The Physiology Of The Red Blood Cells pdf
- 1. The Physiology Of The Red Blood Cells BY – JYOTI MAURYA ( M. PHARM PHARMACEUTICS )
- 2. Introduction 1. Blood is a mesodermal derived special connective tissue . 2. Components of Blood. 3. RBC are vital component of circulatory system they are specialized ,a nucleated, biconcave cells, designed for efficient gaseous exchange.
- 3. Structure of RBC 1. Shape - biconcave disc which increases surface area to volume ratio for rapid gas exchange and flexibility to pass through the narrow capillaries. 2. Size - 7-8 um diameter & 2 um thickness 3. Number - Male 5.4 million/ul Female 4.8 million /ul 4. No nucleus and cell organelles , on maturation membrane bound organelles degenerate like Nucleus , Mitochondria , Ribosome . 5. RBC contains a meshwork of structural protein "Stomatin" in which Hb molecules remain packed .
- 4. Site of Erythropoiesis Stage / Age Time Period Main Site of Erythropoiesis Notes Megaloblastic Stage Up to 3 months of gestation Yolk sac (mesoderm) First stage of development Hepatic Stage 3 months – birth Liver, Spleen Major site during this period Myeloid Stage 5th month onwards (intrauterine) Bone marrow Becomes main site after 3rd trimester Children Postnatal (till adolescence) All bones with Red Bone Marrow Active in both long and flat bones Adults (15–20 yrs onwards) After adolescence Flat bones: skull, sternum, ribs, pelvis Ends of long bones: femur, humerus Limited to specific bones
- 6. Erythropoiesis 1. After birth bone marrow becomes the sole site of erythropoiesis, 2. In young children, active hematopoietic bone marrow is found in both axial skeleton and bones of extremities, 3. The active hematopoietic bone marrow is red in color due to marked cellularity - Red bone marrow. 4. However, there occurs a progressive fatty placement throughout the long bones converting red bone marrow to the yellow bone marrow. 5. After 20-30 years, erythropoiesis is mostly limited to sternum, ribs, vertebrae, skull, pelvic and pectoral girdles.
- 7. Stages of Erythropoiesis STEM CELLS • Pluripotent stem cells are the mother stem cells that form stem cells for different cell lines. • It possess two fundamental properties : o Self-replication - they are capable of giving rise to more stem cells o Differentiation - they have the ability to differentiate into specialized cells called progenitor cells.
- 9. Stages of Erythropoiesis Stage Cell Size & Shape Morphological Features 1. Pluripotent Cell 20–25 µm, round, large Nucleus large, cytoplasm basophilic 2. Proerythroblast 15–20 µm, irregular, rounded or oval Multiple nucleoli, cytoplasm less, strongly basophilic (polyribosomes), high RNA, Hb absent 3. Early Normoblast 14–16 µm, irregular round or slightly oval Large nucleus, thick chromatin strands, cytoplasm basophilic, Hb absent 4. Intermediate Normoblast 10–14 µm Nucleus smaller, chromatin condensed, cytoplasm polychromatophilic (RNA + Hb) 5. Late Normoblast 8–10 µm, round Nucleus very small (pyknotic) 6. Reticulocyte 7–8 µm, biconcave, irregular Immediate precursor of RBC, nucleus absent, Hb increased, immature RBC released into blood, matures in 1–2 days 7. Erythrocyte 7.2–7.5 µm, biconcave disc No nucleus, no organelles, fully mature, carries Hb and O₂
- 10. Regulation of erythropoiesis • General factors o Hypoxia -> erythropoietin o Growth inducers o Vitamins • Maturation factors o Vitamin B 12 o Folic acid • Factors necessary for hemoglobin production o Vitamin C -> Helps in iron absorption (Fe+++ -> Fe++) o Proteins > Amino Acids for globin synthesis o Iron & copper > Heme synthesis o calcium, bile salts, cobalt & nickel.
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