RED BLOOD CORPOSULES(RBC)

INTRODUCTION-ERYTHROCYTES
STRUCTURE
NORMAL COUNT
COMPOSITION
ERYTHROPOIESIS- PROCESS
HEMOGLOBIN
FUNCTIONS

1. R ED B LooD C ELLS BY   FASEEHA. R 18pw28158 I pg . Nutrition and dietetics

2. erythrocytes/ rbc Erythrocytes derived from greek word. " Erythros " - RED , " kytos " - hollow vessel, " cyte " - cell JAN SWAMMERDAM(DUTCH BIOLOGIST AND MICROSCOPIST) 1658 , NAMED IT AS " RUDDY GLOBULES " RBC CONTAIN HEMOGLOBIN – GIVES RED COLOR     TO THE BLOOD LACKS CELL ORGANELLS LIKE RIBOSOMES,    NUCLEOLUS, mitochondria

3. STRUCTURE SHAPE-   CIRCULAR BICONCAVE DISCS IN ALL MAMMALS(EXCEPT CAMELS AND IILAMAS –OVAL SHAPE)  SPECTRIN - MAINTAINS SHAPE AND FLEXIBILITY SIZE-   7 MICRONS IN DIAMETER THICKNESS- 2 MICRONS AT PERIPHERY    AND 1 MICRONS AT CENTRE MAMMALIAN RBC- NON NUCLEATED    ( OTHER VERTEBRATES CONTAIN NUCLEUS)

4. NORMAL COUNT Erythrocyte count        No. Of rbc per cubic millimetre of blood                Male - 4.5-6.5 million/cubic millimetre           Female - 4.5-5 million / cubic millimetre          At birth – 6.7 million/ cubic millimetre  

5. Packed cell volume         Volume of rbc per cubic millimetre of blood                  40-50/cubic millimetre Hemoglobin       Weight of hemoglobin in whole      blood meASURED IN GRAMS/100ML               MALE :   13-18 GRAMS/100ML          FEMALE :   11.5-16.5 GRAMS/100ML

6. COMPOSITION

7. ERYTHROPOIESIS PROCESS OF PRODUCTION OF RBC INVOLVES- ORIGIN, DEVELOPMENT AND MATURATION OF RBC IN THE BODY SITE OF ERYTHROPOIESIS         1) 0-2 MONTHS OF INTRAUTERINE LIFE- MESENCHYMAL CELLS                                                                                     OF YOLK SAC         2) 3-6 MONTHS-  LIVER         3) 7- 9 MONTHS AND AFTER BIRTH- BONE MARROW

8. RED BONE MARROW - SITE OF ERYTHROPOEISIS IN NEW BORN, CHILDHOOD AND ADULTHOOD AT AGE OF 20- SHAFTS OF LONG BONES BECOME YELLOW DUE TO FAT DEPOSIT AND BECOME UNABLE TO PRODUCE RBC THUS FLAT BONES - STERNUM,RIBS,VERTEBRATE, SKULL BONES   PROXIMAL END OF LONG BONES PRODUCE RBC

9. PROCESS OF ERYTHROPOIESIS

10. COMMITED STEM CELLS THAT PRODUCE ERYTHROCYTES ARE CALLED COLONY FORMING UNIT ERYTHROCYTE(CFU-E) PHSC ARE UNCOMMITED STEM CELLS WHREAS CFU-E ARE CELLS COMMOTED TO PRODUCE RBC CFU-E CELLS DIVIDE INTO PROERYTHROBLAST . PROERYTHROBLAST DIVIDE MULTIPLE TIMES AND GIVE RISE TO MATURE RBC

11. 1. PROERYTHROBLAST THESE DEVELOP FROM CFU-E LARGE CELL, HAVE DIAMETER OF ABOUT        20 MICRONS        HAS NUCLEUS WITH 1/MORE NUCLEOLI DOES NOT CONTAIN HEMOGLOBIN MULTIPLIES NUMEROUS TIMES TO PRODUCE BASOPHILIC ERYTHROBLASTS

12. 2. BASOPHILIC ERYTHROBLASTS DIAMETER – 15 MICRONS HAS NUCLEUS BUT NUCLEOLUS DISAPPEARS CHROMATIN NETWORK CONDENSES HEMOGLOBIN ABSENT CYTOPLASM IS BASOPHYLIC IN NATURE    ( STAINS BASIC DYES))

13. 3. polychromatophil erythroblast Diameter 10-12 microns Nucleus still present Chromatin network condenses more Accumulates hemoglobin Cytoplasm- basophylic .due to hb it stains both acidic and basic dyes hens called polychromatophil .

14. 4. orthochromatic erythroblast Diameter 8-10 microns Beginning of this stage nucleus becomes    extremely small - 'ink nucleus' At the end of stage nucleus disappears Accumulates greater hb so cytoplasm becomes more acidophilic hence orthochromatic

15. 5.reticulocytes Called immature rbc Slightly large than immature rbc Stains with basic dyes due to presence of golgi apparatus, mitochondria and other cellular organelles

16. 6.mature erythrocytes/ rbc Diameter 7 microns Attains biconcave shape Lacks nucleus and other oganelles It takes 7 days for the development of rbc from proerythrocytes Takes 5 days upto the stage of reticulocytes and 2 more days to form rbc

17. Factors 1) erythropoietin( circulating hormone) Principle stimulus for rbc production in low oxygen status 90% of it is formed in kidney by renal tubular epithelial cells, remaining formed in liver Stimulate the production of proerythroblast form hematopoietic stem cells of bone marrow.

18. 2. vitamin b12 and folic acid Necessary for the final maturation of rbc Present in normal diet containing dairy products, meat, green leafy vegetables. Destruction of erythrocytes Life span of rbc is 120 days No. Of rbc remain fairly constant , that is the bone marrow produces rbc at the rate at which they are destroyed- homeostatic negative feedback mechanism

19. hemoglobin Complex protein, mw-68,000 Protein part – globin made up of  4 polypeptide chains (2 alpha and 2 beta) Heme part is porphyrin made up of 4 pyrole ring Synthesized inside developing erythrocytes of red bone marrow Hb in mature rbc combines with oxygen – oxyhemoglobin giving arterial blood red color In this way bulk of oxygen absorbed from lungs transported around the body Each hb contains 4 atoms of iron. Each atom can carry 1 molecule of oxygen therefore one hb molecule carries up to 4 molecules of oxygen

20. functions 1. primary function-carry oxygen from lungs to tissue around the body. 2.secondary function- ability of rbc to carry co2 from tissues to lungs, where it can be breathed out. 3.rbc contain enzyme carbonic anhydrase. As co2 enters rbc , this enzyme with the help of water converts it to bicarbonate which is used to control ph and excreted via lungs.

21. Reference  1) anatomy and physiology in health and illness     by ross and wilson   2)essentials of medical physiology by  k.sembulingam  3)physiologyplus.com  4) www.slideshare.com