The skeleton, made up of all the body's bones, provides strength, stability, and a frame for muscles to work against in producing movement. Bones are both strong enough to support our weight and light enough to allow us to move. They protect delicate internal organs and store important minerals. Bones come together to form joints, most of which are in constant motion.
Muscles make up almost half the weight of the human body.
Skeletal muscles work together with bones to provide the power that enables us to move. Tendons attach muscles to bones, and ligaments surround joints and connect one bone to another. The ends of bones are covered with cartilage, a smooth, tough, protective tissue that acts as a shock absorber and reduces friction. Skin also helps to regulate body temperature, senses painful and pleasant stimuli, and shields us from the sun's harmful effects. Skin disorders include the minor problems of dry or thin skin, boils, and blisters, as well as more troubling conditions such as psoriasis and eczema.