How do the blood cells being produce in bone marow, explain the processes and what chemical reaction is taking

Answer 1

Essentially all blood cells in the body, leukocytes and lymphocytes, are derived from multipotent hematopoietic stem cells (HSCs) that resides in the bone marrow. How HSCs become committed to a particular blood cell lineage is still being actively studied as there are many seperate mature blood cell types. This is not simply a chemical reaction that takes place but a multitude of extracellular signals that converge over time and at critical points in the differentiation of the HSC into whatever unipotent progenitor that gives rise to whichever mature blood cell lineage. These signals are instructive but do depend on the environment or niche the cell resides in and to some degree its developmental history. Sometimes a specific niche is required, like T-cell lymphopoiesis in the thymus. However, as a side note naive T-cells that survive differentiaton and selection in the thymus are still not functional as they exit the thymus as they have no met their cognate ligand. When HSCs differentiate in the bone marrow, a process that is still being defined but likely involves leaving what is called the endosteal niche, comprised of osteoblasts or bone forming cells in the marrow that directly contact the HSCs, the HSCs are found to move into the vascular niche or someother compenent of the bone marrow or other hematopoietic organ site (thymus, spleen, lymph node, etc.) as they go through various stages of lineage potential or restriction. They cannot go back to being an HSC, an erythrocyte cannot become a lymphocyte or macrophage as it is a terminally differentiated cell type that has committed to one cell type. If you are refering to erythropoiesis, mostly the erythropoietin receptor (EPO-R) and the interaction with its cognant ligand erythropoietin (EPO), a potent stimulator of erythropoiesis, is important in the making of red blood cells. When EPO binds to EPO-R, a cell surface receptor, information gets transmitted across the cell membrane and into the cell that causes a signal transduction cascade, another name for a directed aggregate of chemical reactions, that result in the cell that can become a red blood cell, the HSC or progenitor that has erythoid potential , to be instructed to become a red blood cell.