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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 plasma total calcium concentration is in the range of 2.2–2.6 mmol/L (9–10.5 mg/dL), and the normal ionized calcium is 1.3–1.5 mmol/L (4.5–5.6 mg/dL). [4] The amount of total calcium in the blood varies with the level of plasma albumin, the most abundant protein in plasma, and therefore the main carrier of protein-bound calcium in the blood.
The sealing zone is the attachment of the osteoclast's plasma membrane to the underlying bone. Sealing zones are bounded by belts of specialized adhesion structures called podosomes . Attachment to the bone matrix is facilitated by integrin receptors, such as αvβ3, via the specific amino acid motif Arg-Gly-Asp in bone matrix proteins, such as ...
These collagenases break down protein into peptides. The peptides are subsequently reduced to their constituent amino acids, which can be leached away by groundwater. Once the collagen has been removed from bone, the hydroxyapatite content is degraded by inorganic mineral weathering, meaning that important ions , such as calcium , are lost to ...
When plasma calcium levels fall, cell surface receptors are activated and the secretion of parathyroid hormone occurs; it then proceeds to stimulate the entry of calcium into the plasma pool by taking it from targeted kidney, gut, and bone cells, with the bone-forming action of parathyroid hormone being antagonized by calcitonin, whose ...
The plasma ionized calcium homeostat can be disrupted by the constant, unchanging, over-production of parathyroid hormone by a parathyroid adenoma resulting in the typically features of hyperparathyroidism, namely high plasma ionized Ca 2+ levels and the resorption of bone, which can lead to spontaneous fractures.
The SR contains ion channel pumps, within its membrane that are responsible for pumping Ca 2+ into the SR. As the calcium ion concentration within the SR is higher than in the rest of the cell, the calcium ions will not freely flow into the SR, and therefore pumps are required, that use energy, which they gain from a molecule called adenosine triphosphate (ATP).
Bone tissue is removed by osteoclasts, and then new bone tissue is formed by osteoblasts. Both processes utilize cytokine (TGF-β, IGF) signalling.In osteology, bone remodeling or bone metabolism is a lifelong process where mature bone tissue is removed from the skeleton (a process called bone resorption) and new bone tissue is formed (a process called ossification or new bone formation).