The skin is the answer. It is an organ of protection.
The skin is made up of two layers namely the epidermis and the dermis. Under the dermis is found hypodermis which is subcutaneous fatty tissue.
The skin has three major functions namely protection, regulation and sensation. When the skin is broken, i.e. wounded, all these functions are affected.
The skin acts as a barrier, providing protection from radiation from the sun, mechanical impacts, pressure and changes in temperature, as well as from microorganisms and chemicals.