In the human body, an osteoblast is a type of cell involved in the formation of which tissue?
Osteoblasts are cells with a single nucleus that synthesize bone. However, in the process of bone formation, osteoblasts function in groups of connected cells. Individual cells cannot make bone. A group of organized osteoblasts together with the bone made by a unit of cells is usually called the osteon.
The skeleton is a large organ that is formed and degraded throughout life in the air-breathing vertebrates. 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. 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'. It is synthesized and then the mineral is added. The vast majority of the organic matrix is collagen, which provides tensile strength. The matrix is mineralized by deposition of hydroxyapatite (naturally occurring mineral form of calcium apatite). This mineral is hard, and provides compressive strength. Thus, the collagen and mineral together are a composite material with excellent tensile and compressive strength, which can bend under a strain and recover its shape without damage. This is called elastic deformation. Forces that exceed the capacity of bone to behave elastically may cause failure, typically bone fractures.