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Erythropoietin (/ ɪ ˌ r ɪ θ r oʊ ˈ p ɔɪ. ɪ t ɪ n,-r ə-,-p ɔɪ ˈ ɛ t ɪ n,-ˈ iː t ɪ n /; [1] [2] [3] EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production (erythropoiesis) in the bone marrow.
The osteoclast disassembles and digests the composite of hydrated protein and mineral at a molecular level by secreting acid and a collagenase, a process known as bone resorption. This process also helps regulate the level of blood calcium. Osteoclasts are found on those surfaces of bone that are undergoing resorption.
Bone resorption is resorption of bone tissue, that is, the process by which osteoclasts break down the tissue in bones [1] and release the minerals, resulting in a transfer of calcium from bone tissue to the blood. [2] The osteoclasts are multi-nucleated cells that contain numerous mitochondria and lysosomes. These are the cells responsible for ...
The organic part of bone is about 20% of the dry weight, and counts in, other than osteopontin, collagen type I, osteocalcin, osteonectin, and alkaline phosphatase. Collagen type I counts for 90% of the protein mass. The inorganic part of bone is the mineral hydroxyapatite, Ca 10 (PO 4) 6 (OH) 2.
The tibia and femur cease to be important sites of hematopoiesis by about age 25; the vertebrae, sternum, pelvis and ribs, and cranial bones continue to produce red blood cells throughout life. Up to the age of 20 years, RBCs are produced from red bone marrow of all the bones (long bones and all the flat bones).
Osteocalcin, also known as bone gamma-carboxyglutamic acid-containing protein (BGLAP), is a small (49-amino-acid [5]) noncollagenous protein hormone found in bone and dentin, first identified as a calcium-binding protein. [6] Because osteocalcin has gla domains, its synthesis is vitamin K2-dependent. In humans, osteocalcin is encoded by the ...
Thrombopoietin is a glycoprotein hormone produced by the liver and kidney which regulates the production of platelets. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that bud off large numbers of platelets. [5] Megakaryocytopoiesis is the cellular development process that leads to platelet production.
The skeleton, often referred to as the skeletal system, is important both as a supporting structure and for maintenance of calcium, phosphate, and acid-base status in the whole organism. [5] The functional part of bone, the bone matrix, is entirely extracellular. The bone matrix consists of protein and mineral. The protein forms the organic matrix.