In order to understand osteoporosis, it is important to learn about bone. Made mostly of collagen, bone is living, growing tissue. Collagen is a protein that provides a soft framework, and calcium phosphate is a mineral that adds strength and hardens the framework. This combination of collagen and calcium makes bone strong and flexible enough to withstand stress. More than 99 percent of the body's calcium is contained in the bones and teeth. The remaining 1 percent is found in the blood.
There are two types of bone found in the body - cortical and trabecular. Cortical bone is dense and compact. It forms the outer layer of the bone. Trabecular bone makes up the inner layer of the bone and has a spongy, honeycomb-like structure.