Hair is an intriguing feature of human biology, serving both functional and aesthetic purposes.
It is a protein filament that emerges from follicles nestled within the dermal layer of the skin.
Across different species of mammals, hair plays a variety of roles including thermal regulation, protection from external elements, and even communication through visual cues.
In humans, it has significant social and cultural importance, influencing identity and personal style.
The composition of hair is primarily keratin, a robust protein that is also integral to the resilience of nails and the outer layer of skin.
Each strand of hair comprises a shaft, the visible segment above the skin, rooted deep into a follicle.
Within the follicle lies the hair root, a critical part of the hair that determines its growth and health.
By maintaining the health of the scalp and follicles, humans can influence the appearance and quality of their hair.
Hair color and texture are determined genetically, with the pigmentation given by melanin, and it can be altered by environmental factors and personal health. Do you want to know what is hair made of? We have the answers as we look into the anatomy of human hair.
Chapter Overview
Key Takeaways
- Hair’s main component is keratin, a protein that strengthens both hair and nails
- The follicle is the growth powerhouse of hair, affecting both its health and appearance
- Hair characteristics like color and texture are genetically set but can change with health and environmental factors
Basic Hair Anatomy
When talking about hair, it’s easy to just focus on what we see, but there’s a whole world underneath that’s essential for each strand’s life cycle and characteristics.
Hair’s complexity starts below the surface of the scalp in the hair follicle and manifests through the hair shaft that we style and admire.
Hair Follicle
The hair follicle is where every hair strand begins its journey.
Nestled deep in the layer of skin called the dermis, the follicle is not just a tunnel out of which hair grows; it’s a dynamic structure made of several parts.
At its base lies the bulb, a swell that houses the dermis and includes cells that produce the hair’s structure.
Surrounding the follicle, one can find tiny muscles called arrector pili that create goosebumps when they contract.
| Follicle Component | Description |
|---|---|
| Papilla | Contains capillaries that nourish the cells. |
| Matrix | Produces the hair shaft and inner root sheath cells. |
| Sebaceous Gland | Secretes oils to condition hair and skin. |
Hair Shaft
The hair shaft is the visible part of hair and is made up of three distinct layers:
- Cuticle: This is the protective outer layer. It’s made of overlapping scales that control moisture absorption and protect the inner layers
- Cortex: The cortex gives hair its shape and color, containing melanin, the pigment that determines hair color, and it’s made mostly of keratin, a protein that gives hair its strength
- Medulla: This is the central core of the hair, which can be absent in finer hair. It doesn’t have a defined function, but it forms part of the hair’s overall structure
Each of these layers plays a crucial role in the health and appearance of hair.
When these layers are nurtured and protected, they help maintain strong, vibrant hair that can withstand daily demands.
Whether hair is curly or straight, thick or thin, every strand of hair reflects the fascinating complexity of its structure.
Hair Growth Cycle
Understanding the hair growth cycle is key to realizing why hair grows the way it does. Now that we talked what is hair made of, let’s talk about the natural growth cycle.
Each strand of hair on one’s head is at a different stage of this cycle, which is why regular hair shedding is normal, but the hair still maintains its overall density.
Anagen Phase
The Anagen Phase is the growth phase where the hair actively grows.
Stem cells in the hair follicle multiply, and hair strands push up and out of the scalp.
This phase typically lasts about 2 to 7 years and determines the length of our hair. The longer a hair strand stays in the anagen phase, the longer it will grow.
Catagen Phase
The Catagen Phase is a transitional stage that lasts about two weeks.
During this brief period, the hair follicle shrinks, and the part of the hair that is actively growing (the lower end) detaches from the blood supply.
This process serves as a preparation for the hair follicle to renew itself for another anagen phase.
Telogen Phase
Finally, the Telogen Phase is the resting phase.
For about three months, the hair doesn’t grow but doesn’t fall out either. At any given moment, 10-15% of hairs are in this phase.
Think of it as a well-earned break for one’s hair before falling out, which is totally normal and makes way for a new hair to begin the cycle again with the Anagen Phase.
Hair Color and Texture
When it comes to hair, two features really define how it looks: the color and the texture.
Pigmentation
Hair gets its color from two types of melanin: eumelanin and pheomelanin.
These pigments vary in concentration and ratio, influencing a diverse palette of hair colors.
Eumelanin comes in black and brown varieties, dictating darker hair colors, while pheomelanin is responsible for red and yellow hues, giving rise to hair colors from blonde to red.
- Eumelanin: Determines shades from black to brown
- Pheomelanin: Gives blonde and red colors
The color of someone’s hair can shift over time, notably turning gray or white as melanin production decreases with age.
Hair Shape
The shape of an individual’s hair is largely determined by the structure of the hair follicle.
Straight hair typically has a round follicle, while curly hair comes from a more oval or irregularly shaped follicle. Here’s a quick look:
- Straight hair: Round follicle
- Curly hair: Oval or irregular follicle
The follicle’s shape influences the form of the hair’s cortex, which subsequently affects the hair’s overall texture – be it poker straight or springy curls.
Each hair type has its charm and challenges, but they all share the need for proper care to maintain their unique beauty and health.
Health and Care of Hair
Maintaining healthy hair and scalp is crucial for overall hair condition.
Factors such as proper nutrition, regular cleansing, and protection from damage play significant roles.
Let’s dive into the specifics of scalp health, hair damage and protection, and hair care practices.
Scalp Health
The scalp is the soil from which hair springs. A healthy scalp is essential to foster hair growth.
The sebaceous glands in the scalp secrete sebum, a natural oil that maintains moisture and health of both hair and scalp.
Regular cleansing is crucial to prevent buildup that can lead to issues like dandruff and scalp acne. However, too much washing can strip away the natural oils, so finding the right balance is key.
Nutrition also plays a role; a well-balanced diet rich in vitamins and minerals supports scalp health and can potentially mitigate hair loss problems like alopecia.
Hair Damage and Protection
Hair can be damaged by external factors such as sun exposure, high heat from styling tools, and harsh chemical treatments.
Protection involves minimizing heat styling, using UV hair protectants, and opting for gentle hair dyes.
Regular trims help prevent split ends from worsening.
It’s a common misconception that hair itself can be repaired once damaged, but actually, the focus should be on preventing damage and taking care of new growth.
Hair Care Practices
Effective hair care practices are tailored to individual hair types and needs.
Conditioners and hair masks can replenish moisture, especially for curly hair that tends to be drier.
Ingredients such as aloe vera and natural oils can nurture the hair.
When handling hair, it’s advisable to use a wide-tooth comb to detangle gently.
Understanding one’s hair type is key to avoiding misconceptions and adopting suitable hair care practices that contribute to hair’s health and appearance.
Hair Across Different Stages of Human Life
Hair is as dynamic as life itself, evolving from the cradle to the later years. Each stage of human development brings changes to the hair’s texture, type, and growth patterns.
Hair Changes Through Time
From the moment a person is born, their hair starts a journey through various stages.
In the initial months of life, babies flaunt a fine, soft coat of vellus hair that is mostly unpigmented. This includes the barely there eyelashes and eyebrows. Some infants are born with lanugo—a layer of soft, downy hair that they usually shed before or shortly after birth.
The transition isn’t abrupt. As a child grows, the vellus hair transforms gradually.
Upon reaching puberty, hormones usher in a new era for hair. Terminal hair, which is thicker and more pigmented, begins to replace the vellus hair at certain parts of the body.
- Scalp hair: Typically remains thick and may even increase in density during puberty
- Eyebrows and eyelashes: Generally become more pronounced and define the facial features
During their lifetime, an individual’s scalp hair may go through periods of thickening and certainly through cycles of shedding and growth.
Hair growth can be influenced by various factors, including genetics, nutrition, and environmental factors.
As age advances, the cycle of hair growth slows down, which might lead to thinner scalp hair. In many cases, the hair thins out, loses its pigment, and the texture may become finer. This part of the hair’s lifecycle reflects the culmination of years of change, a natural progression as the hair returns closer to the state of vellus hair, with which one’s journey began.