Bone resorption is a process whereby bone matrix is ____________ by substances released by ____________ . The lysosomes inside o
f these cells release ____________ that digest the organic components of the matrix. The mineral part of the matrix is dissolved by ____________ . The calcium and phosphate ions enter the ____________ . Bone resorption may occur when blood calcium levels are ____________ .
Resorption is the loss of substance from any mineralized tissue, mediated by cellular and humoral systems of their own. The four mineralized tissues of our economy, bone, cement, dentin (mineralized fraction of the dentino-pulp functional complex) and enamel, offer different degrees of resistance to resorption. The bone has the greatest lability and the enamel the least. The fact that the bone tissue is the least resistant to resorption is used to move and reposition teeth by controlled forces (orthodontics); and the fact that the enamel is the most resistant has led to think that it does not suffer from resorption.
Osteoclasts They are the spring cells par excellence; they belong to the lineage of the monocitomacrophages. They are large, multinucleated mobile cells, with a clear area and a rough brush border that live for about two weeks and disappear by apoptosis (cell death programmed by fragmentation in membrane particles that allows their phagocytosis without inflammation). They are responsible for the destruction of the organic and inorganic parts of the mineralized bone fraction. They are active both in the processes of the physiological renewal of the bone and in those of its pathological loss.
The population of all the mitochondria of a given cell constitutes the chondriome. A single mitochondrion is often found in unicellular organisms, while human liver cells have about 1000–2000 mitochondria per cell, making up 1/5 of the cell volume.
