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Lecture 1 Hematopoiesis, Abdulkarim Aldosari. Objectives  Define hematopoiesis  Describe the origin of hematopoieisis  Define erythropoiesis  List.

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Presentation on theme: "Lecture 1 Hematopoiesis, Abdulkarim Aldosari. Objectives  Define hematopoiesis  Describe the origin of hematopoieisis  Define erythropoiesis  List."— Presentation transcript:

1 Lecture 1 Hematopoiesis, Abdulkarim Aldosari

2 Objectives  Define hematopoiesis  Describe the origin of hematopoieisis  Define erythropoiesis  List proper cell maturation of the erythrocytic series  Identify three areas of RBC metabolism crucial for normal erythrocyte survival and function  Describe RBC membrane biochemical structure and the consequences of structural membrane defects  Describe Hemoglobin structure, function and synthesis  RBC metabolic pathways

3 Hematopoiesis  Blood cell formation – production and development  Occurs bone marrow, liver, spleen, lymph nodes, thymus  Bone marrow – sole site of effective hematopoiesis in normal adults  6 billion cells/kg of body weight per day  2.5 billion red cells  2.5 billion platelets  1.0 billion white cells  Rate adjusted to need, vary from nearly zero to many times the normal  Constant turnover of cells

4 Origin of Hematopoiesis  Yolk sac > fetal liver/spleen > BM  Primitive erythroblast > migrate to liver (6wks) – includes other myeloid and lymphoid cells.  At birth the bone cavities are the only site of hematopoietic activity - Starts at 7 months Fig 1-16, pg. 10

5 Origin of Hematopoiesis

6  Shaft of long bones – until 4 yrs.  Sternum, ribs, pelvis, vertebrae, skull – at yrs.  Other bones have mostly yellow marrow (fat)  At 40 yrs – equal amount of yellow and red marrow

7 Origin of Hematopoiesis  Takes place in the entire medullary space during infancy and early childhood  Later – occurs in the extravascular part of red marrow  Squeeze through the endothelial lining cells that separates the extravascular marrow from the intravascular compartment- venous sinus  Migrating cells enter the peripheral blood

8 Hematopoiesis  Steady state of hematopoiesis i.e. production = removal  During increased demand for blood cells  strenuous exercise, high altitudes, smokers  To compensate - Spleen, liver and other tissues can start active hematopoiesis = Extramedullary hematopoiesis  Two pools of cells participate in hematopoietic activity:  Stem cell pool  Bone marrow pool

9 Hematopoiesis Hematopoietic stem cell pool  Pluripotential - multipotential stem cells (MSCs)  morphologically identical  Continuous self-renewal  Unipotential - committed progenitor cells  Restricted to single cell line  No self-renewal  Lymphoid or myeloid Fig 1-15, pg. 9

10 Figure 1-15

11 Hematopoiesis Bone marrow pool  proliferating and maturing cells - through the action of cytokines (growth factors) – CSF and IL progenitor cells divide and differentiate  Stored cells for later release to peripheral blood  Cells released to peripheral blood  Storage – WBCS, platelets  Functional – WBCs, platelets, RBCs  Fig 1-17, pg. 10

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