The extracellular matrix (ECM) of bone is considered to be a composite material made up of organic and inorganic matter. What makes up the organic and inorganic portions of the matrix? Describe the cellular mechanism involved in breaking down this matrix; include the bone cell required for the process.
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Explanation : It is comprised of organic and inorganic substances. The organic component of the bone matrix includes the collagen and ground substance whereas the inorganic component is the inorganic bone salts, mainly the hydroxyapatite. The collagen and ground substance form approximately 25% of the bone mass. Collagen fibers, glycosaminoglycans, and glycoproteins are organic while
hydroxyapatite (crystallized calcium and phosphate) makes up most of the inorganic portion.
Acid phosphates secreted by the osteoclast target the collagen fibers for destruction.
The osteoclast has hydrogen pumps present in high numbers on the ruffled border.
Mechanism: As hydrogen ions are pumped out they combine with chloride ions forming hydrochloric acid (HCl). The acid acts directly on hydroxyapatite to liberate calcium. Additionally HCL increases the solubility of calcium so it can be transferred back into the blood for
other uses .