The movement systems: skeletal and muscular
Nick Draper, Helen Marshall in Exercise Physiology, 2014
Bone is deceptively light due to the numerous spaces within its structure. Depending on the size and distribution of these spaces, bone can be classified as either compact (dense) or spongy (trabecular, cancellous). Compact bone which has minimal gaps and spaces, accounts for 80% of the bone mass of an adult skeleton. It forms the hard outer regions of all bones, and the diaphysis (shaft) of long bones, and gives them a smooth, solid appearance. Compact bone is arranged in functional units called osteons, or Haversian systems, which consist of a central canal encircled by concentric rings (lamellae) of a hard intercellular substance. Small spaces (lacunae) exist between these rings and enclose osteocytes (mature bone cells). Nutrients and waste products are transported to and from osteocytes through a network of canals (canaliculi) connecting the lamellae. Compact bone provides strength and protection for bones and is a particular feature of long bones (see Figure 5.3).
Bone and Cartilage
George W. Casarett in Radiation Histopathology: Volume II, 2019
The internal structure of compact bone differs from that of spongy bone in the development of haversian systems (osteons) as the structural units of compact bone (Figure 1D). The osteons are oriented chiefly to the long axis of the bone. The axis of an haversian system is the haversian canal (generally from 22 to 110 um in diameter), which contains within its loose connective tissue one or more blood vessels (mostly capillaries and postcapillary venules, occasionally an arteriole), lymphatics, and nerves. Each haversian canal is surrounded by from 4 to 20 concentrically arranged lamellae. Each osteon contains large numbers of osteocytes in their individual lacunae, and the extravascular canaliculi radiating from the canal and interconnecting with the lacunae and other canaliculi of the osteon. Tissue fluids diffuse between the vessels in the canal and the osteocytic and lamellar surfaces through these canaliculi. Haversian canals often open into the marrow cavity.
Bone, Muscle, and Tooth
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
Both cortical and trabecular bone consist primarily of lamellar bone in which the collagen fibers are highly organized and arranged in parallel layers. In contrast to lamellar bone, woven bone refers to immature bone in which the collagen fibers are randomly oriented and lacks the structural organization of lamellar bone. Woven bone is rapidly formed, often in response to injury and, in the normal setting, is replaced by more structurally sound lamellar bone. The simple use of transmitted polarized light in routine, decalcified, paraffin-embedded sections of bone is an effective way for the bench pathologist to visualize the orientation of collagen fibers. In dogs and nonhuman primates, the cortical bone is organized in concentric layers around a central channel. This unit is referred to as an osteon or Haversian system. In contrast, rats and mice lack or have poorly developed Haversian systems.
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).
Multi-scale numerical simulation on mechano-transduction of osteocytes in different gravity fields
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Chaohui Zhao, Haiying Liu, Congbiao Tian, Chunqiu Zhang, Wei Wang
Liquid flow can hydromechanically stimulate osteocytes, bring nutrients required for metabolism and remove metabolic waste. In order to study the fluid-solid coupling interaction between osteon to osteocyte structure and tissue fluid and the mechanical conduction mechanism of TES, symmetrically distributed canaliculi in the model, and there was only one canaliculus with TES. The nephograms of liquid flow velocity were obtained in microgravity, Earth’s gravity and 3 g gravity (working conditions c01, c11, c31) conditions, as shown in Figure 2. The results showed that the liquid flow velocity in the canaliculi was significantly higher than that in the lacunae. In the Earth’s gravity (c11) and the high-G gravity (c31) conditions, the maximum liquid flow velocity in the canaliculi was 310% and 739% of that in microgravity(c01), respectively. The results suggest that the liquid flow velocity depends on the gravity fields, and it is affected by TES. The liquid flow velocity in the canaliculi with TES was noticeably higher than that in the canaliculi without TES.
Simulation of the mechanical behavior of osteons using artificial gravity devices in microgravity
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Hao Zhang, Hai-Ying Liu, Chun-Qiu Zhang, Zhen-Zhong Liu, Wei Wang
After a long period of evolution and natural selection, the structure and functions of the human body have almost perfectly adapted to the Earth’s environment (Darwin 1963). Bone tissue plays a critical role in supporting the human body. The osteocyte network in bone tissue senses the external load and other information from the environment to regulate bone reconstruction activities. This process achieves the optimal state of bone mineral density corresponding to the requirements of the external environment. Bone metabolism and mechanical signal transduction are closely related to the microenvironment of osteocytes. Fluid in the LCS is the carrier of material exchange between osteocytes and the blood (Price et al. 2011). Bone is generally composed of compact bone distributed in the outer layer of bone and cancellous bone in the inner layer of bone. Dense bone is composed of the outer and inner circumferential lamellae and the osteons between them. In contrast, cancellous bone is composed of intertwined trabeculae (Shi et al. 2016).
Related Knowledge Centers
- Bone
- Cytoplasm
- Haversian Canal
- Lacuna
- Osteocyte
- Osteology
- Metabolism
- Osteoblast
- Bone Canaliculus
- Nutrient