The Biology Behind Hair Growth

By:Andrea Strachan

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.

Digg del.icio.us Blink Stumble Spurl Reddit Netscape Furl

Article keywords: hair, growth, removal, permanent, pubic, shaving, head

Article Source: http://www.articles2k.com

Andrea Strachan has been in the beauty business for 25 Years. For more information about the biology of hair growth , visit Permanent Hair Removal Tips . For info about the latest Sedu hair styles click here.

Top Beauty Articles
1). TCA Skin Peel: Cost-Effective Way to Treat Acne By : David Maillie TCA peels have been found to be one of the most cost effective treatments for acne that exist. They are used by doctors, plastic surgeons, and medi-spas everywhere and are now directly available to the consumer.
2). Cosmetic Dentistry Fixes Are Big Business for Dentists By : Roger Campbell Blame it on Hollywood for the dramatic increase in cosmetic dentistry. Thanks to those stars with the dazzling white teeth and photo-op grins, more Americans are choosing to brighten up their smiles with veneers, teeth whitening and oral laser surgery. In fact, according to the American Dental Association, more than $35 billion a year is spent on cosmetic dentistry.
3). Swallow To Glow - A Holistic Approach To Skin Health By : Debra The skin is the largest organ in the body. It defends against disease and infection, regulates temperature and even aids in vitamin production. Keeping skin healthy is crucial for beauty and general health, even if most of us are interested in knowing how to keep skin looking healthy, rather than really keeping it healthy. The best way to keep skin looking healthy � young, fair, radiant, supple, soft and wrinkle free � is to keep out of the sun.
4). Varicose veins can cause bad circulation. By : Hege Crowton What are varicose veins? You can get this all over your body but in most cases you can clearly see it on your legs. Little blue and red lines that starts to appear and �grow� on your legs and in other cases the blood vessel becomes swollen and seems as if it will explode.
5). Cosmetic Dentistry - For That Brilliant Smile By : Barney Garcia Cosmetic dentistry offers options ranging from polishing, bleaching, covering techniques, bonding, implanting and orthodontia for complete mouth over, to give you the perfect smile. Recent medical advances have reduced the pain and trauma associated with dental work. An experienced dentist can help you to get that beautiful, brilliant and dazzling smile you always aspired for.
6). Woman's Feet Gain National Attention By : Roger Campbell Few people can say that they are famous for their feet. One woman's feet, however, are getting national attention. Carmina Swofford, whose feet were recently named "the prettiest feet in Texas," will appear in national advertisements showcasing the new look of Pretty Feet & Hands, B.F. Ascher's popular exfoliant for dry skin. "I have always been told that I have pretty feet," said Swofford of Austin, Texas.
7). Anti Aging Skin Care Products By : Stephen Todd When a person wishes to purchase an anti aging skin care product, they will most likely wind up choosing a cream because it is one of the most popular forms of anti aging skin care products on the market.
8). 10 Tips to Maintain Health and Beauty By : paul wilson1 Beauty, health, and nutrition are all integrated. If you eat a balanced diet you will be able to maintain your physique and glowing beauty externally and good health internally. A balanced diet is one that provides all the nutrients you need, the right amount of proteins, carbohydrates, and fat. To achieve goals you need to ensure a good balance in your diet, introduce variety into your meals, and practice moderation.
9). Natural Weight Loss Tips\|Lose Weight Program By : Chris Chew How to lose weight naturally and keep unwanted weight off forever.
10). Teen Stretch Marks By : Nicky Pilkington The teen years can be a very difficult period. Your body undergoes some significant hormonal changes that can wreak havoc on your daily life and consequently your level of confidence. Many teenagers experience sudden growth spurts while these hormonal changes are taking place.

New Beauty Articles
1). Anti Aging Skin Care: Tips on Having Skin Blessed with Eternal Beauty By : Lee Dobbins Tips on how to keep your skin looking young and vibrant well into your golden years.
2). What Is The Link Between Anti-Aging And Ethnicity? By : Louise Forrest It is very true that Caucasians are more affected by sun damage (photo aging) and the associated visible signs of aging more than many other ethnic groups, but the number of anti-aging dermatological procedures being performed on people with diverse ethnic backgrounds has been on the rise in the past few years.
3). Tips on Buying Contact Lenses Online By : Mayoor Patel Do you have an urgent need to buy contact lenses from an online store instead of a traditional one? Or have you found the design you have been looking for all along in a certain website? Whichever the case, you should be properly informed when buying contact lenses online.
4). Facts About Contact Lens Saline Solution By : Mayoor Patel When it comes to contact lenses, the saline solution is as essential as the lens it self.
5). How To Control Psoriasis And Your Emotions By : Louise Forrest An important aspect of psoriasis is the emotional impact it has on its sufferers. Depression during outbreaks and happiness during remissions are normal, but affect both you and those around you.
6). How To Slow Down The Ageing Process By : Louise Forrest Your skin ages through both inner and outer aging factors. Inner factors include overall health, nutrition, water content, hormone balance, genetics, and toxins. Outer factors are mainly sun and pollution.
7). Hair Laser NYC Removal By : Harry Rockwell Hair laser nyc removal is a relatively comfortable and safe method of getting rid of unwanted body hair. Whether it is your neck, chin, legs, back or any other part of the body you can resort to this process without any second thoughts. Both males and females have undergone this treatment with good results.
8). Hair Removal Methods, Remove Facial Hair By : John Lim Top Hair Removal Methods That Will Result In Smooth, Silky Skin. Discover How You Can Remove Facial Hair Effectively Today!
9). Bring Out The Beauty Of Your Face With The Correct Use Of Blush By : Gregg Hall Some people are blessed with natural blushing color and high cheekbones. For the rest of us we need a little help to achieve the same healthy glow. When you were a child you had a sweet pink tint to your cheeks, to keep that youthful tint most women use blush.
10). Laser Hair Removal Facts By : Aaron Vaughn When performed by a qualified professional, laser hair removal is a great way to remove unwanted hair.

� 2006 articles2k.com - Privacy Policy