The Hair and How It Grows by Brittany McEwan

How a person styles up and takes care of the hair shows how important image is to him or her.  Whether a self-love like that is discreet or deliberate, no one can discount the hair’s role as a vital facet of appearance. Since ancient civilization, the hair is almost an ornament that speaks about identity and status in society. However, taking care of the hair is not just about fitting in. It is also about the desire to be beautiful and such desire does not easily die.

For this reason, losing one’s hair can really damage the self-esteem. Hair loss sadly affects a significant number of people from different races, ages, and sexes. To understand how hair loss happens, there is a need to understand the hair structure and how it normally grows.

Structure of the Hair

The hair consists of two separate structures: the root and the shaft. The hair root lies beneath the scalp’s surface while the hair shaft refers to the threadlike structure that springs up from skin.

            Figure 1: Hair Structure

            Photo Credit: transakpipeline.com

The Root

The hair follicle, dermal papilla, bulb, sebaceous glands, and arrector pili muscle compose the entire root structure. Stretching from the epidermis to the dermis is the follicle—the tubular part that bears the root and the bulb. At the base of the follicle is the dermal papilla that contains the nutrient-carrying blood and nerves.  The dermal papilla brings about and regulates hair growth. Attached to the hair follicle is the arrector pili muscle that causes the hair to stand erect due to fear or cold (the goose bumps). Surrounding the hair follicle are the sebaceous glands responsible for producing sebum.

The Shaft

The hair shaft is composed of three layers: medulla, cortex, and cuticle. The cuticle defends the hair shaft from damage. Each cuticle scale is attached to the cortex which is the fibrous protein layer composed of keratin and melanin responsible for giving color and elasticity to the hair. Lastly, the medulla is the innermost layer that contains round cells responsible for producing coarser and thicker hair.

How the Hair Grows

Hair growth starts when the hair follicles gather mature cells into a mass which both the sebaceous gland and arrector pili muscle thrust out to form the root sheath. The hair undergoes the following in the hair growth cycle: anagen stage (growth), catagen stage (transition), and telogen stage (resting). The entire hair growth cycle repeats every four to five years.

            Figure 2: Hair Growth Cycle

            Photo Credit: naturalcurlycrazyhair.blogspot.com

Anagen Phase

During the anagen phase, the keratinized cells at the roots multiply rapidly, that is at a faster rate than the rest of the cells in the body. Approximately 90 percent of the hair in the scalp is undergoing anagen phase which lasts from three to five years. Each month, the average growth of the hair is about one and a half inch.

Catagen Phase

During the catagen phase, at least 1 percent of the hair stops growing. This is because the hair follicle miniaturizes and comes off from the dermal papilla. This transition could last for one to two weeks.

Telogen Phase

In the last stage (telogen phase), approximately 10 percent of the hair comes off or sheds.

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