Erythropoiesis:
Erythropoiesis refers specifically to the formation of erythrocytes the bone marrow or myeloid tissue is the primary site of erythropoiesis in the adult red bone marrow of the vertebrae sternum ribs skull scapulae pelvis and proximal limb bones is actively involved in hemopoesis during the process of erythropoiesis adequate supplies of amino acids iron and vitamin b12 are required erythrocytes are formed from the stem cells (hemocytoblast) which reside in the red bone marrow maturation pathway from hemocytoblast to erythrocytes occurs in three phases the pathway is regulated mainly by a glycoprotein hormone formed in the kidney and named as erythropoietin (erythropoiesis stimulating hormone ) when the kidney cells are deprived of oxygen they step up the release of erythropoietin thus gross RBC destruction haemorrhage high altitudes pneumonia aerobic exercise cause reduction in oxygen supply to kidney cells and thus erythropoetin production occurs
phase of erythropoiesis:
Erythroieposis as earlier occurs in three distinct phases:
(1) Increased production of ribosomes in the maturing erythrocytes
(2) synthesis of haemoglobin at these ribosomes
(3) Ejection of the erythrocyte nucleus and most of its organelles
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