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Hair I Warm Greetings to you all, With the next few newsletter we will focus on Hair. Everyone is aware of how important it is to possess a fine head of healthy hair. An abundant crop of hair, possessing body and sheen is a mark of health and beauty, which sets members of both sexes and both the young and the old apart from the crowd. As you know, the article is compiled from the “Life Science Course” and was originally written by Elisabeth and Robert McCarter. All mammals possess hair of some kind. Like the nails and the many sudoriferous(sweat) and sebaceous (oil-secreting) glands, the hair is considered to be an appendage of the skin. Some animals have smooth hair some stiff bristle-like outgrowths; still others, pointed spikes. Individual hairs are composed chiefly of a pithy, horny substance, a sclero-protein, a simple protein known as keratin. The amino acids of which keratin is composed are strung together in a more or less straight line, one after another. These lines of amino acids are called polypeptides. Keratin is a fibrous protein and fibrous proteins are strong, sturdy, and tough. This same kind of protein is also found in the fingernails and toenails. In humans the hair consists of a cylinder 1/400th inch in diameter. At the base of the cylinder, which consists of a shaft and a point, there is a “root” which is embedded in the skin in a kind of pouch-like depression called the hair follicle. Beneath this depression is the papilla, a kind of nipple which fosters the hair and builds new hair cells. The papilla might be called the “connecting link” between the hair, the blood, and the nerves, which service it. The shaft or outer part is pithy (called medullary substance). It is surrounded by a fibrous part containing pigment and this portion is, in turn, covered by a layer of epithelium scaly cells. Near the point, the pith begins to taper off to form the penetrating point of the hair shaft. In humans the hair begins to develop in the foetal period. By the sixth month, the tiny foetus is literally covered with fine hair, which is termed the laguno. Following birth, the laguno is rapidly shed and is replaced by hair in all the familiar places and in the rather precise forms: coarse hair over the cranium and eyebrows and fine, downy-like hair over the rest of the body, the latter often being fine as to be almost invisible to the naked eye. At puberty certain changes are evidenced. Coarse hair begins to develop in the armpits and over the pubic or groin area in both males and females. In males the hair begins to grow more coarse over the upper lip and about the lower portion of the face and, if unshaved, quickly forms a beard. The rate of growth of the hair varies according to age, health of the individual, and the length of the hair. When hair is cut short, for example, it can grow as much as 1.9 cm and even more in a month but by the time it is 30 cm in length, its rate of growth can be reduced by as much as one-half, all other things being equal, of course. The hair of young people grows faster than that of older people, with the fastest growth being found in women, especially from 16 to 24 years of age, this latter age being about the time when most humans are said to reach full maturity. The type of follicle determines the identifying characteristics of the hair in different races. The black woolly hair of Blacks, Papuans and Melanesians grows from a curved follicle which imparts a spiral twist to the hair. This kind of hair growth appears flat or taper like when cross-sectioned and viewed microscopically. The characteristic straight, coarse, long and almost always black hair of the Chinese, Japanese, Eskimo, and American Indians grows from a straight follicle and this type of hair is round in cross section and possesses a plainly visible pithy centre. The hair of other group types, including those of European ancestry, is often wavy and somewhat intermediate in texture between the straight and woolly types. This latter kind of hair also grows from a straight follicle, but it is oval in cross section, this shape giving it greater or lesser tendency to curl. Next week we will discuss the variations in pigmentation and also some common disorders. Until next week then, Elise