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Abstract Bone is a special form of connective tissue, which unlike most other tissues is physiologically mineralized. Despite its inert appearance, bone is a highly dynamic organ that is continuously resorbed by osteoclasts and neoformed by osteoblasts. Bone is a multifunctional tissue which serves as mechanical support and protection, is an essential part of hematopoiesis and mineral metabolism, and has a role as an endocrine organ. Bone Function As well as contributing to the body‟s overall shape, the skeletal system has several key functions, including: Support and movement; Protection; Mineral homeostasis Blood-cell formation Triglyceride storage Bone Cells Bone cells make up about 10% of total bone volume. There are four types of cells: Osteoprogenitor (Stem) Cells Osteoblasts Osteocytes Osteoclasts Blood vessel structure and functions Blood and lymphatic vessels pervade almost all body tissues and have numerous essential roles in physiology and disease. The inner lining of these networks is formed by a single layer of endothelial cells, which is specialized according to the needs of the tissue that it supplies. Whereas the general mechanisms of blood and lymphatic vessel development are being defined with increasing molecular precision Blood vessels organize into tree-like structures. Large arteries carry oxygenated blood away from the heart and branch into smaller calibre arterioles that feed into extensive capillary networks. Venules drain capillaries and converge into larger veins to return oxygen- depleted blood to the heart. Blood is transferred via the pulmonary artery to the lungs for reoxygenation. The interaction betweem bone and vascular system There is astrong relation between bone and vascular system, the concept of the bone–vascular axis may explain, for example, the relationship between bone metabolism and vessel wall diseases like atherosclerosis and arteriosclerosis, with potential involvement of a number of cytokines and metabolic pathways. A very important discovery in bone physiology is the bone marrow (BM) niche, the functional unit where stem cells interact, exchanging signals that impact on their fate as bone-forming cells or immunecompetent haematopoietic elements. This new element of bone physiology has been recognized to be dysfunctional in diabetes (so-called diabetic mobilopathy), with possible clinical implications. |