Look here! It;s me, your hair speaking. Are you surprised? You can feel my presence on your scalp. You will also find me on all the major visible surfaces of your body – eyebrows, above lips, cheeks, chin, arm pits etc.
Source: Wikimedia Commons
Source: Wikimedia Commons
Men and women are worried about my (hair) health. Remember that only my healthy presence could enhance beauty and youthfulness. I am totally responsible for your gender identity. Women folk are very keen about my appearance. They are ready to spend more time in beauty spas or hair dressing saloons to improve my appearance.
Do you know that I have much more complicated anatomy than my outward appearance? It is always useful to understand the biology. My unique structure and functions will provide completely renewable growth. This article explains about the basics of my constitution and growth.
Hair Shaft
How I am Structured? I have two different structures. What you see on your scalp is known as hair shaft. It is nothing but the dead shaft seen above the scalp. These colored strands are attached to your scalp. It is my outward structure. Each hair shaft is made up of there essential layers i.e. cuticle, medulla and cortex. Cuticle is the outermost layer. Cuticle protects medulla and cortex. Simply cuticle is a transparent structure and only this layer gives shiny appearance. If this outer layer is not healthy then you will get dull appearance. Medulla is the innermost layer constituted by large size cells. Cortex constitutes the middle layer. Cortex possesses the protein called keratin and coloring pigments. It is the cortex that determines my strength and size.
Keratin: Protein Constituent
Do you know about hair shaft constitution? The main constituent is the wonderful protein called Keratin. This protein safeguards hair shaft from wear and tear. Your nails are also constituted mainly by keratin. You will also find keratin within the feather of a bird and in the claws of animals. The large molecules of keratin are constituted by tiny amino acid beads forming a chain like appearance. My other constituents include the pigment called melanin (responsible for hair color), certain fat, small quantity of vitamins and traces of minerals like zinc etc. My constitution also includes 10 to 15 per cent of water and this helps me to maintain my moisture and balance the biochemical and physiological properties.
Hair Follicle
The other part or structure is called follicle. This pouch like structure is sunken inside your scalp. The follicle is encircled by two protective sheaths i.e. inner sheath and outer sheath. The hair shafts are well protected and molded by these two sheaths. The follicle also provided with an oil gland called sebaceous gland. The sebaceous gland is responsible for the production of sebum – a natural hair conditioner. You will produce sebum after you attain puberty. The women folk produce lesser sebum as they grow older. The men folk also produce some what lesser sebum but it is more when compared with women folk.
The hair shaft has its root in the follicle. Hair shaft comes out from the follicle. At the bottom there is a projection called hair papillae. The hair papillae have tiny blood capillaries to nourish my hair root. The thickness of the shaft totally depends up on the follicle size. It is the follicle that is responsible for my health.
However the follicle could support its nourishment till the shaft is pushed out of the follicle base. Afterwards the shaft could not derive nourishment from follicle and hence they die. After the death the shaft gets transformed into harder protein called keratin. Simply understand that only the bottom portion of your shaft is nourished by follicle.
Follicle Development
You will be surprised to learn that the development of hair follicles takes place in the fetus itself during 22nd week (child development stages). The child will have around on million follicles on the scalp. The more you grow older the density of follicles decrease.
Hair Follicle Cycle
Have you ever tried to understand my (your scalp hair) growth rate per year? My growth at your scalp will be around six inches per year. You will get hair growth of 0.03 to 0.04 mm only and you will get this much hair growth. You will have random hair growth or hair loss. It is not cyclic or seasonal. Simply understand that in a given period of time you will have a random number of hair growth and shedding on your scalp. Your hair growth involves three stages: (1). Anagen, (2). Catagen, and (3). Telogen.
Anagen
It is the active hair growth phase. There is active cell division at your hair roots. More and more new hairs are formed and your hair follicles push out the club hairs out of your follicles. Every 28 days you will get rapid hair growth around 1 cm. The hair grown during this growth phase will remain for about two to six years. Some of you might have felt problem of hair growing beyond certain length. It may be due to short phase of growth (Anagen). Some of you might be blessed with very long hair and reason is simply long phase of growth. Have you ever noticed that there is short active hair growth phase on your arm pits, limbs, eyelashes, and eyebrows? There is a very short active growth phase at these regions i.e., about 30-45 days. Active phase of growth is not warranted at these regions.
Catagen
It is the transitional phase. The Catagen is the phase that follows active hair growth phase called Anagen. Once your Anagen phase gets completed your hair undergoes a transitional stage. About three per cent of your hair undergoes this transitional process at any given period of time. This phase will lasts for about a period of three to four weeks. During Catagen your hair growth gets stopped. The outer sheath of your hair root undergoes shrinking process. There your hair gets attached firmly.
Telogen
It is the resting phase. The Telogen is the phase that follows transitional phase called Catagen. Your hairs undergoes the resting period. About 10-15 per cent of all of your hairs undergo this resting process at any given period of time. Telogen is the resting phase and accounts for 10-15% of all hairs. This phase will lasts for about a period of 100 days (for your scalp) and it will be more than 100 days for hairs present on your limbs, armpits, eyelashes, eyebrows etc. Your hair follicles are put at rest during this phase. Your hair development cycle gets completed. Your hair root will have a whitish dry, hardened solid substance. Every day you may be shedding about 75 to 100 Telogen hairs during this phase.
Reference Sources:
1) Hair follicle http://en.wikipedia.org/wiki/Hair_follicle
2) Hair http://en.wikipedia.org/wiki/Hair
3) Sebaceous gland http://en.wikipedia.org/wiki/Sebaceous_gland
Article published by R.Muthusamy, on May 15, 2009, Category in Scienceray
I Am Your Hair: Anatomy, Physiology and Growth http://scienceray.com/biology/human-biology/i-am-your-hair-anatomy-physiology-and-growth/2/
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