Hair Biology, Skin Biology, Hair Shaft

Hair is made up of a certain type of protein known as keratin. As with any part of our body, hair has several parts that make up its biology. One strand of hair consists of a hair shaft the part that is visible and grows above the skin, and the follicle the part from which the root of the hair grows and is located below the epidermis. The hair bulb, which is a small but important part of the hair, produces the hair's color pigment and is located at the end of the follicle.

Hair biology: the structure and functions of the different parts of hair

Hair follicle

The hair follicle is made up of different layers with different functions. The papilla, located at the base of the follicle, contains capillaries that feed the cells. The bulb, the hair's living part, is located at the lower end of the follicle. The bulb is the only part of the hair that is fed by the capillaries.

Two sheaths surround the hair follicle. The sheaths protect the growing hair shaft. The inner sheath covers the hair shaft and ends just below the opening of the oil glands. The outer sheath covers the hair shaft and continues up to the oil glands. The erector pili, a muscle that attaches the gland to the outer sheath, when contracted makes the hair on your skin stand up producing goose bumps.

Hair shaft

Hair shafts are made up of dead protein called keratin. This hard protein comes in three layers. These layers are the medulla or inner layer, the cortex, and the cuticle or outer layer. The hair shaft is made up mostly of the cortex. The cuticle is made up of scales similar in structure to roof shingles.

Skin and Hair

The part of hair we see growing on our skin and scalp is the hair shaft. The follicle and the root of the hair are located just below the skin. One of the largest organs in the human body; the skin is often overlooked in terms of an individuals health and welfare. The skin has a wide range of functions, some of these functions are:

Provide a flexible support and protection for the bodys underlying organs and tissues
Sweat glands in the skin provide a way for removing waste materials from the body
Provide a way to feel sensations such as temperature, pain and pressure
Protection from ultra violet light
The skin also acts together with hair in preventing heat loss. Skin and hair maintain the bodys temperature through trapping air, providing an insulating layer for the skin.

The importance of hair and skin has gone beyond the typical biological functions and purposes. Aside from the health related functions of hair and skin, both parts of the body are also big considerations when it comes to cosmetics. Hair and skin have become major parts in an individual's declaration of uniqueness and individualism through different hair styles, colors and even skin piercings.