Here at Deva, we’re all about the science behind hair.
You may be asking, “why should I care about the structure of my hair?” Well, knowing the ins and outs of your strands can lead to healthier curls and who doesn’t want that? Let’s get into it.
Your hair strands are made up of a mixture of protein, moisture, lipids, pigments, minerals, and carbohydrates. Proteins such as keratin help keep the hair strand strong and compact, while lipids such as sebum coat the hair to keep it moisturized.
Each strand of hair is made up of 3 parts; the cortex, medulla, and cuticle. The cuticle (or the outer layer) works as a protectant for the hair. It is also transparent in color. The cortex (or the second layer) contains the natural melanin in your hair. This means that you have your cortex to thank for the natural color of your hair! The cortex also contains moisture. Lastly, the medulla (or the core) is actually quite interesting. We’re not totally sure what function of the medulla is and some people actually don’t have it at all!
Hair Growth Phases
When we’re born, we have around 5 million hair follicles. This is the largest number of hair follicles we’ll ever have as we don’t form new hair follicles as we age. On average, hair grows about 6 inches per year so to all of our curlfriends asking for hair growth tips, patience is always key!
Now we’re really going to get into it. Hair has four growth phases: anagen, catagen, telogen, and miniaturization. The normal growth cycle of a single strand of hair can last anywhere from two to six years.
Anagen phase is the growth phase, which lasts two to five years and includes 90% of hair.
Catagen phase is a three-week regression phase in which hair growth stops.
Telogen phase is the three-to five-month rest phase in the hair growth cycle.
Miniaturization occurs at the end of the telogen phase when the hairs fall out, and instead of being as thick as previous hairs, they are being replaced by thinner, finer versions of themselves.
Although we’d love for our hair to stay thick and healthy throughout the entirety of our lives, it’s normal for growth to slow down and density to thin out as we age.
Big word, we know. Ellipticity refers to the degree of deviation from the circle or sphere shape hair strands have, which is how curls come in! When ellipticity increases, so does the degree of curl. People with a high degree of ellipticity are prone to more fragile hair strands. Essentially, the higher the ellipticity, the tighter the curl.
Okay okay, we’re done boring you with sciency stuff…for now!
Have any questions about the structure of hair? Leave ‘em down below!