvic bones, ribs, sternum, and upper ends of long bones like femur and humerus. Yellow bone marrow 1. is mainly made up of adipose (fat) tissue
- 12. PLURIPOTENT STEM CELLS This differentiates to form the committed stem cell. The committed stem cell of the myeloid series gives rise to all blood cells except the lymphocytes. *The committed stem cells for the erythrocyte give rise to the progenitor cells.
- 13. PROGENITOR CELLS BFU-E (burst-forming units) The development of Large colonies requires the presence of factors called burst-promoting activity (BPA). The cells are immature blast cells oval in shape with moderately basophilic cytoplasm, occasional pseudopods, fine chromatin, and nucleoli. CFU-E (colony-forming units) They form small colonies. They do not require BPA but require other factors like erythropoietin. CFU-E cells give rise blast cells. CFU-E cells are more mature than BFU-E cells. Morphologically, they are similar to BFU-E cells.
- 14. ERYTHROPOIESIS - PROERYTHROBLAST These cells develop from CFU-E. They are large cells, 15-20 µ in diameter. The nucleus is large containing basophilic nucleoli. It occupies 80% of the cells. Cytoplasm is scanty and basophilic. These cells actively divide by mitosis. They do not have hemoglobin.
- 15. ERYTHROPOIESIS - EARLY NORMOBLAST •10-16 µ in diameter. •They also show active mitosis. •The nucleus is large, the cytoplasm is basophilic, and hemoglobin •begins to appear. •The nucleoli disappear and condensation of chromatin begins in the stage.
- 16. ERYTHROPOIESIS - INTERMEDIATE NORMOBLAST • 10-14 µ in diameter. • The nucleus becomes small. • Mitosis stops at this stage. • Hemoglobin concentration increases and cells become acidophilic due to Hb. • The condensation of nuclear chromatin increase in this stage.
- 17. ERYTHROPOIESIS -LATE NORMOBLAST 8-10 µ in diameter. The cytoplasm is acidophilic. The nucleus is very small, becomes pyknotic (small), and is lost by extrusion.
- 18. ERYTHROPOIESIS - RETICULOCYTE • It is slightly basophilic. • Hb content increases to reach the level of the mature cell. • The chromatin is organized in the form of a network (reticulum); hence, it is called a reticulocyte. • RBC attains maturity in 1-2 days after the loss of the basophilic material.
- 19. ERYTHROPOIESIS - ERYTHROCYTES This is a mature cell, 7-2 µ in diameter, eosinophil, non-nucleated; it resembles a biconcave disk. The process of erythropoiesis takes 7 days.
- 20. FACTORS AFFECTING ERYTHROPOIESIS- Erythropoietin • Glycoprotein hormone that stimulates erythropoiesis. It increases RBC production. • It has a molecular weight of 46,000. It is made up of 74% protein and 26% carbohydrate. • Formation: It is mainly formed in the kidney and partly in the liver. In the kidney it is produced by the endothelial cells of the peritubular capillaries.
- 21. Erythropoietin - Functions • Increases RBC production. Enhances synthesis of Hb. Hastens maturation of RBC. • The basic stimulus for erythropoietin production is hypoxia. Androgens increase erythropoietin production. Estrogens depress erythropoietin production. Products of RBC destruction increase erythropoietin production. Vasoconstrictors produce renal hypoxia. They cause formation of erythropoietin. Erythropoietin is inactivated in the liver and is excreted through the kidneys.
- 22. Stimulus for Erythropoietin Androgens: Stimulate erythropoiesis. Therefore, men have a higher RBC count compared to women. Androgens stimulate the production of erythropoietin. In addition, they directly stimulate erythropoiesis. Estrogens: They have inhibitory effect on the erythropoiesis by suppression of erythropoietin production. Hormones: Thyroxin, cortisol, and growth hormone are necessary for RBC production. Interleukin 1,5, and 3, granulocyte macrophage colony- stimulating factor (GM-CSF), and BPA all act as local hormones and help in the conversion of stem cells to progenitor cells.
- 24. Stimulus for Erythropoietin Dietary Factors: Iron is necessary for Hb synthesis. The deficiency of iron leads to hypochromia and decrease in the size of RBC. Vitamin B12 and folic acid are necessary for maturation of RBC. Vitamin B6 vitamin C, copper, and cobalt act as cofactors.
- 26. Conditions decrease RBC count Physiological:
- 27. Conditions decrease RBC count Anemia This is a clinical condition wherein RBC count or Hb% or both are decreased. In anemia, O2 carrying capacity of blood is reduced. Pathological:
- 29. Conditions increase RBC count Physiological:
- 30. Conditions increase RBC count Pathological:
- 31. Conditions increase RBC count Pathological:
- 32. Conditions increase RBC count Pathological:
- 33. UNIVERSITY ASKED QUESTIONS • Define erythropoiesis. Describe the stages of erythropoiesis and identify the factors influencing it 10m [1+7+2] • Outline the steps of erythropoiesis. Explain the essential factors for it? [july-aug-2014].4m • Erythropoiesis 4m [July; 2012] • Erythropoietin 2m [july-2010]
- 34. Thank you