brasheranatomy1skeleton

THE SKELETAL SYSTEM--PART 1

The skeletal system is basically responsible for support of the body and protection of many of its vital organs. Along with the muscular system, it also functions in body movement. Muscles attach to the bones by tendons and the bones act as levers to move the body. Other litte-known functions of the skeletal system include fat storage (in the yellow marrow), storage of minerals such as calcium and phosphorus, and blood cell formation that takes place in the red marrow. Microscopically, there are two types of bone: cancellous bone, which is also called spongy bone, and compact bone. Cancellous bone is found in all bones and actually looks like a sponge. The ends of a long bone contain cancellous bone, while the shaft of a long bone contains compact bone. The microscopic structure of compact bone is the most complicated. It contains the following structures: 1) Haversian Canal--space containing a blood vessel 2)Lacunae--spaces containging bone cells, called osteocytes 3)Canaliculi--small tubes containing capillaries nourishing the osteocytes 4)Lamellae--concentric rings of matrix encircling the Haversian Canal 5)Haversian System--one Haversian Canal and its associated osteocytes 6) Volkmann's Canals--tubes containing blood vessels that connect Haversian systems, or osteons