The areas of the body that we consider sterile are those part of the body that are not exposed to the environment. Our skin is home to vast numbers of several different types of microbes as or the openings that lead deep within. All of the organs inside our body should be considered sterile with the exception of the lumen of the G.I. tract. While the intestines are an organ inside us it houses materials that where once exposed the the environment and is home to microbes as well. Now there are times that bacteria can penetrate our organs and become infected but under normall circumstances you consider them sterile.