Everything 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. A human’s hair growth starts inside the womb as a developing fetus. After 22 weeks of developing, a fetus has about 5 000 000 follicles on its body. Interestingly enough, that is all of the follicles that will ever develop regardless of how long we live.

The Anatomy of Hair

Hair consists of a follicle, which is embedded in the skin, and the shaft of hair which appears on our body. A follicle consists of various layers, each with its own specific function. The papilla can be found in the base of each 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. Inner sheaths run next to the hair shaft, ending in the oil gland (sebaceous). The outer sheath also runs into the glands but they end in 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 medulla is the innermost layer, but is not always present in every hair shaft. The Cortex is the second layer and it provides the bulk of the hair shaft. Hair pigmentation can be found in the cortex, determining the color of our hair. The cuticle is the outermost layer of the hair shaft.It is comprised of a series of overlapping cells. The cuticle also gives luster and sheen to the hair.

The way hair grow

Scalp hair grows at an average rate of only 0.3mm to 0.4mm per day, adding to a mere six inches per year.

There are three distinct stages of hair growth.

Catagen Phase

This phase is the transitional phase and it runs about two or three weeks. At any given time you will find approximately 3% of your hair 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. The Telogen phase for scalp hair lasts for around 100 days and significantly longer for any other hair on your body.

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. People who have trouble growing their hair long usually experience shorter growth periods.

Hair Growth Disorders

Humans are mostly affected by two hair growth disorders. Hirsutism is the most common condition that affects mostly females. It can be defined as a condition with excessive dark and thick hair growth (in areas typically reserved for males) is experienced by a female. The areas may include the face, chest, areolae or the area around the nipple. Hypertrichosis is the other common condition, causing excessive hair growth in areas of the body where visible hair is not normally present. Both of these conditions are treatable.