How is your hair made? Learn about hair structure and composition

How is your hair made? Learn about hair structure and composition
  • A large number of people are unaware of how important hair is for the body.
  • Even some individuals do not consider the hair a part of their body.
  • It is a commonly held misconception that hair is made up of dead cells that are not connected to the rest of the body.
  • The people who care about their hair will be able to take better care of it if they understand what it is made of.

People often see their hair as an expression of their personality and as an essential part of how they look. In addition, hair can offer some protection. For instance, it protects our scalp from sun radiation. Dust, dirt, and sweat stay out of our eyes thanks to our eyelashes and eyebrows. Germs and other foreign objects can also be kept out of our nose and ears by our hairs. Besides helping to regulate our body temperature, body hair also acts like a blanket to keep air that is warmed by the body close to us.



Hair Anatomy: A Brief Overview1,2,3

Hair is an outgrowth of the epidermis (outer layer) of the skin. It is composed of two distinct parts, namely the hair follicle and the hair shaft.

Hair Follicle

Hair is produced by the Hair Follicle. A hair follicle is defined as the sheath of cells and connective tissue that surrounds a hair root.

The hair follicles exist at the junction between the dermis and hypodermis. Hair bulbs are also known as these follicles. Blood is supplied to the hair by a small vessel that traverses the inside of the shaft, supplying it with many of what it needs to stay healthy, such as amino acids, mineral salts, and vitamins. Hair shafts are surrounded by glands, including the sebaceous gland, which produces sebum, which acts as a natural lubricant for the hair. In the scalp, pores remove sweat from the sweat glands.

An epidermis-embedded hair root is referred to as a hair follicle. The follicle plays an important role in hair growth. Hair can grow back if the hair follicle is still alive. It is impossible to grow hair if the follicle is dead.

It is estimated that humans have between 80,000 and 150,000 follicles on their scalp in an ideal scenario. In addition to continuous growth and rest cycles, hair follicles also have their own life cycle. Hair growth cycle can be divided into three phases: Anagen (growth phase), Catagen (transition phase), and Telogen (resting phase).

Hair strands can be in either growth or rest for varying periods of time depending on endocrine, vascular and neural factors. Moreover, where the hair strand is and factors such as age, gender and diet + lifestyle habits will play a role in this. As you grow older, the rate of hair growth and your hair density tend to decrease.

In ideal circumstances, 85-90% of our scalp hair is in the anagen phase, 1% in the catagen phase, and 10-15% in the telogen phase. It may take two to six years to complete the anagen phase, two to three weeks to complete the catagen phase, and three to six months to complete the telogen phase. As mentioned above, this is an approximation and varies from person to person.

A hair shaft is the strand of hair that is visible above your scalp. Among its components are the cortex, cuticle cells, and medulla. In a little more detail, let us explore the structure of hair.

Hair Shaft Structure1,2,4,5,6

Hair consists of keratin, a structural protein. This is the same protein found in hair, nails, and the top layer of the skin. Epithelial cells are protected from damage or stress by this substance. The keratin layer is fairly strong and resistant to wear and tear.

Three distinct layers can be seen in hair under a microscope. Among these layers are cuticle, cortex, and medulla.


Several elements make up a strand of hair7

The Cuticle

Hair is made up of layers, the outermost of which is called the cuticle. Protecting hair from the external environment is one of its most important functions.

It is composed of overlapping small scales. The cuticle gives hair its texture thanks to its tiny scales that overlap each other. The hair feels silky, soft, and glossy when the scales lie flat and nearly overlap. It will appear dull, break easily, and tangle if it is damaged or broken. Thus, it is responsible for maintaining the hair's texture.

In order to maintain the bounce and overall health of the hair, the cuticle needs regular nourishment.

The Cortex

Just under the cuticle, the cortex is the second or middle layer of the hair structure. Hair's strength and elasticity are coming from fiber-like cells. In the cortex layer, approximately 90 percent of hair's weight is contained. Your hair is naturally colored by melanin, which is found also in the cortex. White/grey hair indicates a loss of melanin.

The Medulla

In the hair structure, the medulla is the most inner and deepest layer. The keratin cells, which are very soft, are interspersed with spaces. All the vitamins and minerals required for hair growth are carried by the medulla to the outer layers of the hair, the cortex & cuticle.

Take A Look Inside Your Hair9

A scanning electron microscope image of the hair shaft shows (left), from the interior towards the exterior: medulla, cortex (which makes up 90% of the weight of the hair), and the protection envelope, or cuticle.7

Hair is much more complex than it appears on the surface. There are many layers, chemical bonds, and proteins in it.

Hair consists of approximately 45 % carbon, 28 % oxygen, 15 % nitrogen, 7 % hydrogen, and 5 % sulphur. The hair also contains 12-15% water as well as traces of calcium, cadmium, chromium, copper, zinc, iron, and silicon.

Keratin is a special type of protein that makes up the hair shaft. This is the same protein that forms the outermost layer of skin as well as the nails in humans. Keratin is an amino acid protein made up of the alpha helix, which is a polypeptide chain.

Alpha helix hair is held together by chemical bonds that give it shine, strength, bounce, and other special characteristics. The bonds are also responsible for making your hair kinky, curly, or straight! Let's look at this in more detail.

The Hydrogen Bond

As a result of this bond, we are able to style our hair as we like!

Hydrogen bonds are responsible for your hair's flexibility, tenacity and elasticity. The most flexible, the weakest, and the easiest to break or alter. The control system is electrolytic. We can manipulate the hair's shape temporarily with these products. As an example, rolling hair or straightening it. The styling of hair is done while it is wet due to the possibility of manipulating or breaking hydrogen bonds. Afterward, the hair is held in position until the bond dries, and as the bond dries, it takes the 'new' expected shape.

The Salt Bond

The strength and elasticity of hair are also caused by this electrolytically controlled ionic bond. In the cortex, they are abundant. Hair strength is about one third attributed to them. It is important to keep your hair's pH balanced in order to prevent salt bonds from forming. Salt bonds can be broken by changes in pH balance. Stabilizing and maintaining the balance will result in the bonds reforming and remaining.

The Cystine Bond

Cysteine bonds are also known as disulfide bonds or sulfur bonds and are probably the most important of all. Disulphide bonds are extremely strong and hold the hair fibres together.

The strongest bonds in hair give it its toughness. As well as protecting the hair from breakage, the disulphide bonds hold it together.

Extreme heat or chemicals cause the di-sulphide bonds to break. The breakage allows the keratin chains to move around slightly and assume a position that allows the hair to be shaped in the required style. This bond will also need to be broken in order to change hair colour. A hair colour uses chemicals that break this bond, allowing the color to penetrate and change your hair.

The Sugar Bond

Moisture is maintained in hair by sugar bonds. Nearly one fourth percent of your hair's weight is made up of water. It is crucial to stay hydrated, for this reason. By staying hydrated, the bonds will remain healthy and the hair will remain strong.

Your hair's composition pretty much defines its texture and style! Knowing how your hair works from the inside can provide you with the correct hair care regimen, products, and treatment. Furthermore, it helps you understand the importance of protein and mineral intake, as well as balancing the pH of your hair.

Hair foods that are high in proteins, vitamins, and minerals are essential for healthy hair. Healthy hair can be achieved through a balanced diet and adequate water intake.

It is highly recommended that you consult a professional trichologist who will guide you through the proper diet and lifestyle that is best for you as well as providing suitable treatments thus preventing hair loss concerns. The trichologist will examine your medical history, examine your hair and scalp physically, and diagnose through hair analysis using various methods and tech, such as the FCT, capillaroscopy, trichogram, hair pull test, and further investigate the hair shaft and growth window. Keeping your hair healthy and well-maintained is important through routine checkups.

Having hair loss is not a choice, but providing a permanent solution to it is a choice - your choice.

Please check out our blog posts on hair care, treatments, solutions, and such other interesting hair trivia for all things related to hair.

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  1. Erdoğan B. Anatomy and physiology of hair. Hair and Scalp Disorders. 2017 May 3;13.
  2. De Berker D, Higgins CA, Jahoda C, Christiano AM. Biology of hair and nails. Dermatology. 2012;3:1075-92.
  3. Paus R, Cotsarelis G. The biology of hair follicles. New England journal of medicine. 1999 Aug 12;341(7):491-7.
  4. Jones LN. The Hair Fiber Surface. InSkin, Hair, and Nails 2003 Sep 3 (pp. 279-310). CRC Press.
  5. Montagna W, Ellis RA, editors. The biology of hair growth. Elsevier; 2013 Sep 24.
  6. Wolfram LJ. Human hair: a unique physicochemical composite. Journal of the American Academy of Dermatology. 2003 Jun 1;48(6):S106-14.
  7. The Three Layers of Hair: Blog by Beauty Tomorrow, Image Credit: L’Oréal Research
  8. Gamez-Garcia M, Basilan J, Rocafort C, Mauras C, Chemicals BC. Challenges in formulating products for the ethnic hair care market.
  9. Dr. Sharmishtha Deshpande; What Your Hair Wants You To Know, Posted in


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