The Truth About Hair Growth

The Truth About Hair Growth.
Nothing in​ life is​ as​ simple as​ it​ seems,​ so it​ should come as​ no surprise that the​ strand of​ hair that you​ found on​ your brush this morning is​ an​ amazingly complex part of​ your body .​
Hair begins appearing on​ the​ human body while it​ is​ still in​ the​ womb .​
By the​ time a​ developing fetus reaches 22 weeks old,​ there are already 5 million follicles on​ the​ body .​
Interestingly enough,​ that is​ all of​ the​ follicles that will ever develop regardless of​ how long we​ live .​
None will ever be added.
Hair Anatomy
Hair consists of​ a​ follicle,​ which is​ embedded in​ the​ skin,​ and the​ shaft of​ hair which appears on​ our body .​
The follicle itself consists of​ multiple layers with each layer having a​ specific function .​
The papilla lies at​ the​ base of​ the​ follicle .​
Capillaries are connected to​ the​ papilla and they supply blood to​ the​ cells which surround the​ bottom part of​ the​ hair strand called the​ bulb.
Surrounding the​ follicle are two sheaths,​ inner and outer,​ which are designed to​ both protect the​ hair shaft from damage,​ and to​ help it​ grow out in​ the​ proper direction .​
The inner sheath runs next to​ the​ hair shaft and ends at​ the​ oil (sebaceous) gland .​
The outer sheath runs to​ the​ gland and ends at​ the​ erector pili muscle .​
This is​ the​ muscle that causes our hair to​ stand on​ end when it​ contracts.
The hair shaft is​ comprised of​ three layers of​ dead protein cells called keratin .​
The innermost layer,​ known as​ the​ medulla,​ is​ not always present in​ every hair shaft .​
The second layer,​ known as​ the​ cortex,​ provides the​ bulk of​ the​ hair shaft .​
The hair color is​ mostly determined by the​ pigmentation contained in​ this layer .​
The outermost layer is​ called the​ cuticle .​
It is​ comprised of​ a​ series of​ overlapping cells .​
The hair's luster and sheen comes from the​ cuticle.
How Hair Grows
Scalp hair grows at​ an​ average rate of​ six inches per year,​ or​ only .3-.4 mm per day .​
There are three distinct stages of​ hair growth.
- Catagen Phase
This transitional phase runs about two to​ three weeks .​
At any given time approximately 3% of​ your hair is​ in​ this phase .​
There is​ no hair growth during this period while the​ out portion of​ the​ hair root sheath shrinks and attaches itself to​ the​ root.
- Telogen Phase
This phase,​ known as​ the​ resting period is​ experienced by approximately 15% of​ your hair .​
Telogen lasts for​ around 100 days for​ scalp hair and significantly longer for​ other body hair.
- Anagen Phase
This phase defines a​ period of​ activity where the​ hair cells are dividing and new hair growth occurs .​
This phase can last for​ as​ long as​ two to​ six years .​
Shorter growth periods are indicative of​ people who have trouble growing their hair long.
Hair Growth Disorders
There are two hair growth disorders that affect humans .​
Hirsutism is​ a​ condition affecting mostly females .​
It is​ defined as​ a​ condition where excessive thick and dark hair growth is​ experienced in​ areas typically reserved for​ males .​
These areas include the​ face,​ chest and the​ areolae or​ area surrounding the​ nipple .​
Hypertrichosis is​ a​ condition which causes excessive hair growth in​ areas of​ the​ body where visible hair is​ not normally present .​
Both of​ these conditions are treatable.

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