Hair - Functions, structure and Abnormalities
Know your Body

Hair : The Crowning Glory

Dr.Surya Rao Poodipeddi profile Authored by Dr.Surya Rao Poodipeddi on 18 Jan 2014 - 11:08.

Hair is a threadlike structure that grows all over the human body. Each hair grows out of a minute pit like portion called the hair follicle.

Hair structure: Hair is made of a root and a shaft. The root is embedded in the skin and the shaft emerges from the root and is the visible part above the skin. The growth stages of the hair cannot be tracked as it emerges from the follicle, and grows in length.

The shape of the shaft determines the nature of the hair -  straight hair, curly hair or wavy hair. A hair follicle is a pit deep in the skin from where it grows. At the base is a bulb called hair bulb which contains several cells each of which divides to produce new hair pushing it upwards which we see as the shaft. Each follicle has oilglands which produce a substance called sebum which is oily. The sebum helps maintain lubrication of the hair as well as the skin making it waterproof.

The root of the hair lies in a minute pit called the hair follicle. It has three layers which are circular in shape.The tough outer portion of the hair is called the cuticle. The middle layer is called the cortex and the inner layer is called the medulla. As the hair grows longer and longer the hair cells die and produce a protein called keratin.

Besides keratin the hair also contains a pigment called melanin. The pigment melanin determines the color of the well as the skin.

Hair growth: The hair growth in human body occurs at a rate of approximately one centimeter every month. The growth continues for about three years and then stops but the hair so grown stays and rests for a couple of years. As the new hair pushes upwards the old hair falls. Roughly 100 hairs fall every day which explains the fact that there is a continuous process of old hair falling and new hair coming up.

There is always a difference in the growth of hair between a male and a female. This is mainly governed by hormonal control. Females do not have hair above the lips and  on the chest.

The hair growth varies from person to person and also in gender. In most cases there is normal growth pattern of hair in either sex. However the pattern changes depending on hormonal control and also in some races like in African counties.

Abnormal hair growth in both genders:

Sometimes, among women we see hair growth in unwanted areas like lips and chest, ears and legs while there is absence of pubic hair or abundance of pubic hair. In some cases there may be lack of hair growth on the lips and pubis in males which is known as absent pubertal changes. All these variations are due to hormonal imbalances in either sex.

Similarly a bald male may not have hair on his head like. There may be selective distribution of hair on the head like in case of alopecia where there are patches of baldness. There may be excessive growth of hair in some persons who need to trim it frequently. In a female there may be uniform distribution and growth of hair on the scalp. There may be lack of hair or abnormal hair fall in some cases.

Baldness is the main condition directly affecting the scalp. Other conditions affecting hair indirectly through the skin are psoriasis and dandruff. In African countries the distribution of hair and its pattern are totally different from those in other countries. The hair assumes a silky appearance in those living in western countries. In western females the hair is blond, redhead or brunet type.

Hair has tremendous potential for business by selling hair in the form of wigs. The collections of hair in some temples are so huge that wigs and pig tails are manufactured in large scale and exported to other countries from India.


*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.