Technically, the digestive system (i.e., the full gastro intestinal tract) is considered as part of the “outside” of the body, acting as an external surface similar to the skin. The space that an object can travel through without crossing a cell membrane or entering blood or tissue is called “lumen”. So the same intuition as in the meme actually holds true here, too.
Technically, the digestive system (i.e., the full gastro intestinal tract) is considered as part of the “outside” of the body, acting as an external surface similar to the skin. The space that an object can travel through without crossing a cell membrane or entering blood or tissue is called “lumen”. So the same intuition as in the meme actually holds true here, too.