The easy description of how the immature RBC's convert into the matured ones.

1. ERYTHROPOESIS
Dr. Srishti Agarwal

2. Definition
• The process of formation (origin, development and maturation) of RBCs is called
Erythropoiesis.
• Difference between erythropoiesis and Haemopoesis (formation of all the blood
cells)

3. Sites
• In the fetal life-
- 1st two months of IUL (Mesoblastic stage) – RBS are produced inYolk sac
- From 3rd month (Hepatic stage)- From the liver and organs like spleen is also involved
• Last 3 months of IUL (Myeloid stage)- Red bone marrow
• New born babies till 20 years- Red bone marrow of all long and flat bones
• After 20 years- From membranous bones like ribs, sternum, vertebra, skull bones

4. Stages
• It occurs in 6 stages-
1) Proerythroblast
2) Early normoblast
3) Intermediate normoblast
4) Late normoblast
5) Reticulocyte
6) Matured erythrocyte

6. Proerythroblast
• Also called mega oblast because of it’s large size
• This cell is round in shape and size is around 15-20 micrometer in size
• It has a central nucleus. 2-3 nucleoli and endoplasmic reticulum network
• No hemoglobin is present at this stage
• Cytoplasm is deep basophilic
• Multiplies several times to form early normoblast

7. Early normoblast
• Also called basophilic erythroblast
• It is little smaller in size in comparison to proerythroblast
• Diameter is around 12-18 micrometer
• Reticular network thick and dense
• It is also round in shape and shows mitosis
• Nucleoli disappears and cytoplasm is still basophilic

8. Intermediate normoblast
• 10-15 micrometers and round in shape, smaller than early cell
• Also called Polychromatophil erythroblast
• Even more condense reticule network
• Presence of hemoglobin and coarse chromatin network
• Nucleus is present but the nuclei is absent
• Cytoplasm is here shows both acidic and basic properties

9. Late normoblast
• Also called orthochromatic erythroblast.
• Diameter is 7-12 micrometers and round in shape
• Hemoglobin increases and cytoplasm becomes acidic.
• The nucleus is small and nuclear lysis is seen in this stage.
• Chromatin network shows full condensation at this stage.

10. Reticulocyte
• Also called immature RBC.
• Cytoplasm contains so much reticuli network
• It has few mitochondria
• Presence of large amount of hemoglobin

11. Matured erythrocyte
• Reticule network also disappears
• Cell start appearing biconcave
• Size is 7.2 micrometer
• Large amount of hemoglobin without nucleus

12. • This cycle takes around 7 days.
• The 1st 5 stages that is conversion from proerythroblast to reticulocyte takes about
5 days.
• It takes about 2 days from reticulocyte to convert in to matured erythrocyte

13. Functions of Blood in transport of
nutrients

14. • The blood carries nutrients such as vitamins, minerals, sugars, fats and
proteins around the body.
• Digested nutrients are absorbed into the blood through capillaries in the small
intestine.They are then moved to the cells around the body where they are
needed.
• The blood vessels near to the cells are small in diameter so the blood
flows more slowly, allowing the cells to take up nutrients from the blood
and to exchange waste products into the blood to be removed.
• Waste products are transported to the organs that remove them from the blood and
then eliminate them from the body. For example, excess water is filtered out by the
kidneys and toxins are removed from the blood by the liver.

16. Lymphatic system
• The lymphatic system, or lymphoid system, is an organ system in vertebrates
that is part of the immune system, and complementary to the circulatory system.
It consists of a large network of lymphatic vessels, lymph nodes, lymphoid
organs and lymph.

18. Functions
• The human circulatory system processes an average of 20 litres of blood per day
through capillary filtration, which removes plasma from the blood. Roughly 17
litres of the filtered blood is reabsorbed directly into the blood vessels, while the
remaining three litres are left in the interstitial fluid. One of the main functions of
the lymphatic system is to provide an accessory return route to the blood for the
surplus three litres.
• The other main function is that of immune defense. Lymph is very similar to blood
plasma, in that it contains waste products and cellular debris, together
with bacteria and proteins.The cells of the lymph are mostly lymphocytes.
Associated lymphoid organs are composed of lymphoid tissue, and are the sites
either of lymphocyte production or of lymphocyte activation.These include
the lymph nodes (where the highest lymphocyte concentration is found),
the spleen, the thymus, and the tonsils. Lymphocytes are initially generated in
the bone marrow.

19. • Lymph vessels called lacteals are at the beginning of the gastrointestinal tract,
predominantly in the small intestine.While most other nutrients absorbed by
the small intestine are passed on to the portal venous system to drain via
the portal vein into the liver for processing, fats (lipids) are passed on to the
lymphatic system to be transported to the blood circulation via the thoracic duct.

20. Structure
• PRIMARY LYMPHOID ORGANS
• Bone marrow- Bone marrow is responsible for both the creation ofT
cell precursors and the production and maturation of B cells, which are important
cell types of the immune system. From the bone marrow, B cells immediately join
the circulatory system and travel to secondary lymphoid organs in search of
pathogens.T cells, on the other hand, travel from the bone marrow to the thymus,
where they develop further and mature.
• Thymus-The thymus increases in size from birth in response to postnatal antigen
stimulation.The thymus is located between the inferior neck and the superior
thorax.The thymus is where theT lymphocytes mature and become
immunocompetent.The loss or lack of the thymus results in severe
immunodeficiency and subsequent high susceptibility to infection.

21. • SECONDARY LYMPHOID ORGANS
• Spleen- It produces white blood cells and filters blood to eliminate pathogens,
damaged red blood cells, and platelets.
• Lymph nodes- A lymph node is an organized collection of lymphoid tissue,
through which the lymph passes on its way back to the blood. Lymph nodes are
located at intervals along the lymphatic system.
• LYMPHVESSELS-The lymphatic vessels, also called lymph vessels, are thin-walled
vessels that conduct lymph between different parts of the body.They include the
tubular vessels of the lymph capillaries, and the larger collecting vessels–the right
lymphatic duct and the thoracic duct (the left lymphatic duct).The lymph
capillaries are mainly responsible for the absorption of interstitial fluid from the
tissues, while lymph vessels propel the absorbed fluid forward into the larger
collecting ducts, where it ultimately returns to the bloodstream