Medicina Fluminensis, Vol. 51 No. 4, 2015.
Pregledni rad
The remodeling of the skeleton
Sanja Zoričić Cvek
; Zavod za anatomiju, Medicinski fakultet Sveučilišta u Rijeci
Dragica Bobinac
; Zavod za anatomiju, Medicinski fakultet Sveučilišta u Rijeci, Rijeka
Luka Đudarić
; Zavod za anatomiju, Medicinski fakultet Sveučilišta u Rijeci, Rijeka
Olga Cvijanović
; Zavod za anatomiju, Medicinski fakultet Sveučilišta u Rijeci, Rijeka
Sažetak
The bones of the vertebrate skeleton serve two main functions: the first is biomechanical function which includes support and protection of internal organs and structures, so as providing a muscle attachment for the locomotion and the second is essential metabolic function which includes mineral homeostasis maintaining. In spite skeleton is being presented as “dead”, inert structure, as often medical students learn in anatomy, it is metabolically, extremely active organ and undergoes continuous lifelong changes. Bones are initially formed by modeling processes, which include the production and deposition of bone tissue at developmental and biomechanical sites of the skeleton. Before being fully formed, bones undergo remodeling process which continues throughout life, in order to preserve the structural integrity and biomechanical function, to adjust bone architecture according to mechanical demands, to repair microdamages, and if it is needed, to mobilize stored calcium and phosphorus. The remodeling process involves a series of highly regulated and tightly coupled cellular and molecular processes, performed by coordinated activity of osteocytes, osteoblasts and osteoclasts. These different bone cells are organized into specific morphological and functional bone multicellular units which perform and coordinate two basic bone biology processes: bone resorption and bone formation, throughout a cycle of events called bone remodeling. The bone remodeling cycle starts with phase of activation, which includes mechanosensation and mechanotransduction of the osteocytes, or with cellular response to systemic humoral factors such as PTH. These are start signals which induce a formation of a specific canopy structure over the bone surfaces which need to be remodeled, called the remodeling compartment. Furthermore, these signals will activate osteoclastic precursor to proliferate, differentiate, attach and to resorb bone surface in the following resorption phase. After the certain quantity of bone was removed, the reversal phase occurres, which involves releasing of numerous, yet unknown factors that couple bone resorption and upcoming bone formation and mineralization, which are done by osteoblasts in the formation phase. After the same quantity of new bone was formed, the termination phase proceeds in which the cycle ends and bone surfaces become quiescent or “at rest”.
Ključne riječi
bone; bone remodeling; osteoblasts; osteoclasts; osteoc
Hrčak ID:
148287
URI
Datum izdavanja:
1.12.2015.
Posjeta: 6.483 *