Musculoskeletal system provides the body movement or its parts in space. It consists of skeleton and skeletal muscles. With the help of a skeleton bo

Bone structure (chemical and microscopic)

Musculoskeletal system provides the body movement or its parts in space. It consists of skeleton and skeletal muscles. With the help of a skeleton body maintains a certain shape. It provides support throughout the body weight. Viscera are attached to it. The skeleton protects them from mechanical and other damage: for example, the brain and the sense organs are placed in the skull, the spinal cord — is in the spine.

Bones have a complex structure and chemical composition. In the living organism they contain 50% water, 28% organic matter (including 15% protein and 10% fat) and 22% inorganic — mineral substances represented by compounds of calcium (99% of all minerals), phosphorus, magnesium and other elements. Dried and degreased bone is composed of 30% organic, 60% — of inorganic substances and 10% — water.

Cells form 1/3 part of bones, and the intercellular substance — 2/3. They are very strong. For example, the femur can withstand loads of up to 1500 kg. The bones are not only solid, but also elastic due to fibrous proteins of the intercellular substance. There is a certain age relationship between the amount of protein and minerals in the bones. For example, children's bones are more elastic, because they contain more protein ossein than minerals. In the elderly, on the contrary, the mineral content is greater. Because of this, their bones have less elasticity and often fracture with injuries.

Bone cells (diagram 15), called osteocytes participate in the building of bone. Osteocytes are arranged concentrically, forming a circular system (osteons). Taken from http://worldofschool.org

Diagram 15. Microscopic structure of bone: 1 — the periosteum; 2 — ring system; 3 — bone cells; 4 — cortical bone; 5 — cancellous bone; 6 — blood vessels and nerves; 7 — articular surface covered with cartilage; 8 — the head of the tubular bones; 9 — the body of the tubular bones
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Questions:
  • Explain the importance of the human musculoskeletal system.

  • Describe the structural features of the musculoskeletal system.

  • What are the functions of the musculoskeletal system?

  • Show the relationship of the microscopic structure of bone and functions.

  • What features of the structure and chemical composition of human bones provide their strength and elasticity?