The hair is a continuation of the scalp, formed by a fiber of keratin and consisting of a root and a stem. It forms in a follicle of the dermis, and is the characteristic feature of thin or thin skin. The difference between the keratin of the stratum corneum and the keratin of the hair is that in the hair the cells are always joined with others, giving rise to a very hard keratin. Each of the hairs consists of a root. It is a hair follicle and on a stem that projects upwards above the surface of the epidermis. The root enlarges in its base. The papillary zone or dermal papilla is composed of connective tissue and blood vessels, which provides the hair with the substances necessary for its growth.
This is distributed over almost the entire body surface, except when the palmoplantar surfaces, navel and mucous membranes. In an adult, the approximate number of films is about five million, distributed unevenly throughout the body. In the head there are around a million, being between 100,000 and 150,000 in the scalp. The hair of the head maintains the corporal heat of this and offers a high level of protection against shock. The eyelashes protect the eyes that diminish the quantity of light and the dust that can penetrate in these; and the eyebrows protect the eyes from the sweat that can drip down the forehead.
This is constituted by keratin (fibrous protein), which contains a high amount of quantity within which is the amino acid that has a sulfur atom. “Keratin chains are arranged in parallel”, 1 of which are held together by three types of links:
Saline bridges between an acid and a base
Water has the capacity to break the temporary path of salt bridges and hydrogen bridges.