The skeletal system has many functions, most of which we do not realize are taking place. These various functions enable organisms to grow larger, move better, protect effectively, and heal faster. Functions of the skeletal system include support, protection, movement, mineral and energy storage, and blood-cell formation.
Support
Without the support of the skeletal system, animals would all be confined to smaller, more compact designs. In addition, animals mainly would inhabit waters where gravity would not create much strain on internal organs. Many bones of the body provide support, but it is especially true of the long bones. For example, the long bones in legs help support the trunk. Bones other than long bones also provide support. For example, the first vertebra supports the skull, the second vertebra supports the first, and so on. With the support of bones, animals were able to develop into larger organisms with greater chest and organ capacities. Even the massive bones found from dinosaurs prove that large growth is not possible without strong bones.
Protection
An important function of the skeletal system is the protection of vital internal organs. The skull protects the brain just as the rib cage protects the heart, lungs, and abdominal organs. Being encased and protected allowed these organs to develop and to increase in size and performance. Without protection from bones, a simple bump to the head or abdomen could be a fatal injury.
Movement
In combination with the muscular system, the skeletal system provides for bodily motion. Skeletal muscles are attached to bones by tendons. The tendons act as a lever to move bones. All bones are pulled by muscles, not pushed, so each moveable bone must be strong enough to withstand the pulling force exerted upon it.
Mineral and Energy Storage
The outer layers of bony tissues are used for the storage of minerals, primarily calcium and phosphorus. Deposits and withdrawals of mineral ions from bone are continuous, which helps to maintain blood levels of calcium and phosphorus. Yellow marrow, found in the shaft of long bones and other mature bones, consists mostly of fat and serves as an energy reserve.
Blood-Cell Formation
The inner core of bone is a soft tissue called bone marrow. Red marrow is a major site of blood cell and platelet formation. Platelets help to heal wounds by surrounding injury sites and stopping external blood flow, eventually forming a scab. Blood cells produced by the marrow are red or white. Red blood cells carry oxygen to tissues by way of the circulatory system. Meanwhile, white blood cells identify foreign and potentially infectious cells in the body, which they attack and destroy.
