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These processes produce growth and differentiation of cells and increase in body size, a process that involves synthesis of complex molecules. Examples of anabolic processes include the growth and mineralization of bone and increases in muscle mass.
The mechanism behind this is two-fold: cortisol stimulates the production of RANKL by osteoblasts which stimulates, through binding to RANK receptors, the activity of osteoclasts – cells responsible for calcium resorption from bone – and also inhibits the production of osteoprotegerin (OPG) which acts as a decoy receptor and captures some ...
Bone is resorbed by osteoclasts, and is deposited by osteoblasts in a process called ossification. [6] Osteocyte activity plays a key role in this process. Conditions that result in a decrease in bone mass can either be caused by an increase in resorption or by a decrease in ossification. During childhood, bone formation exceeds resorption.
Feedback from physical activity maintains bone mass, while feedback from osteocytes limits the size of the bone-forming unit. [ 33 ] [ 34 ] [ 35 ] An important additional mechanism is secretion by osteocytes, buried in the matrix, of sclerostin , a protein that inhibits a pathway that maintains osteoblast activity.
Most of the receptor activities that play an important role in bone function are present in the mature osteocyte. [6] Osteocytes are an important regulator of bone mass. [15] [16] Osteocytes contain glutamate transporters that produce nerve growth factors after bone fracture, evidence of a sensing and information transfer system. [6]
Serotonin can also be synthesized, albeit at very low levels, in the bone cells. It mediates its actions on bone cells using three different receptors. Through 5-HT 1B receptors, it negatively regulates bone mass, while it does so positively through 5-HT 2B receptors and 5-HT 2C receptors. There is very delicate balance between physiological ...
The utilization of bone to buffer even a small percentage of daily acid production can lead to significant loss of bone mass in the course of a decade. [10] Additionally, as the body ages there is a steady decline in renal function.
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).