THE SCIENCE OF HAIR
HAIR STRUCTURE
Hair is comprised of kerantized cells that grow from an obiique tube in the skin called a hair follicle. Every hair is structured with columns of dead, keratinized epidermal cells that are bonded together by extracellular proteins. The hair shaft is the portion that projects itself above the surface of the skin and the hair root is the portion of the follicle, which penetrates deep into the skin (sometimes into the subcutaneous layers) and, ending in a dilation called the hair bulb. Interestingly, the only living cells of a hair are in and around the hair bulb itself. The hair bulb grows around a bud of vascular connective tissue, which provides the hair with its sole source of nutrition. Directly above the hair bulb is a region of active cells that is the hair’s growth center called the hair matrix. All the cells that are higher up are essentially dead.
One of the many reasons Neil Naturopathic encourages leaving our shampoos and conditioners on the hair and scalp for a couple of minutes is to allow the powerful nutrients to be absorbed deeply into the hair bulb and matrix itself, stimulating growth and repair to both the hair root, and shaft.
A hair has three layers that are called from outside in: the cuticle; the cortex, and the medulla. The cuticle is formed in multiple layers of very thin, scaly cells of hard keratin that overlap like roof shingles, except with the hair the free edges face upwards. Under a microscope a newly washed hair appears as an upside down Christmas tree. The cortex constitutes most of the bulk of the hair. It consists of elongated hard keratinized cells that appear in flattened cuboidal cross sections and give hair it’s stiffness. The medulla is a core of loosely arranged cells and air spaces. It is most pronounced in the thicker hairs of the eyebrows, but narrower in hairs of medium thickness. Interestingly it is mostly absent from the thinnest hairs of the scalp and elsewhere.
The hair follicle is a diagonal tube that contains the hair root. Associated with the hair follicle are nerve and muscle fibers. The nerve fibers, called hair receptors, entwine each follicle and respond to movements. Each hair also has a piloerector muscle which responds to both internal and external stimuli such as cold, touch or fear. When this happens the sympathetic nervous system stimulates the piloerector muscle fiber to contract and react.
Hair growth involves a specialized keratinization process. The hair root anchors the hair into the skin. The root starts at the hair bulb and extends to the point where the internal organization of the hair is complete, which is about halfway to the skin surface. The hair shaft then extends from this halfway point to the skin surface and then beyond. A hair in the scalp grows for 2 to 5 years at a rate around 0.33mm daily (1/64 inch). Hair growth rate and the time of the hair growth cycle account for differences in hair length. Every hair goes through a hair cycle that consists of three developmental stages: Anagen; catagen; and telogen. At any given time, about 90% of our scalp follicles are in the anagen stage where stem cells from the “bulge” in the follicle multiply, travel downward and transform into hair cells, which synthesize keratin. The new hair grows up the follicle, often alongside an old club hair left from a previous cycle.
In the catagen stage, the hair matrix stops, the sheath cells below the bulge die, and the follicle then shrinks. The hair keratinizes into a hard club and the hair (club hair) loses its anchorage and can be easily pulled out by brushing the hair. In the telogen stage, the hair goes into a resting period. A club hair may fall out during catagen or telogen phase or it can be pushed out by new hair in the next anagen phase.
We lose approximately 50 to 100 scalp hairs daily. In a young adult, follicles usually spend 6 to 8 years in the anagen stage, 2 to 3 weeks in the catagen stage, and 1 to 3 months in the telogen stage. In general, the hair grows fastest from adolescence until we are in our 40’s. After that an increasing percentage of follicles move from the growing anagen stage to the catagen and telogen phase. Hair follicles also begin to shrink and produce wispy vellus hairs rather than the thicker terminal hairs. Genetic hair loss, both thinning and balding, is called alopecia and to some degree occurs in both sexes though in males it is often a dominant gene as opposed to women who have the recessive gene. While hair thinning and loss can simply be a matter of aging, it is often worsened by disease, poor nutrition, and emotional stress. A condition called telogen felluvium that causes both mild and severe hair loss is often brought on by radiation, chemotherapy or even anesthesia. Also, because the hair follicle grows underneath the subaceous glands, that produce protective natural oils, both the hardening of those oils along with dirt and scurf as well as the elimination of those oils by harsh chemicals in commercial shampoos can also cause thinning and hair loss.
Neil Naturopathic products with their gentle plant based surfactants, and nutritional botanical oils and herbs work to allow the extension and promotion of the anagen stage of growth. Our shampoos work to remove excess oils including the hardened oils that can cause hair loss while also balancing new production of subaceous oils for the hair and scalp. Further, while we cannot change our genetic make-up we can offset its influences, by counteracting the effects of its expression. For example Rosemary oil, which is in both of our shampoos, our Restorative conditioner and our Elixir oil, contains Rosemary oil which has proven in many studies to be more effective than Minoxidil in counteracting the genetic effect of excess DHT in causing hair loss. Our Hair Tonic Tea with its 11 herbs, roots and flowers, in addition to our shampoos, conditioners and hair oils, has a nutritional profile, which stimulates hair growth and mitigates poor scalp health that often results in severe conditions of dandruff, eczema and psoriasis that can cause hair to move from the anagen phase to catagen and telogen.
