The complex structure of ligaments and tendons that support our joints provides stability. They are composed of collagen, the most abundant protein in the body. Their tough, collagenous structure give the joint strength. This structure, however, also causes these tissues to have poor blood supply, making the joint prone to chronic conditions.
Every time you move, your muscles contract and relax. This process only takes a few seconds, but it is actually a quite complex process. Every activity in our body is controlled by muscles: breathing, circulation of blood, digestion. Even a simple smile is a result of muscle action. Muscles also help keep our body warm, maintain posture, and stabilize bones and joints. The body contains several types of muscles, some that work involuntarily, such as heart and organ muscles, and skeletal muscles that work primarily through voluntary action that is controlled consciously.