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Musculoskeletal System

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The musculoskeletal system is an organ system that gives humans the ability to move, using the muscular and skeletal systems. It provides form, support, stability, and movement to the body. The musculoskeletal system is made up of the body's bones (the skeleton), muscles, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together. Its primary functions include supporting the body, allowing motion, and protecting vital organs. Most importantly, the system provides form, support, stability, and movement to the body. For example, the bones of the skeletal system protect the body's internal organs and support the weight of the body. The skeletal portion of the system serves as the main storage depot…show more content…
PTH is released in response to low blood calcium levels. It increases calcium levels by targeting the skeleton, the kidneys, and the intestine. In the skeleton, PTH stimulates osteoclasts, which are cells that cause bone to be reabsorbed, releasing calcium from bone into the blood. PTH also inhibits osteoblasts, cells which deposit bone, reducing calcium deposition in bone. In the intestines, PTH increases dietary calcium absorption and in the kidneys, PTH stimulates reabsorption of the calcium. While PTH acts directly on the kidneys to increase calcium reabsorption, its effects on the intestine are indirect. PTH triggers the formation of calcitriol, an active form of vitamin D, which acts on the intestines to increase absorption of dietary calcium. PTH release is inhibited by rising blood calcium levels. Levels of estrogen peak during puberty and decrease with age. Until about age 30, a person normally builds more bone than he or she loses. After age 35, bone breakdown overtakes bone buildup, which causes a gradual loss of bone mass. Once this loss of bone reaches a certain point, a person has osteoporosis. In osteoporosis, bone tissue becomes brittle, thin, and spongy. Bones break easily, and the spine sometimes begins to crumble and
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