Final answer:
Nutrients reach the skin's surface through the process of diffusion, where they move from areas of higher concentration to areas of lower concentration.
Step-by-step explanation:
Nutrients reach the surface of the skin (epidermis) through the process of diffusion. This biological process allows for the exchange of nutrients and waste products between the blood and tissue, as well as between air and blood in the lungs.
Diffusion is essential in single-celled organisms and continues to play a significant role in multicellular organisms, despite the advent of circulatory systems that help transport substances over larger distances. The epidermis relies on this process, as nutrients filter through from the underlying blood vessels in the dermis layer up to the outer layer of the skin.