Hemogenesis
In the adult shaped elements – erythrocytes, granulocytes, or granular leukocytes, and platelets – are formed mainly in the bone marrow of flat bones: sternum, ribs, spine and in the ends (epiphysis) bones. Lymphocytes develop in the lymph nodes and spleen, and also in the thymus, monocytes – in the bone marrow and reticular cells.
All blood cells develop from undifferentiated mesenchymal cells from embryonic or adult fixed reticular cells. This cell gives rise to all blood corpuscles is gemogistoblast turning into hematocytoblast containing core. The formation of red blood cells stimulate erythropoietin, which are synthesized in the kidneys with significant blood loss, oxygen starvation, and other conditions that reduce the amount of red blood cells and impairs their function. Erythropoietin humoral directly affect the bone marrow. They are resistant to high temperatures and is thought to relate to compounds of carbohydrates to proteins – glycoproteins. Since they are detected in the plasma of healthy people, they can be regarded as erythropoietic agents under physiological conditions.
When a rapid loss of a large number of white blood cells in the blood to leykopoetiny acting on the bone marrow is similar to erythropoietin and causes the formation of granulocytes. When thrombocytopenia come thrombopoietin.
Vitamins involved in hematopoiesis.
Vitamin B12 and folic acid are necessary for erythropoiesis. Vitamin B12 is supplied with food in an animal protein. In the stomach, the connection with vitamin B12 in animal protein is broken and it is connected with the “intrinsic factor” Kastla (1929), which is secreted by additional cells of the gastric glands of the fundus and remove the vitamin from food. This factor – gastric mukoproteidov – Connect peptides with polysaccharides. “Intrinsic factor” ensures the absorption of vitamin B12 in the blood in the small intestine, mainly in the lower part of the ileum, and the absorbed. The protein portion of mukoproteidov affect the absorption of vitamin and mucous – protects vitamin from destruction. The capillaries intestinal vitamin B12 connected globulin, and is not associated with deleted globulin in the urine.
In a healthy person the content of vitamin B12 in the blood is equal 100-900 g / dm3. With age, pregnant and feeding plant foods the amount of vitamin in the blood decreases. It accumulates in the mitochondria of the liver, kidney and heart, which is supplied from the bone marrow. In the liver, it is delayed until 3 months. Folic acid coming from the plant food is well absorbed into the blood in the lower small intestine. It is synthesized intestinal microorganisms. Pregnant its content in blood decreases. In the presence of vitamin B12 and C, it is converted in the liver to active folinic acid.
Both vitamins (B12 and folic acid) are actively involved in the synthesis of globin and education in erythroblasts nucleoproteins and nucleic acids. Folic acid and vitamin C are involved in the synthesis of the purine compounds of these acids, and vitamin B12 – pyrimidine. With a lack of vitamin B12 and folic acid formation of hemoglobin is broken. Vitamin C enhances iron absorption in the intestine 8-10 times and thereby promotes erythropoiesis. Usually about 10% of absorbed iron food accumulates in the liver and spleen, where its content is equal to 500-1000 mg. The loss of iron by the body of mammals insignificant. The synthesis of heme and globin also provides vitamin B6.
Erythropoiesis excited decay products erifotsitov old. By age hematopoiesis is greatly reduced due to the degeneration of the bone marrow and lymphoid tissue.
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