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Functional Anatomy
Published in James Crossley, Functional Exercise and Rehabilitation, 2021
Maintaining the health and integrity of bones is extremely important. Bone is continually being broken down, reabsorbed, deposited and remodeled. Osteocytes lay down minerals to maintain the strength and integrity of compact bone. Even as adults, bone is continually healing, repairing, growing and adapting along lines of stress and patterns of use.
Biochemistry of Exercise Training: Effects on Bone
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Panagiota Klentrou, Rozalia Kouvelioti
Osteoblasts partly originate from the stroma located in the bone marrow adjacent to the endosteum or in the periosteum. Bone is produced as layers (lamellae) of calcified material surrounding blood vessels. Throughout matrix formation, some osteoblasts are left behind and become embedded in the new matrix within cavities called lacunae. These trapped osteoblasts convert into mature bone cells called osteocytes and are nourished by long, slender, cytoplasmic processes that extend from the cells to the blood vessels in canals called canaliculi. These cells can then receive and transmit mechanical signals to other bone cells (neighbouring osteocytes, surface osteoblasts, or lining cells). Osteocytes account for more than 90% of adult bone cells, live the longest (up to 25 years), and as mechanosensitive cells, play an important role in the maintenance of bone mass and structure (28, 127). Both osteoblasts and osteocytes play an active role in mineral homeostasis by helping to release calcium from bone into the blood, which regulates the concentration of calcium in body fluids. The osteocyte lifespan depends on the rate of bone turnover (90).
Pathogenesis: Molecular mechanisms of osteoporosis
Published in Peter V. Giannoudis, Thomas A. Einhorn, Surgical and Medical Treatment of Osteoporosis, 2020
Anastasia E. Markatseli, Theodora E. Markatseli, Alexandros A. Drosos
At any given time, about 20% of the cortical bone and 80% of the cancellous bone undergo bone remodeling. Bone remodeling occurs in discrete units in the skeleton. These are called bone remodeling units (BRUs) (23,24). There are at least one million such tiny remodeling units at any given time in the adult skeleton (43). The transformation of an inactive bone surface to a surface capable of absorbing bone marks the onset of the bone remodeling cycle (23,24). It is believed that osteocytes communicate with osteoblasts and osteoclasts located on the bone surface by transferring to them local signals through a tubular system. Therefore, osteocytes mediate the onset of bone remodeling (44–47).
Discovery of potential biomarkers for osteoporosis diagnosis by individual omics and multi-omics technologies
Published in Expert Review of Molecular Diagnostics, 2023
Current detection methods cannot distinguish the periosteum, cortical bone, and cancellous bone, and the role of osteoblasts in the process of bone turnover is unclear. Studies have shown that the correlation between different cell subsets and gut microbiota can be revealed using single-cell technology [117]. Compared with bulk-cell omics, which mixes a group of cells together for research, it is difficult to recognize the heterogeneity between cells [135,136]. Single-cell omics research can provide information on cell heterogeneity at all levels of the central dogma. This may help to reveal the role of osteocytes, osteoclasts, and osteoblasts in OP. In addition, single-cell omics can also understand the changes of cells at different stages of differentiation in different biological processes in a cell population [137]. This is not only conducive to the exploration of biomarkers, but also may provide new ideas for further explaining the pathogenesis of OP.
Simulation study on the effect of resistance exercise on the hydrodynamic microenvironment of osteocytes in microgravity
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Hai-Ying Liu, Chao-Hui Zhao, Hao Zhang, Wei Wang, Qing-Jian Liu
Bone is typically comprised of dense bone, cancellous bone, and tissue fluid. The osteon is the basic structural and physiological unit of dense bone, and it also has the highest bone density in the human skeletal system (Liu et al. 2020; Larcher and Scheiner 2021). The central tubular area of the osteon is called the Haversian canal, which contains arterial and venous capillaries that permit the transport of nutrients and metabolic waste needed for cell metabolism. The multi-layer circumferential lamellae around the Haversian canal consist of a complicated lacunar-canalicular system (LCS). The osteocytes are located in bone lacunae, and the adjacent osteocytes form a complex spatial mechanical signal transduction network through synaptic connections in the canaliculi. The LCS is an important channel for material exchange between osteocytes and capillaries in the Haversian canal (Kwon et al. 2010). The deformation of the bone matrix under loading can induce liquid flow in the LCS, and the mechanical signals produced by the liquid flow are perceived and responded to by osteocytes, thus regulating the activity of osteoblasts and osteoclasts to adjust bone mineral density to adapt to the current mechanical environment (Tovar et al. 2004).
Alveolar bone remodeling after tooth extraction in irradiated mandible: An experimental study with canine model
Published in Ultrastructural Pathology, 2018
Venni Heinonen, Timo J. Ruotsalainen, Lauri Paavola, Jopi J. Mikkonen, Pekka Asikainen, Arto P. Koistinen, Arja M. Kullaa
Bone remodeling process is performed by osteoclasts (bone resorbing cells) and osteoblasts (bone forming cells) at the bone surface. Osteocytes, most abundant bone cells, are believed to be responsible for the bone remodeling.10 Osteocytes react to dynamic and/or static loading such as gravity or exercise, and they are the most common cell type found in bone matrix, comprising more than 90% of all bone cells in mature bone. Osteocytes are derived from osteoblasts that are trapped under the mineralized bone matrix, and form a cellular network, called as lacunar-canalicular network (LCN), which allows communication between neighboring osteocytes, osteoblasts, and bone lining cells. Long dendritic processes of the osteocytes convey signals to the neighboring osteocytes and the cells of the bone surface.11 With this network, osteocytes control bone metabolism, and bone homeostasis (breakdown and formation of bone) by producing bone formation and/or resorption proteins.11,12