Subject: Why doesn't soap dissolve epithelial tissue?

I saw a demonstration at school where we swirled salt water in our mouths and 
spit that into a cup.  Then we mixed a watered-down solution of dish soap in 
the spit solution.  Then we added isopropyl alcohol to precipitate the DNA.

I understand how everything worked with the exception of the soap.  If I swirl 
dish soap in my mouth, will my cheeks eventually completely dissolve?  Would my 
skin eventually dissolve if I kept my arm in a tub of soapy water? 

The only thing I can figure is that there is some type of epithelial glycocalyx 
(or something like that) on the apical side of the cells, so that side is 
protected, and then the tight junctions between the cells prevent soap from 
getting to non-apical surfaces.  When we add soap to the mixture of cells in 
the cup though, the cells are free in solution, so the non-protected sides are 
exposed and the membranes dissolve.  Is this true?  

I searched on this site, and only found pages that talk about saponification of 
fatty acids (talking about why alkali solutions feel soapy) or about the drying 
effects of soap.  I'm more curious about how epithelial cells protect their 
membranes from being dissolved.  If I had a cup full of phospholipid micelles, 
would soap dissolve them?  If so, why doesn't our skin dissolve as well?  If 
not, why doesn't the soap dissolve them?  Thanks for taking the time to help!

Re: Why doesn't soap dissolve epithelial tissue?