Hair Loss Causes


Hair Structure & Functions


Hair LossThere are approximately 5 million hair on the whole body. Of these, about 150,000 are found on the scalp. The only parts of our body where there are no hair follicles are the palms, soles, lips, tip of the penis, clitoris, and labia minora (small "lips" of the vagina).

Each hair grows from a pocket in the skin called the hair follicle. The number of hair follicles is fixed at birth. During its growing phase, the follicle has a bulb-shaped bottom, the center of which is called the dermal papilla (P). The papilla is fed by very small blood vessels, which bring it food and oxygen and take wastes away. The papilla is highly sensitive to hormones. It is here that hormones and chemicals secreted by the body (or ingested as a medicine) work on the hair, making it grow faster, slower, or not at all The cells in the hair bulb divide every 23-72 hours, the faster than any other cell of the body. Sebaceous glands surrounding the hair root secrete oil (sebum) while salt-water (perspiration) is secreted from nearby sweat glands. The sebum protects the hair and keeps it shiny and waterproof, while the sweat is a way for the body to cool down if it's too hot.

Hair Functions :

The purpose of hair is to keep the warmth in. Warm-blooded mammals require a warm body temperature to survive (cold-blooded animals, like snakes and other reptiles, metabolize and survive at "room-temperature" and thus neither need, nor have, hair). The densely packed hair of mammals (fur) plays an important role in keeping warm.

A tiny hair muscle attached to each hair follicle, called the arrector pili, contracts when in a cold environment (or when fearful). This causes the hair to be pulled downwards so it stands up straight (goose-bumps or gooseflesh), and warm air is actually trapped between each hair. This functions like a layer of clothing, keeping warmth in.
Humans, however, have lost most of our dense fur, so even though one still gets goose-bumps, and the hair can stand on end, the keep-warmth-in phenomenon no longer works.

Anatomy of Hair :
Hair Loss Hair is actually composed of a protein called keratin (about 88%). It's the same protein that is also found in nails and in skin. Keratin starts out as a soft substance arising from the follicle and keratinizes (hardens) as it rises up and out into the hair shaft. Keratin is insoluble, very tough, and highly elastic.

A strand of hair has three layers: - The outermost layer is called the cuticle. It is made up of transparent, protective scale-like cells, and acts to protect the inner layers. Most hair conditioning agents tend to affect this cuticle.
- The innermost layer is called the medulla, and is composed of large baggy keratinized cells interspersed with air pockets that give hair its elasticity.
- Between these two layers is the cortex. The bulk (75-80%) and strength of hair is from this compact area of cells. The cortex gives hair its strength and elasticity and is responsible for its color.

Hair Growth Phases :

Hair grows in cycles of various phases :
- Anagen is the growth phase. The hair in this phase is long, well rooted and fully pigmented. In this phase the hair grows approximately half an inch a month.
- Catagen is the involuting or regressing phase. The pigment content declines, the hair follicle separates from the dermis and moves upwards towards the epidermis. Since the hair is cut off from the blood supply and cells that produce new hair, it is now called CLUB hair. The name club hair is given because the bulb of hair looks like a club-shaped mass.

- Telogen the resting or quiescent phase. The follicle in dermis regrows and pushes out the club hair.
- Exogen or a shedding phase, that is independent of anagen and telogen. Prior to the start of cycling is a phase of follicular morphogenesis (formation of the follicle). Normally up to 90% of the hair follicles are in anagen phase while, 10-14% are in telogen and 1-2% in catagen. Contrary to popular myths and superstitions, hair does not grow thicker or faster when cut or shaved. Nor does it grow after death. In one year, the body produces seven miles of hair 350 miles in an average lifetime.