The hair is one of the most defining features of human beings. It comes in different colors, textures, and lengths. But what makes hair unique and distinct is its structure. In this article, we will explore the science behind hair structure.
What is Hair?
Hair is a protein filament that grows from follicles found in the skin. It is made up of three layers: the cuticle, cortex, and medulla. The cuticle is the outermost layer, and it protects the inner layers. The cortex is the middle layer, and it provides strength and texture. The medulla is the central core, and it gives hair its flexibility and elasticity.
The Hair Cuticle
The cuticle is the outermost layer of hair. It is a protective layer that safeguards the hair from external damage. The cuticle has an overlapping structure that looks like the shingles on a roof. This overlapping structure protects the cortex from damage and wear and tear. The cuticle is made up of flattened cells that are held together by a lipid layer. This lipid layer acts as a glue that holds the cells of the cuticle together.
Structure of the Cuticle
The cuticle is made up of several layers of cells that overlap each other like roof shingles. The cells are called cuticular cells. Each cuticular cell is made up of a protein called keratin. The keratin in these cells is arranged in a parallel manner, giving the cuticle its smooth appearance. The cuticle also contains a lipid layer that helps to hold the cells together.
Functions of the Cuticle
- Protects the inner layers of the hair from external damage
- Protects the hair from UV radiation
- Provides the hair with a smooth and shiny appearance
- Helps to retain the moisture in the hair
The Hair Cortex
The cortex is the middle layer of hair. It provides the hair with its strength and texture. The cortex is made up of cortical cells that contain a protein called keratin. Keratin is a fibrous protein that gives hair its strength and elasticity. The cortex is responsible for the color and texture of the hair.
Structure of the Cortex
The cortex is made up of long, thin cylindrical structures called cortical cells. The cortical cells contain a protein called keratin. The keratin in the cortical cells is arranged in a parallel manner, giving the cortex its strength and flexibility. The cortex also contains pigment granules that give hair its color.
Functions of the Cortex
- Gives hair its strength and flexibility
- Determines the color and texture of the hair
The Hair Medulla
The medulla is the central core of hair. It is only found in thick hair and not in all hair types. The medulla is responsible for the elasticity and flexibility of the hair.
Structure of the Medulla
The medulla is made up of round, hollow cells that are sometimes absent in fine hair. In thick hair, the medulla forms the innermost layer of the hair, and it is surrounded by the cortex and cuticle.
Functions of the Medulla
- Gives the hair its flexibility and elasticity
- Helps to prevent hair breakage
Types of Hair
There are different types of hair, and they have different structures. The three main types of hair are straight, wavy, and curly hair.
Straight Hair
Straight hair has a circular or oval cross-section. Its cortex is relatively straight, and it does not have a well-defined curl pattern. Straight hair is usually thicker than curly or wavy hair, and it reflects more light, giving it a shiny appearance.
Wavy Hair
Wavy hair has a flattened or oval cross-section. Its cortex is bent at an angle, giving it an S-shaped curl pattern. Wavy hair is less shiny than straight hair due to less reflection of light.
Curly Hair
Curly hair has a flattened, ribbon-like cross-section. Its cortex is tightly coiled, giving it a spiral or ringlet pattern. Curly hair is less shiny than straight hair due to less reflection of light.
Hair Growth Cycle
The hair growth cycle has three phases: anagen, catagen, and telogen. Each hair strand undergoes this cycle independently of neighboring strands. Understanding the hair growth cycle is essential in maintaining healthy hair.
Anagen Phase
The anagen phase is the active growth phase of the hair. During this phase, the hair follicle is actively producing new hair cells, and the hair is growing. This phase can last from months to years, depending on the length of the hair.
Catagen Phase
The catagen phase is a transitional phase that occurs after the anagen phase. During this phase, the hair stops growing, and the hair follicle shrinks. This phase lasts for only a few weeks.
Telogen Phase
The telogen phase is the resting phase of the hair. During this phase, the hair follicle is dormant, and the hair is not growing. In this phase, the hair is shed and replaced by a new hair strand. This phase lasts for several months.
Most Common Hair Problems
Hair problems are common and can be caused by a variety of factors. Here are some of the most common hair problems:
Hair Loss
Hair loss is a common problem that affects both men and women. It is caused by a variety of factors, including genetics, age, hormonal changes, and medical conditions. Hair loss can be treated with medication, surgery, or hair restoration techniques.
Dandruff
Dandruff is a common scalp condition that causes the skin to flake. It is caused by a yeast-like fungus that grows on the scalp. Dandruff can be treated with over-the-counter shampoos and topical treatments.
Dry Hair
Dry hair is a common problem that is caused by a lack of moisture in the hair. It can be caused by environmental factors, such as exposure to the sun, wind, and cold weather, as well as chemical treatments, such as coloring and perming. Dry hair can be treated with moisturizing shampoos and conditioners.
Conclusion
Hair structure is a complex topic that involves an understanding of the different layers that make up the hair. The cuticle, cortex, and medulla each play a critical role in the strength, texture, and elasticity of the hair. The hair growth cycle and common hair problems are also important topics to understand to maintain healthy hair. By understanding the science behind hair structure, you can take better care of your hair and prevent common hair problems.
References
- Khumalo, N. P., & Jessop, S. (2015). Hair disease in Africans: what’s new?. International journal of women’s dermatology, 1(4), 148-157.
- Jachowicz, J., & McMullen, R. (2019). Structural Changes in Keratin Fibers Induced by Alkaline Peroxide Cosmetic Formulations. International journal of trichology, 11(1), 1-5.
- Rogers, N. E., & Avram, M. R. (2008). Medical treatments for male and female pattern hair loss. Journal of the American Academy of Dermatology, 59(4), 547-566.
Most Common Questions and Answers
- What is hair made of? – Hair is made up of a protein filament called keratin.
- How many layers does hair have? – Hair has three layers: the cuticle, cortex, and medulla.
- What is the hair cuticle? – The hair cuticle is the outermost layer of hair that protects the inner layers.
- What is the hair cortex? – The hair cortex is the middle layer of hair that provides strength and texture.
- What is the hair medulla? – The hair medulla is the central core of hair that provides flexibility and elasticity.
- What are the different types of hair? – The three main types of hair are straight, wavy, and curly hair.
- What is the hair growth cycle? – The hair growth cycle has three phases: anagen, catagen, and telogen.
- What are the most common hair problems? – The most common hair problems are hair loss, dandruff, and dry hair.