The skin performs six primary functions which include, protection, absorption, excretion, secretion, regulation and sensation.
Protection. The skin functions as our first line of defense against toxins, radiation and harmful pollutants.
Absorption.
Excretion.
Secretion.
Regulation.
Sensation.
The answer is Social Gerontoloogy
I'm not sure, but I think that its your skin that protects the internal tissues.