An average of 2.6 million red blood cells are produced each second by the bone marrow to replace those worn out and destroyed by the liver. Bones serve as a storage area for minerals such as calcium and phosphorus. When an excess is present in the blood, buildup will occur within the bones. When the supply of these minerals within the blood is low, it will be withdrawn from the bones to replenish the supply. The appendicular skeleton is composed of bones that anchor the appendages to the axial skeleton.
Long bones are longer than they are wide and work as levers.
Short bones are short, cube-shaped, and found in the wrists and ankles. Irregular bones are all others that do not fall into the previous categories. They have varied shapes, sizes, and surfaces features and include the bones of the vertebrae and a few in the skull. Bone Composition Bones are composed of tissue that may take one of two forms. Compact, or dense bone, and spongy, or cancellous, bone.