They grow all over the body, are cut, styled, removed, loved and hated: Hair. Yet hair has a not-so-unimportant function to perform. Since hair is perceived as unattractive on most parts of the body, it is often subject to the common fashion dictates.
What is hair?
Schematic diagram showing the anatomy and structure of human hair. Click to enlarge. By definition, hair is part of the skin; strictly speaking, like fingernails and toenails, it is considered a skin appendage. The visible hair, that is, the hair that emerges from the skin, is dead tissue. The hair root, from which the hair grows, is located in the dermis, i.e. in a middle or lower layer of the human skin. Hair grows through the skin to the surface. Hair is mainly composed of keratin and grows everywhere on the skin, but not on mucous membranes, moreover, not in the palms of the hands and soles of the feet, as well as on the lips and nipples.
Anatomy and structure
As mentioned earlier, hair is a horny thread composed of keratin and formed in the hair root. The hair consists of three layers, an outer cuticle (cuticula), a fibrous layer (cortex) that forms the basic substance of the hair, and the medulla (medulla). The hair is anchored to the dermis by the hair root. Hairs vary in thickness. While a single hair on the head is about 0.05 mm thick, the fine hairs on the body are much thinner, especially in women. Pubic hair, underarm hair and eyebrows, on the other hand, are about as thick as the hair on the head. If the hair has reached a certain age, it falls out by itself, in the case of head hair this is the case after about 2-6 years. Contrary to popular belief, hair grows at the root, not at the tip. Hair also does not grow back more after cutting or shaving, this is subjective perception.
Function and tasks
The functions and tasks of the hair still stem from the Stone Age, when man still wore fur. Although man no longer needs a coat today, the hair nevertheless fulfills a purpose. If the human being is cold, for example, the hair still stands up today (goose bumps) to protect the skin from the cold. The eyebrows still protect the eyes from sweat that runs from the forehead into the face (in Stone Age man, the over-eye bulge was even more pronounced). Hair transports sweat and sebum to the skin’s surface to cool the skin in hot weather, and regular sweating and secreting of sebum is also part of natural skin care. In addition, both armpit hair and pubic hair are carriers of odor and sexual substances that humans secrete. Mostly, however, this hair is removed today for fashion reasons. Psychologically, the hair on the head represents an important function in the self-realization and also in the sexuality of man. Today, many people find their natural hair unattractive and try to remove it permanently by all means, including laser therapies. However, natural body hair is not harmful.
Diseases and complaints
There are some diseases that can occur in relation to hair in humans. The best known disease on the hair is probably hair loss (alopecia). While hair loss in men with advancing age is usually part of the natural aging process, hair can also fall out due to disease and very suddenly. This can have a variety of causes, a medical clarification is absolutely indicated, because hair loss can also be a concomitant of serious diseases. However, a loss of up to 100 hairs per day is quite normal and harmless. Excessive body hair can also occur, usually in women due to illness. In this case, hormonal disorders may be present that lead to excessive male hair growth and may require hormone therapy. Hair can grow into the skin and become inflamed, and the hair root can also become inflamed (e.g. boils, carbuncles). Diseases related to hair always originate from the hair root, since hair itself is dead tissue (skin appendage). There are no diseases of the hair itself.
