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Hair 101: Get to know your hair's anatomy.
By: Dressy Tresses
The more you know about your hair, the better you'll be able to decide which style, length and color is right for you. Much of the frustration people seem to have with their hairstyle choice seems to stem from fighting with their hair to get it to perform in ways that are unnatural for its unique composition. At Dressy Tresses, we feel that you can avoid much of this frustration by understanding what makes your hair uniquely your own and then working with your hair in ways that complement its structure.
It all started before you were born.
Every hair has its own follicle, and you never grow more follicles during your life. In fact, your follicles were formed within 22 weeks after conception and at that time, you've got all the follicles you'll ever have - about 5 million of them. Interestingly, blondes have slightly more follicles than average and redheads have slightly less. Nearly one million follicles are on your head, but only about 100,000 comprise the follicles on your scalp. For the purposes of our discussion, we'll focus on the hairs on your scalp since they generate most of the attention in your life.
And now, the root of our discussion.
Each hair grows from a pocket in your skin called a follicle. The hair follicle looks like a sac that surrounds the root of your hair. At the very base of the follicle is the only living part of your hair - the bulb, which is attached to the dermal papilla. The dermal papilla is fed by tiny blood vessels and is very sensitive to your body's hormones. Chemicals, too, affect the papilla, such as medicine you may take, and even your diet. All these factors work together on the hair bulb, making it grow fast, slow or not at all. Interestingly, cells in the hair bulb divide every one to three days, which is faster than anywhere else in your body.
The genesis of color.
Within the dermal papilla are cells that determine the color of your hair. Known as melanocytes, they produce a pigment called melanin that is incorporated into the growing hair shaft. The type of melanin that your body produces is what determines the color of your hair. Eumelanin produces hair colored black to brown; and pheomelanin produces hair colored blonde to red.
Hair has layers, too.
Your hair is made of a protein called keratin - the same protein found in your fingernails - and is comprised of three layers: the outermost layer is called the cuticle. The cuticle contains none of the melanin your body produces, so it is transparent and serves to protect the inner layers of the hair shaft. The cuticle is formed by tightly packed scales in an overlapping pattern similar to shingles on the roof of a home. Most hair conditioning treatments attempt to affect the hair health of the hair cuticle.
The next layer in is called the cortex, and it comprises the bulk of your hair shaft. The color-producing melanin pigment is distributed throughout the cortex and is what gives your hair its characteristic color. The innermost layer of your hair shaft is the medulla, which may not extend above the surface of the skin in some people, but is comprised of large baggy cells.
Hair. It's a growing thing.
As the hair bulb grows and divides, it pushes the keratin up out of the follicle and continues doing so until it reaches its natural length. Healthy hair will grow between half an inch to an inch per month, depending upon your genetic make-up, hormonal activity, chemical interactions, diet, nutrition, vitamins and other factors, many of which are not known or fully understood. However, we do know that hair follows a well-established life cycle that has three distinct phases.
Your hair's life cycle.
The first phase of life for your hair follicle is the growing stage, called the anagen stage. This stage last three to five years, during which time the hair bulb continuously manufactures keratin, which it pushes upward and out the hair follicle. As we mentioned, during the growth stage, hair can grow between half an inch to an inch per month, and may grow faster when it's hot and slower when cold. The speed by which your hair grows also slows down as you get older. Approximately 90-percent of your follicles are in the anagen stage of life at any given time.
The second phase of life for your hair is also the shortest: the catagen stage, or transition phase. During this stage, your hair follicle is undergoing chemical and structural changes that halt the production of keratin and stop your hair from growing. This phase lasts only two to three weeks and prepares the hair follicle for its final stage of life: the telogen phase.
The telogen phase is the final stage of life for your hair shaft and can last up to three months. During this time, the hair just sits in the follicle, waiting for its turn to fall out. The average person sheds 100 hairs per day. After the hair falls out, the hair follicle starts over and begins to replace the lost hair bulb and shaft with new hair - unless the follicle is being affected by baldness or disease, in which case the follicle does not replace the hair.
Hair has a shape of its own.
Just like people and body shapes, your hair has its own unique shape, too. Hair shape is determined by genetics and the shape of your hair's shaft determines the amount of natural curl your hair will have.
If you were to take one of your hairs, cut it cleanly and look at a cross section of the hair shaft under a microscope, you would be able to see whether the shaft was circular in shape, or elliptical. The more circular your hair shaft appears, the more straight your hair will naturally be; likewise, the more elliptical, the more your hair will be naturally curly or kinky.
Shape also plays a critical role in determining how shiny your hair will be. But before we get to how shape affects the shininess of your hair, we need to discuss the role of your follicle's sebaceous glands.
The sebaceous glands are located inside the hair follicle and they secrete oil that coats your hair shaft. The oil is called sebum, and it's your hair's natural conditioner. Sebum keeps your hair shiny, keeps the outermost cuticle of the hair shaft in good health, and seals it, making it waterproof.
Your body produces more sebum during puberty and then begins to slowly produce less over the course of your life. For some reason, sebum production slows down faster in women than with men.
In any case, the shape of your hair shaft affects the way the sebum coats your hair. The more straight your hair is, the easier the sebum flows down the hair shaft. Accordingly, people with straight hair tend to have shinier hair.
And that concludes Hair 101: Everything you wanted to know about your hair but were afraid to ask. Future articles at Dressy Tresses will discuss how you can use this knowledge to work with your hair's natural strengths to find the right hair style for your hair's structure.
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