Science

The Anatomy of Human Hair

The Anatomy of Human Hair

The Science of the Surface: The Cuticle

The cuticle is the outer protective covering that covers the cortex of each human hair strand and is responsible for the lustre and texture of human hair. The normal cuticle is smooth, allowing light reflection and limiting friction between the hair shafts. It’s made up of six to eight layers of flattened overlapping cells and covered by an invisible, water-resistant lipid layer, which acts as a natural conditioner. Scientists call this layer the F-layer. This fatty acid layer is what naturally gives human hair its smooth and silky feel. Chemical processes such as coloring perming and relaxing strip the cuticle of the F-layer, which leads to what is generally referred to as “chemically-damaged” hair. Fortunately, Pantene scientists are experts in how to address the F-layer conundrum. Advanced Pantene Pro-V color shampoos, conditioners, and treatments are specially formulated for color treated and/or damaged hair and can restore a great deal of human hair’s natural softness, lustre and manageability.

Other common culprits that can ruffle the feathers of a healthy cuticle include excessive heat from blow dryers and flat irons as well as combing and brushing. Limit your hair’s exposure to heat by letting your hair air-dry until slightly damp, then use heat to set your hairstyle as it transitions from just damp to dry. When blowing your hair dry, hold the dryer three to six inches away from your hair rather than right up against it. Use a wide-toothed comb, especially when combing wet hair, and try to minimize brushing and combing in general. (Don’t believe the 100-brushstrokes-a-night-for-healthy-hair myth!)In addition to all these preventative measures, using the right shampoo and conditioner to protect and seal the cuticle can help it get back to its naturally smooth state, where it can reflect light and shine!

Heart of the Matter: The Cortex

Talk about a hard-working heart! The cortex is responsible for just about all of the defining properties of human hair, including strength, elasticity, shape, moisture content and color! Weight-for-weight, the cortex is stronger than steel and can be stretched to almost 30% without significant breakage. But just like the cuticle, the cortex can be damaged, too (by all the same villains - turn down the temperature on those flat irons, ladies!). When this happens, the cortex loses its ability to retain moisture, thus leading to dry hair. Keeping hair moisturized with the right products is key to getting and keeping that supple, silky texture we all love.

The Mystery Medulla

There’s another part of human hair structures that has no discernible function, and that’s the soft central core found in some human hair called the medulla. It is found in most mammals, but not in all humans. When it does occur in humans, it’s most often found in gray hair strands.

All About Color

Have you ever wondered what gives us all our unique hair color? The answer is melanin, which is a pigment we also have in our skin. Melanin is manufactured deep within the follicle and distributed throughout the hair shaft. But there are two distinct sub-types of melanin, which better illuminates why there are so many variations of human hair color. The first is Eumelanin, which accounts for black and dark brown hair colors. The second is Phaeomelanin, which is what red hair has almost exclusively. It is the mixture of these two pigments in varying concentrations that creates blonde to light brown hair and everything in between.

Grey Matters

Genetics play the most important role in determining when you’ll see those first grey hairs. But what causes grey human hair? As time passes, the cells that produce your unique color of melanin (pigment) produce less and less of it. In other words, pigment cell renewal fizzles out. And by age 50, 50% of people have 50% grey hair! Fortunately there is a wide array of outstanding coloring products on the market today, so you don’t have to stay gray grey unless you decide that you want to!