Every day, a barrage of advertisements for various cosmetics, oils and ointments assault our eyes and ears, all claiming to "let your skin breathe." But does your skin actually "breathe"? Does it really take in enough oxygen to keep you alive?

Not unless you're an amphibian, an earthworm or a Julia Creek dunnart. Although it can't perform the functions of respiration, your skin can absorb fat-soluble substances, including vitamins A,D, E and K, along with steroid hormones such as estrogen. Many menopausal women, for example, have estrogen patches to thank for their relief from hot flashes, while nicotine patches have relieved cravings for many smokers trying to kick the habit. So, while the skin can't breathe, it can take substances from the outside and bring them in, including a little oxygen.

The skin and its appendages, such as hair and nails, make up the integumentary system. The word integumentary comes from Latin, meaning "to cover," and that is the skin's main purpose -- to keep the world out and our internal organs protected. By its very nature, skin does not help us breathe. The skin is the largest organ, making up about 12 to 15 percent of our body weight [source: Maricopa]. In addition to protection from outside toxins, skin offers temperature regulation and sensory reception.

What does help us breathe is the respiratory system. The respiratory system is responsible for getting oxygen to our blood and removing carbon dioxide from the body. When we inhale, we take in oxygen through our mouth and nose and into the lungs. In the lungs, the oxygen flows into the blood through the arteries, while veins deliver carbon dioxide back to the lungs. From the lungs, we exhale the carbon dioxide back out into the atmosphere, and the process begins again.

So why might we be led to believe that oxygen can pass through the skin?