Hair Anatomy
"To Care for Hair, You Must First Understand It."
Every individual hair appears quite basic; however, it is a fascinating biological organism, which has been meticulously developed. As hairdressers, our knowledge of the hair anatomy should be our foundation for making decisions about hair care, scalp treatments, hair extensions, wigs, and hair transplant services.
The stylist, who knows the hair anatomy, is not just styling hair; he or she understands hair behavior, reasons for hair damage, and ways to protect it.
First of all, let us discuss the anatomy of one hair strand.
Hair: Alive at the Root and Dead at the Shaft. One of the biggest mistakes is a perception that the whole hair strand is alive.
Actually: Hair root, which is under the skin in the hair follicle, is alive and produces new hair cells. The visible part of the hair called the hair shaft consists of dead cells covered with keratin. That is why you do not feel pain when cutting off your hair, while pulling does cause the pain. The pain is caused by the living follicle, which is connected to the nerves.
There are two main parts of hair:
1. Hair Root
The hair root is that part of hair that lies beneath the scalp. The hair root is contained in the hair follicle, which generates new hair. The hair root gets nourishment and oxygen from the small blood vessels present there, enabling the hair to grow continuously throughout its growth stage. If there is no healthy hair root, no healthy hair can ever be formed.
2. Hair Shaft
The hair shaft is that part of the hair that protrudes from the scalp. Though it is composed of dead cells, its state depends on how it has been treated. All our actions like shampooing, combing, dyeing, straightening, curling, putting on wigs or extensions affect the hair shaft.
Layers of the Hair Shaft - The three layers of each strand include:
1. Cuticle – The Protective Shield
Cuticle is the outer layer of the hair. It is composed of transparent and overlapping cells, just like roof tiles. Its main purposes are:
- Protecting the inner layers
- Retaining the moisture
- Giving shine
- Minimizing friction
- An intact cuticle results in smooth and shiny hair.
However, when exposed to too much heat or chemicals, it may lift up and cause the following problems: Frizz, Dryness, Splitting, Tangling, Breaking
2. Cortex – The Strength of the Hair
Cortex is the biggest part of the hair strand. It includes:
Keratin proteins
Pigments (melanin)
Moisture
Cortex is responsible for: Hair strength, Elasticity, Texture, Color
All chemical treatments of hair involve manipulating the cortex.
3. Medulla – The Heart
Medulla is the innermost layer of hair. It is quite interesting to note that all the strands do not have medulla. It usually becomes prominent in coarse hair whereas fine hair completely lacks this layer. Its exact function is yet to be understood but it is known to perform the function of insulation.
The Hair Follicle – The Hair Manufacturer
Under each strand lies the hair follicle. Imagine it to be the little factory responsible for manufacturing hair. Follicle contains everything necessary for hair growth such as:
- Hair bulb
- Dermal papilla
- Blood vessels
- Stem cells
- Oil gland
- Arrector pili muscle
Healthy follicles are the key to healthy hair.
Hair Bulb
The hair bulb lies at the bottom of the follicle and is where hair cells are produced. They multiply quickly, forcing older cells up. During this process, the older cells harden with keratin to form a hair shaft.
Dermal Papilla
Dermal papilla is a tiny structure that lies at the bottom of the hair bulb. It provides:
Oxygen, Nourishment, Hormones, Growth factors. Without the dermal papilla, hair growth cannot proceed.
Sebaceous Gland
Every hair follicle has a sebaceous gland attached to it. It secretes sebum, the oil of the scalp. Sebum is useful in:
- Lubricating hair
- Preventing dryness
- Guarding from infections by bacteria
- Maintaining good condition of scalp
- Less sebum means dryness while too much sebum leads to an oily scalp.
Arrector Pili Muscle
It is a small muscle that causes the body to experience "goose bumps". Whenever one feels cold or afraid, it contracts and causes the hair to rise. Even though its importance has decreased in the course of evolution, it still makes a very interesting part of the human body.
Why Hair Anatomy Is Important?
An expert who knows about hair anatomy will be able to:
Avoid damaging hair unnecessarily.
Suggest products and treatments for their hair.
Understand the consequences of color and chemical services on hair.
Select appropriate wigs, toppers, and hair extensions.
Instruct clients confidently.
Identify situations where a client needs to be referred to a dermatologist or trichologist.
Knowledge about hair anatomy does not only consist of theory but impacts each practical decision that you make.
Important Points:
There are two main components of hair: hair root and hair shaft. The hair shaft comprises three different layers: cuticle, cortex, and medulla. Cuticles are responsible for protection of hair. Cortex gives hair strength, elasticity, and color. Medulla is an innermost layer of hair and may not always be there. Hair develops from the hair follicle due to the presence of hair bulb, dermal papilla, sebaceous gland, and arrector pili muscle.
