Without such care, the complex organization of the skin breaks down, making it and the body it protects susceptible to injury and disease. Thus, the body s coverall organ is as fragile as it is seemingly unyielding. The skin is the largest organ of the body and is as indispensable as the body s other major organs. But the skin is perhaps the organ that brings us closest to an understanding of organ function, because its anatomy and function can be partially observed by the naked eye. In addition to its ability to communicate internal physiological information, like the presence of fever, the skin also reacts to external stimuli, like sun exposure, toxins, and even psychological stimuli.
Skin is made up of two primary layers that differ in function, thickness, and strength.
From outside to inside, they are the epidermis and its sublayers, and the dermis , after which is found subcutaneous tissue, or the hypodermis. The two layers are further differentiated by their respective amounts of hair follicle , pigmentation , cell formation, gland makeup , and blood supply. Moreover, these layers are present in the two general types of skin, thin and hairy, and thick and hairless. The former is more prevalent on the body, while the latter is found on parts of the body that are used heavily and experience extreme friction, like the palm and the heel. The epidermis, the outermost layer of skin, is thin but complex.