Hair | Biology, Types & Growth Cycles
When considering proper hair care, it is helpful to understand hair types and fundamental functions of the hair as it progresses through its growth cycle as well as the role of hair products. To respond to hair loss or thinning hair, a hair loss analysis may be necessary to identify causes of hair problems. Understanding the hair’s cycle and biology helps in developing solutions for healthy growing hair.
Human hair falls into three basic groupings: lanugo, vellus, and terminal hairs. The first hairs to appear in the follicle are lanugo which are fine and without the medulla (comprised of loosely, hardened cells at the center of the hair – not uncommon for the center to not be present, especially in finer hairs). They have little or no melanin (color) and are generally colorless. Lanugo hairs vary in length, but are short and rarely exceed several centimeters. They are formed before birth.
Vellus hairs resemble lanugo hairs, rarely exceeding several centimeters and can best be characterized as the smallest, light facial hairs.
The largest of the hairs are terminal hairs and are the most common and noticeable of hair types. Terminal hairs often lack a medulla, and terminal hairs on the scalp have been known to exceed 39 inches in length. Terminal body hairs rarely exceed 1 inch.
Patterns of hair on the body are directly related to the three types of hairs. Lanugo hairs are replaced by vellus hairs as we mature and grow except for hairs on the brows, scalp and face where they are replaced by terminal hairs which are coarse and grow longer. Loss of terminal hairs can begin at age 40. Hair patterns are dynamic and are constantly changing.
Follicles are distributed over the entire surface of the skin except for palms and soles. Hairs develop out of the follicle at an angle to the skin’s surface, and regardless of the hair’s size or length, all hairs are “born” in the hair bulb, a mass of cells at the base of the follicle.
All hair progresses through a growth cycle made up of three stages: The Anagen is the growth stage and generally lasts up to about four years. This stage is followed by the Catagen phase, is transitional and can last up to three months. The final, or resting stage, is the Telogen stage during which a new hair bulb is developed. At any point, hairs – in particular those of the scalp - can be moving through any of these three cycles.
Regarding hair loss, thinning or slow growing hair, it is necessary to identify stages of the growth cycle along with understanding which environmental or physiological factors may be influencing hair growth. Hair is susceptible to hormonal changes, excessive sebum (oil) production, stress, nutrition, medication, pregnancy or childbirth, and to environmental factors such as product build-up, chemical treatments, sun and photo-damage, and styling.
Much hair loss is temporary and can be addressed by hair products formulated to increase blood circulation, block DHT enzymes, or to deep clean the scalp. Life-style changes – reduced stress, improved nutrition, and adequate exercise and water consumption – can have a significant effect on hair loss and thinning.
Many of these slow growing issues can be addressed with a hair growth shampoo with Trichogen. Additionally, natural products have been shown to work as effectively as synthetics for maintaining and encouraging normalized biology of the cuticle, root and shaft. An herb shampoo that either helps growth, body or that acts to deep clean and clarify can help avoid stripping natural nutrients and oils necessary for follicle pore and scalp health.
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