Hair has two seperate structures: the hair shaft (the part we see above the skin) and the follicle (the part that is below the surface of the skin). The hair shaft is composed of strong structural protein called keratin. This is the same protein that makes up the nails and the outer layer of the skin.
Below the surface of the skin is the hair "root" or hair follicle comprised of several structures: dermal papilla, hair bulb, hair shaft, sebaceous gland, and a tiny muscle.
The dermal papilla is made up of connective tissue and a capillary loop creating the place where hair production originates and where hair receives its nutrients. The hair bulb is located above and around the papilla; it contains a collection of epithelial cells interspersed with cells producing a pigment called melanin. Generally, if more melanin is present, the color of the hair is darker; if less melanin is present, the hair is lighter. This part is also called the hair matrix because it is responsible for the manufacture of the hair. The hair matrix is one of the fastest-growing cell populations in the human body, which is why some forms of chemotherapy or radiotherapy that kill dividing cells may lead to temporary hair loss.
Each strand of hair (hair shaft or hair fiber) contains three layers: medulla, cortex, and cuticle. The medulla is the innermost layer found in large and thick hair. The cortex is the middle layer, which provides strength as well as imparts color and texture to the hair. The cuticle is the outermost layer made up of tightly packed scales that form an overlapping structure similar to the roof shingles and function as a protective coat over the cortex. Most hair-conditioning products attempt to affect the cuticle by making these scales lie flat, thereby imparting a silky feel to the hair. Attached to the hair follicle is a sebaceous gland, a small sebum-producing gland found everywhere except on the palms, lips, and soles of the feet. The purpose of the sebum, an oily and waxy matter, is to lubricate the skin and hair keeping them waterproof and protected from dehydration. More sebum is produced after puberty.
The sebum production decreases throughout life with greater reduction in women than in men. Also attached to the hair follicle is a tiny bundle of muscle fibers called the arrector pili. When this muscle contracts, it causes the hair to stand up resulting in a phenomenon commonly known as goose bumps. The bulge is located at the insertion point of the arrector pili muscle. It houses several types of stem cells, which supply the entire hair follicle with new cells and take part in healing the epidermis after a wound. This portion of the hair follicle is vital for transplanted hair to regenerate, especially if it gets damaged during the hair-transplantation process.
Medical Suite Building,
Arwyp Hospital, 22 Pine Avenue,
Kempton Park, Johannesburg.
Behind La Coline Commercial Centre,
Candos (close to hospital) Quatre Bornes