<P> The skeletal system serves many important functions; it provides the shape and form for the body, support and protection, allows bodily movement, produces blood for the body, and stores minerals . The number of bones in the human skeletal system is a controversial topic . Humans are born with over 300 bones; however, many bones fuse together between birth and maturity . As a result, an average adult skeleton consists of 206 bones . The number of bones varies according to the method used to derive the count . While some consider certain structures to be a single bone with multiple parts, others may see it as a single part with multiple bones . There are five general classifications of bones . These are long bones, short bones, flat bones, irregular bones, and sesamoid bones . The human skeleton is composed of both fused and individual bones supported by ligaments, tendons, muscles and cartilage . It is a complex structure with two distinct divisions; the axial skeleton, which includes the vertebral column, and the appendicular skeleton . </P> <P> The skeletal system serves as a framework for tissues and organs to attach themselves to . This system acts as a protective structure for vital organs . Major examples of this are the brain being protected by the skull and the lungs being protected by the rib cage . </P> <P> Located in long bones are two distinctions of bone marrow (yellow and red). The yellow marrow has fatty connective tissue and is found in the marrow cavity . During starvation, the body uses the fat in yellow marrow for energy . The red marrow of some bones is an important site for blood cell production, approximately 2.6 million red blood cells per second in order to replace existing cells that have been destroyed by the liver . Here all erythrocytes, platelets, and most leukocytes form in adults . From the red marrow, erythrocytes, platelets, and leukocytes migrate to the blood to do their special tasks . </P> <P> Another function of bones is the storage of certain minerals . Calcium and phosphorus are among the main minerals being stored . The importance of this storage "device" helps to regulate mineral balance in the bloodstream . When the fluctuation of minerals is high, these minerals are stored in bone; when it is low it will be withdrawn from the bone . </P>

Attaches bones to bone and muscle to bones