Written by Gynne Ross Q. Ancheta

Edited and Reviewed by Reuben J C. Los Baños, Ph.D.

Have you ever wondered what our hair is composed of? Let me take you back to the basics! It is composed of a protein called keratin, a fibrous structural protein.

In the hustle and bustle of life, we tend to get overwhelmed by chores and issues and forget to stop for a moment to enjoy the little marvels that abound. But occasionally, in the simplest of things—such as a single strand of hair—we see beauty, intricacy, and even a lesson in slowing down.

Is it only found in your hair? No. Keratin is also found in your skin and nails. It provides strength, structure, and resilience to hair strands.

You may ask, what microscopic layers make up the hair?

1. Cuticle – the outermost layer. It is made of overlapping cells that protect the inner layers. It is responsible for the hair’s shine and smoothness and is a barrier against physical and chemical damage.
2. Cortex – the middle layer. It contains keratin and melanin. This layer provides strength and elasticity. This layer determines the texture and curl pattern of the hair.
3. Medulla – the innermost layer. It is sometimes absent in finer hair. It has a more spongy structure. It plays a role in the hair’s structure and flexibility.

The keratin comprises amino acids, primarily cysteine, which form strong disulfide bonds. These bonds are what give hair its strength and shape. Also, hair contains small amounts of lipids, water, and minerals.

What are the characteristics of the hair? Let me take you on a more profound look! Your hair has several characteristics:

1. Color can vary from black, brown, blonde, gray, or white. It is determined by the amount and type of melanin in the hair.
2. Length refers to how long the strands are. It can vary from very short to extremely long. However, it depends on how much it has grown and whether it has been cut.
3. Texture describes the feel and appearance of the hair. It can be fine, medium, or coarse. It also refers to whether the hair is straight, wavy, or curly.
4. Thickness refers to the density of the hair strands on the scalp. You may have thick, full hair, while others may have thin or sparse hair.
5. Shape can be round, oval, or flat, influencing whether the hair is straight, wavy, or curly.
6. Condition describes the health of the hair. Healthy hair is shiny, smooth, and strong, while damaged hair is dry, brittle, or frizzy.
7. Style refers to how the hair is arranged or groomed. It could be natural, braided, tied up, or styled with tools and products.

It is important to note that each characteristic can vary from person to person.

Here is a fun fact for you! Your hair characteristics can change due to genetics, age, and hair care practices.

What kind of cells are in hair?

The protein keratin is produced by specialized cells called keratinocytes. These cells originate in the hair follicle, located in the dermis, the middle layer of the skin.

Here is how it works:

1. Hair follicle and keratinocytes – The hair follicle is a tiny structure in the skin where hair grows. Inside the follicle, keratinocytes multiply and produce keratin, a tough and fibrous protein that gives hair strength and structure.
2. Hair Shaft Formation – As keratinocytes move upward through the follicle, they die and become part of the hair shaft. When the hair emerges from the skin, it is made of dead keratinized cells. This is why the visible part of your hair is not “alive.”
3. Melanocytes – Another type of cell in the hair follicle is the melanocyte. These cells produce melanin, the pigment that gives hair its color. The amount and type of melanin determine whether your hair is black, brown, blonde, or red.

The primary cells in hair are keratinocytes (which produce keratin) and melanocytes (which provide pigment). Once the hair grows out of the follicle, it comprises dead keratinized cells.

If you are uncertain whether hair is a protein or a cell, here is a breakdown!

Hair is primarily made up of a protein called keratin, a fibrous structural protein found in nail and skin. It is responsible for the strength and structure to the hair strand.

Hair itself is not a living cell. The part of the hair you see (the shaft) is made of dead keratinized cells that have been pushed out of the hair follicle. The living part of the hair is in the follicle beneath the skin, where cells divide and grow to form the hair strand. So, while hair is not a cell, it is made of protein and originates from living cells in the follicle.

Is hair an organ or tissue?

Hair is considered a tissue, not an organ. Here’s why:

In biology, an organ is a structure of multiple types of tissues that work together to perform a specific, complex function. For example, the heart is an organ because it contains muscle, connective tissue, and nerve tissue, all working together to pump blood.

On the other hand, a tissue is a group of similar cells that perform a specific function. Hair comprises keratinized cells, specialized cells that produce keratin, a tough protein. These keratinized cells form a structure (the hair shaft) but don’t combine with other tissue types to create a complex organ.

Hair itself is just a single type of tissue. However, the hair follicle, the structure in the skin that produces hair, is more complex. The follicle contains multiple tissue types (epithelial, connective, and sometimes muscle tissue), so it could be considered part of an organ—the skin.

The hair itself is a tissue, not an organ, because it is made of one type of specialized cell and doesn’t have the complexity of an organ.

What part of the hair contains DNA?

Hair is made up of two main parts:

The shaft (the visible part above the skin) and the root (the part below the skin, inside the follicle). The shaft is made of keratin, a protein, and does not contain any DNA because it consists of dead cells. The root, however, is located within the hair follicle under the skin.

This is where living cells are present, and these cells contain DNA. Specifically, the DNA is found in the nucleus of the cells in the root. When hair is pulled out with the root attached, it often contains follicular tissue rich in DNA. This is why hair with the root is used in forensic investigations for DNA analysis.

FUN FACTS!

1. Hair is mainly made of keratin. This is the same protein that makes up your nails and the outer layer of your skin.
2. Hair grows fast. Hair is the second fastest-growing tissue in the human body, after bone marrow. It grows about 0.5 inches (1.25 cm) per month.
3. You have a lot of hair. The average person has about 100,000 to 150,000 hair strands on their scalp. Blondes tend to have the most hair, while redheads have the least.
4. Hair is strong. A single strand of hair can support up to 100 grams of weight. Combining all the hair on your head could support the weight of two elephants!
5. Hair is mostly water. About 25-30% of your hair’s weight is water. This is why it feels heavier when wet.
6. Hair color is determined by melanin. The amount and type of melanin in your hair determine its color. As you age, melanin production decreases, leading to gray or white hair.
7. Hair is dead. The visible part of your hair (the shaft) is made of dead cells. Only the root in the follicle under the skin contains living cells.
8. Hair can “feel” things. While hair itself doesn’t have nerves, the follicles are surrounded by nerve endings. This is why you can feel a light touch or movement on your hair.
9. Hair grows in cycles. Hair growth happens in three phases: anagen (growth phase), catagen (transition phase), and telogen (resting phase). About 85-90% of your hair is in the growth phase at any given time.
10. Hair can reveal your health. Hair can store information about your diet, drug use, and environmental exposure. This is why hair samples are sometimes used in forensic or medical testing.

Hair is more than just an aspect of our looks—it’s a remarkable structure made mainly of keratin, molded by   living   cells,   and shaped by   our   genetics, surroundings, and grooming habits. While the hair we see is dead, its roots are alive, secreting a tissue that mirrors our identity and gives us important clues about our health and way of life.

By learning about hair’s layers, structure, and microscopic characteristics, we appreciate a taken- for-granted aspect of life. So the next time you catch a glimpse of yourself in the mirror, remember—your hair has a tale of biology, toughness, and uniqueness.

As we’ve seen, hair isn’t just a mere styling subject. It’s a fantastic structure composed of keratin, molded by living cells, and affected by our biology, habits, and grooming. From its microscopic layers to its capacity to reflect our well-being, hair is an incredibly compelling testament to how even the most mundane aspects of our body contain monumental design and function.

So the next time life gets too much, remember: there’s worth in the fundamentals. In learning to see and appreciate even   the little things,   such as our   hair,   we find again a   sense of awe and appreciation for ourselves.

References:

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Kingsley, A. (2022, April 11). The Hair Structure. Https://Www.philipkingsley.co.uk/. https://www.philipkingsley.co.uk/hair-guide/hair-science/the-hair-structure.html

Magtiza, A. (2021, February 19). 2.2 Hair and Scalp Assessment. Opentextbc.ca; BCcampus. https://opentextbc.ca/haircolourforhairstylistslevel2/chapter/consultation/

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Radhakrishnan, R. (2024, May 28). What Are the Four Types of Hair? MedicineNet. https://www.medicinenet.com/what_are_the_four_types_of_hair/article.htm

Specific Hair Follicular Keratinocyte Cell Types – CZ CELLxGENE CellGuide. (2025). Cellxgene Data Portal. https://cellxgene.cziscience.com/cellguide/CL:2000092

Watson, K. (2020, September 11). Is Hair Made of Dead Skin Cells? Healthline; Healthline Media. https://www.healthline.com/health/is-hair-dead#hair-growth

What Is Hair Made Of? – L’Oréal Paris. (n.d.). L’Oréal Paris.

https://www.lorealparisusa.com/beauty-magazine/hair-care/all-hair-types/what-is-hair- made-of-structure-anatomy

Wikipedia Contributors. (2019, June 3). Hair. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/Hair