Re: Why doesn't soap dissolve epithelial tissue?

In the interest of a quick turnaround, I have not researched this issue 
in great depth, but I think I have a fairly good intuitive grasp of what is 
going on and have been encouraged by suggestions made by my 
colleagues at Valencia Community College in response to my 
request for help with your question. Suffice it to say that yes, soap 
does disrupt cell membranes; that's its purpose in the DNA 
demonstration you saw, it releases the contents of the cheek cells 
(including the DNA).

If you think about it, you will quickly realize that soap irritates the 
mucous membranes that line the inner surfaces of your nose and 
mouth. Soap will also burn your eyes. This effect is related to the 
disruption of membranes. No, you will not dissolve your cheeks by 
swirling dish soap in your mouth.

First of all, if you are talking about concentrated dish soap (the way it 
comes from the bottle) it would be a very difficult thing to do as it 
would be very objectionable. And yes it would harm your mucous 
membranes. But, just like soap in the dishwater, if will run out of 
effectiveness. This is because of how it acts. It uses itself up in the 
emulsification of lipids. So, it would only dissolve your membranes 
for as long as you could hold it in your mouth or as long as it could 
keep supplying the bipolar molecules that emulsify the lipids by 
surrounding them in micelles, which ever comes first.

Radiator antifreeze is dangerous because it is toxic and tasty 
(especially to dogs). Soap is not dangerous because even though it 
is toxic to cell membranes, it tastes terrible and burns. It also works 
fairly slowly.

The mucous membranes that line openings into the body (such as 
the mouth, nose, anus, and vagina) are made of a many-layered cell 
sheet (called stratified squamous epithelium). The outer layers of 
cells become flattened and lose their contact with the blood vessels 
and nerves in the connective tissue below them. Consequently, their 
destruction by soap could go relatively unnoticed for quite a while. 
The cells in these outer layers are constantly being shed and, in the 
case of those in the mouth (and to some extent in the nose) are 
swallowed. Remember, rinsing with salt water was enough to pick 
up a significant sample for the DNA demonstration. Mucous 
membranes provide a moist but slippery and reasonably protective 
barrier in the locations where they are found.

Skin is also made of stratified squamous epithelium but, unlike the 
epithelium that comprises the mucous membranes, its outer layers 
are dried into a dead, protein-rich sheet called the stratum corneum. 
This material also makes up the substance of hair, fingernails, the 
"pads" on your dog's feet, and the material that covers the bone core 
of cow's horns.

The stratum corneum provides a relatively impervious water barrier 
and is not much affected by soap, as the cell membranes are already 
dead. Flakes of this, so called, "horny" material are constantly being 
shed from the skin of humans. If this happens in excess on the scalp 
we call it dandruff.

Incidentally, if you soak your skin in water for a long time, water will 
soak into the horny layer and cause it to expand. Since it is firmly 
attached to underlying connective tissues (the dermis of the skin) that 
are quite elastic, the excess corneum surface area is accommodated 
by wrinkling of the skin producing the "prune fingers" effect.

I'm sure that if you held wet, concentrated soap next to your skin or 
mucous membranes for a long time, damage would be done and it 
wouldn't be pretty. But what are the chances?

As for your cup full of phospholipid micelles...  they are pretty much 
"soap" themselves. Your use of the term 'dissolved' is not quite 
accurate, either in this situation or in reference to phospholipid 
membranes. The term 'disrupt' is more descriptive of what is going 
on. And yes, I would say that if you mixed soap or phosphate 
detergent with phospholipid micelles the micelles would be 
disrupted.

Remember, these musings are not heavily researched, indisputable 
truths but my best, intuitive reasoning on the subject based on many 
years of study and experience.

Hope this answers your questions.