Human hair, despite its simple structure, can be considered an important part of our body. The hair that you see on your skin is not required for normal functioning of your body. However, its mere existence can affect one’s self-confidence and mental mood and therefore affects people’s quality of life. In other words, it plays a crucial role in social behaviour of a person. You have seen a lot of people that are spending lots of money on the maintenance and services. Services such as haircare products, stylists and or transplant surgeries.
It is considered as one of the tissues that grows continuously until the end of life. So, it requires delicate maintenance. The rate of its growth varies in different people and is about one-half of an inch every month. Also, the colour that you see, is because of the pigment cells that release melanin and gives the colour to the tissue. Once someone grows old, these pigment cells die out, and as a result, the tissue turns grey.
The tissue is mostly made up of keratin, a protein that is insoluble in water, thus provides impermeability and protection for your hair. The structure can be divided into three specific parts known as: medulla, cuticle and cortex. Medulla is the innermost layer that is made up of some soft and oily substance. The outer layer, called cuticle, is a protective layer that plays a crucial role in hair growth, since it contains the nourishing part. In addition to those, cortex contains long chains of keratin which is the main component of the tissue. These chains are known to provide some properties to the hair, such as elasticity, suppleness as well as resistance.
As I said earlier, medulla is located right at the centre of the hair shaft. But for some unknown reasons it is not present in all hair types, especially in people that have thin or light blond hair. But since medulla contains structural proteins, its existence in thicker hair types and also in darker ones provides support for the structure of the tissue. In other words, it is said that the medulla is the supporting structure. So, you may ask what is the actual purpose of the medulla? Or what does it do? This is a good question to ask, since there are various answers to it. Although some scientists are still uncertain about its exact role. But on the other side, some people say that in addition of having some structural roles, it is also important in keeping the moisture.
So, they say the hair strand is like a tree, the moisture is located at the centre (medulla) which is being protected by a tough layer around it (cuticle). Thus, the moisture in the tissue is probably kept in the medulla at the centre of the shaft. In addition, the cuticle which is the outer layer is responsible for many things, but one of its crucial functions is to allow the moisture in and out of the medulla.
Since the medulla (we may call it the core of the hair) is probably important in order to maintain the structure of the shaft. Therefore, the cuticle is responsible to protect it from various environmental damages, such as chemicals and toxins, sunlight, wind and also air pollution. Since if the medulla is damaged, it will be unable to maintain its moisture and will suffer from dehydration. As a result of damage to medulla, the tissue will be more prone to other damages due to being dry.
The next part of the hair shaft which is considerably important is cuticle. The cuticle layer is the outermost and the protective layer of the hair strand which is made up of dead cells. These dead cells overlap one another and, in that way, strengthen and protect the tissue from external damages. Therefore, these cells form a structure that is very much like fish scales. When it comes to hair growth, we could say that cuticle is probably the most important factor that needs careful consideration. Because healthy cuticles affect the appearance of your hair massively and if you don’t have healthy cuticle in your strands, then it will be very difficult to have long beautiful looking hair.
Cuticle layer works like a gate for your hair. So the dead cells that are overlapping and form the scales can rise and let the chemicals and ingredients to pass through the cuticle layer and enter the cortex layer. Although all cuticle layers are made up of dead cells, but they aren’t created the same and they can vary depending on the hair type. As an example, in straight hair type (type 1), the cuticle attaches to the cortex very tightly and the dead cells lay flat naturally. As a result, you often see more shine on type 1 and also they are able to stay moisturised for a longer period of time. On the other hand, in curly types, the scales in the cuticle layer are raised (they don’t lay flat), therefore, they are less shinny and more prone to frizz.
The cortex is the thickest layer of the hair strand and is located between the medulla and cuticle layers. Although cuticle is the outer layer, but it is not involved in the colour of your hair. However, it is the melanin that gives the hair its colour and is found in the cortex part of the hair strand. The cortex layer comprises nearly 90% of total weight of your hair strand and is the region that gives your hair its physical and mechanical properties.
In total there are four basic colours in the hair which are the result of pigments, these colours are yellow, red, brown and black. Furthermore, these colours or pigments are usually mixed and comes in various proportions, therefore, you see a variety of hair colours, such as brown, reddish and blond. But the cells that are responsible for producing melanin can age over time, and therefore they stop producing melanin pigments. As a result of this, your hair turns grey or white once you grow older. In addition, a lot of proteins are also present in the cortex layer. These proteins describe the shape of your hair. In other words, which hair type you have (straight or curly) depends on these proteins.