Your lips and your anus have something in common that you were probably never taught in school: they are the same type of tissue. 😳
It is called mucosa, a stratified squamous epithelium, and it marks the two opposite ends of the same path: your digestive tract. That is why neither has sweat glands, which explains why they dry out so quickly. And that is also why they are packed with nerve endings, much more sensitive than the rest of your skin.
The difference lies in the job they do. The lips receive food with the help of facial muscles. The anus sends it off, controlled by sphincters. Two different doors in the same hallway, made of the same material. 🧬