Connective tissue is found throughout the body and includes fat, cartilage, bone and blood. The main functions of the different types of connective tissue include providing support, filling in spaces between organs, protecting organs and aiding in the transport of materials around the body.

Connective tissue is composed of living cells and protein fibers suspended in a gel-like material called matrix. Depending on the type of connective tissue, the fibers are collagen fibers, reticular fibers, elastin fibers, or a combination of two or more types. The type and arrangement of the fibers gives each type of connective tissue its particular properties.

Of the three types of protein fibers in connective tissue, collagen is by far the most abundant, and accounts for almost one third of the total body weight of humans. Under the microscope, collagen looks like a rope with three individual protein fibers twined around...