You may be familiar with your hair, what shampoos and conditioners you should use and your favorite type of styling products, but do you really even know what makes up hair? While each strand of hair is a rather simple structure, the makeup of hair is interesting and complex.
Each strand of hair has three layers. These are the cuticle, cortex and medulla. The cuticle is the outer layer made from overlapping keratin scales. Keratin is a strong protein, and these scales act as shingles on a home, protecting the inside from the elements. The cuticle is also covered with a molecularly small lipid layer which protects the hair from water.
The middle layer of each strand is called the cortex. The cortex is the primary source for structural support and water uptake. Approximately 91% of your hair is made from protein in the form of long chains of amino acids, and these chains are found within the cortex. This is also the area of each strand of hair that contains melanin, the pigment that affects hair color. The amount of melanin in each cortex is determined by genetics, and as you grow older, the melanin concentration depletes, causing your hair to turn gray and white.
The medulla is the core of a strand. This innermost region of the hair is not found in all hair types. For example, very thin hair or very light hair generally does not contain a medulla, but it is almost always found in very coarse hair. This means that some people may have strands of hair that only contain two layers, because the essential aspects to healthy hair growth and life are within the cuticle and cortex.
Each shaft of hair that you see extends below your scalp into the hair follicle. The part of the hair that is within the follicle is the hair root. New cells are formed and nutrients are received at the hair bulb, which is the round end of the hair root at the base of the follicle. These new cells mature through a process known as keratinization, which is where the protein hardens, and the new cells push the older cells up and out of the follicle, causing your hair to grow.
The shape of each strand of hair is determined by the shape of the hair follicle, which you can learn about in the “Not all hair is created equal” blog. Regardless, each hair strand consists of the same proteins and nutrients. Now that you know a little about how your hair grows and its makeup, you might can more easily understand why your favorite hair care products work for you. Make sure to discuss with your stylist any question you might have regarding keeping your hair healthy and yourself happy.