<span>There are three parts of the body that will change suggesting a systemic disease. The first is the hands, which contain may blood vessels and a significant amount of skin surface. Nerves in the body might show signs of a systemic disease. Finally, muscles, tendons and ligaments might swell or otherwise show signs of bodily stress.</span>
I guess that is: Within the capillaries of the lungs, gases are exchanged by diffusion; O2 diffuses from the alveolus to the bloodstream and CO2 diffuses from the bloodstream to the alveolus.
