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INTRO TO HEMATOPOIETIC SYSTEM . HEMATOPOIETIC SYSTEM INumber of blood cells in the blood stream depends on three factors: -- Rate of production -- Rate of release -- Length of survival There are two types of marrow: -- Yellow marrow (Inactive) composed primarily of fat. -- Red marrow (active in
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1. Hematopoietic and lymphoid systems ??.????? ??????????
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2. INTRO TO HEMATOPOIETIC SYSTEM HEMATOPOIETIC SYSTEM I
Number of blood cells in the blood stream depends on three factors:
-- Rate of production -- Rate of release
-- Length of survival
There are two types of marrow:
-- Yellow marrow (Inactive) composed primarily of fat. -- Red marrow (active in hematopoiesis)
3. Hematopoietic system Distribution of active marrow can be determined by administering radioactive iron:
LOCATION % of TOTAL MARROW
Pelvis 40
Vertebrae 28
Cranium-mandible 13
Ribs 8
Sternum 2
Ends of long bones 8
Total marrow space in the adult is about 4 liters. About half of this is active. Total marrow space in the child is about 1.6 liters. It is nearly 100% active though.
Remember - The spleen and lymph nodes are also part of this system.
4. Hemopoiesis The Pluripotential (Totipotential) Stem Cell
The pluripotential stem cell is defined as the precursor cell from which all erythrocytes, leukocytes, and megakaryocytes are derived (i.e. all blood cells have a common cell line of origin).
5. Hemopoiesis
6. Erythropoiesis * maturation time in the bone marrow can be decreased to 2-3 days in response to an acute stress like an acute blood loss or hemolysis. The bone marrow has three mechanisms at its disposal to respond to an acute decrease in circulating erythrocytes: The marrow can increase the number of cells in the erythroid pool by increasing the number of stem cells that will differentiate into erythrocytes; The marrow can decrease the time it takes for each erythroid cell to reach maturation; or The marrow can release reticulocytes into the bloodstream earlier.