Have you ever wondered why the hair on your head, eyebrows, and eyelashes are so different from the fine hair on other parts of your body? Those thick, slightly stiff, and visible hairs are what we medically call 'terminal hair'. These are very important for our bodies. So, today, let's talk about these 'terminal hairs' in simple terms.
What exactly is terminal hair?
Simply put, terminal hair is the type of hair that forms our eyebrows and eyelashes, as well as the thick hair on our heads. Once we reach puberty, these terminal hairs start to grow on our faces, armpits, private parts, chest, and even stomach. Most of the time, a woman's body is covered in these terminal hairs, covering about 30% of her body. In a man's case, this amount can be as much as 90%. Isn't that amazing?
What is the difference between Vellus Hair and Terminal Hair?
This is also very simple.
- Vellus hair: This is the very fine, light-colored hair that we have all over our bodies. You may have heard some people call it "peach fuzz." When we are young, that is, during childhood, we have the most vellus hair on our bodies.
- Terminal hair: As we age, hormonal changes in our bodies cause some vellus hair to turn into thicker, darker terminal hair.
You can find vellus hair on your face, neck, arms, legs, and chest. Vellus hair is usually shorter and lighter in color than terminal hair. Terminal hair, on the other hand, is longer and darker in color. Another thing is that terminal hair goes deeper into our skin than vellus hair.
What are the benefits of terminal hair?
Terminal hairs provide our bodies with various types of protection. Think about it this way:
- Body temperature regulation: Have you ever noticed that when you feel cold, your hair stands up? That's because our hair helps keep the air warmed by our body heat close to our skin, keeping us warm.
- Protection for the scalp: The hair on our head protects our scalp from the harmful rays of the sun.
- Eye protection: Eyebrows and eyelashes largely prevent things like sweat, dust, and dirt from entering the eyes.
- Ear and nose protection: Hair inside the ears and nostrils also reduces the entry of germs.
You see, these aren't just a few strands of hair, they do a very important job.
Where is terminal hair located?
We have terminal hair in many places on our bodies. For example:
- Head (skull)
- Armpit
- Secret areas
- Upper lip, cheeks, and chin (especially in men, but also to some extent in some women)
- Eyebrows and eyelashes
- Chest and stomach
- Outside
- Hands and legs
- Fingers (hands and feet)
How is the structure of a terminal hair formed?
Although we only see the hair shaft above the skin, it has a very complex structure underneath the skin. To be precise, each hair shaft has two parts : the hair shaft and the hair root .
- Hair shaft: This is the part of the hair that we see, protruding from the skin.
- Hair root: This is the part that extends deep into the layers of the skin.
Each hair follicle is surrounded by a sheath of skin and connective tissue called a hair follicle . Each hair follicle is connected to a small muscle. That's what makes our hair stand up (called a hair follicle). At the base of each hair shaft, the hair follicle widens and forms a spherical hair bulb . At the base of this hair bulb is the hair papilla . This papilla supplies the hair follicle with blood.
How does terminal hair grow?
This is a very amazing process. Inside each hair follicle, new hair cells continue to grow. These cells join together, thicken, and form a complete hair shaft. The newly thickened cells attach to the hair shaft underneath. The hair shaft then gradually pushes up and emerges from the skin. A hair shaft on our head typically grows about a centimeter per month. The hair on our body and face grows even faster.
What is the growth cycle of terminal hair?
Our hair goes through a three-phase cycle, and then starts over again.
1. Growth phase (Growth phase or Anagen phase):
This is the first phase of the cycle and the phase when the hair shaft is actively growing . As long as new hair cells are being produced, your hair will continue to grow. The length of the hair shaft is determined by where it is located on the body. For example, terminal hair on the scalp can grow for years. That's why it can grow over a meter long. However, the hair in your eyebrows and eyelashes has a very short growth phase. They only grow for about 100 to 150 days. That's why they don't grow very long.
2. Transitional phase or Catagen phase:
This is the second phase of the growth cycle. Once the growth phase is over, your hair follicle begins to separate from the papilla. This transitional phase is the shortest phase of the hair growth cycle. It usually lasts about two to four weeks.
3. Resting phase (Resting phase or Telogen phase):
This is the third and final phase of the growth cycle. Once the hair shaft has completely detached from the papilla, its blood supply is cut off. The hair shaft then slowly pushes up through the skin and eventually falls out. This resting phase can last for several months.
And then? New hair cells start to grow inside that hair follicle, and new hairs begin to grow. And so the cycle continues.
What is terminal hair made of?
Most of your terminal hair is made up of dead hair cells filled with a protein called keratin. As the hair shaft grows to the surface of the skin, the blood supply to the hair cells is cut off and the cells die. At the same time, the part that is visible from the scalp, the hair shaft, undergoes a process called keratinization . During this keratinization, the hair shaft becomes filled with keratin. So, your hair shaft is made up of a mixture of this keratin and cells that die during the normal growth process.
How is the color of terminal hair determined?
The color of your hair is determined by the amount of pigment, called ``melanin,'' inside your hair follicles. As you age, this melanin usually decreases. When melanin decreases, air is trapped inside the hair shaft. When this happens, the hair shaft loses its color and turns white. Depending on your original hair color and the amount of white hair that develops, the hair on your head may turn gray or completely white.
What happens to terminal hair during puberty?
As we age, our hormone levels begin to rise. Our body's endocrine system produces more hormones called androgens . This increase causes the fine vellus hair in some areas of the body to turn into terminal hair. Vellus hair, especially in the armpits and genital areas, becomes terminal hair.
As some young children reach puberty, the vellus hair on their upper lip, cheeks, and chin turns into terminal hair. Terminal hair also begins to grow longer on their upper back, chest, knuckles, arms, and legs.
What diseases and conditions affect terminal hair?
There are several conditions that can cause excessive hair growth or hair loss.
Alopecia - hair loss
The average person sheds about 100 hairs a day. That's normal. However, as you age, the rate of hair growth slows down. Additionally, if your hair follicles are damaged during the growth phase, and too many hairs go into the resting phase at once, you may experience hair loss, also known as alopecia .
Alopecia is a condition where new hair does not grow to replace the hair that has fallen out. There are several types of alopecia. In some types of alopecia, hair may regrow. Alopecia is a common condition that can be caused by a number of factors. Other causes of alopecia include:
- Autoimmune diseases : These are diseases in which our body's immune system attacks our own cells.
- Certain medications : Some medications can cause hair loss as a side effect.
- Hormonal imbalance : This condition can also be caused by changes in hormones.
Alopecia areata
This is an autoimmune disease. Your immune system attacks your own body. This condition causes your hair to fall out in large patches . Alopecia areata can affect hair anywhere on your body. However, it most commonly affects the scalp. The amount of hair loss can vary. Sometimes, it's just in patches. Other times, you may lose all of your hair. Treatment options may include using an anti-inflammatory medication like a corticosteroid or a topical medication like Minoxidil (Rogaine®) .
Androgenetic alopecia
This is a genetic condition , meaning it is passed down from generation to generation. It causes the hair on the scalp to gradually fall out after puberty. This condition is caused by a type of androgen called dihydrotestosterone (DHT) damaging the hair follicles. The hair follicles then shrink and start producing short, thin, vellus-like hair. Androgenetic alopecia is treated with topical minoxidil and medications such as finasteride (Propecia®) . This condition affects both men and women:
- Male pattern baldness: This is a type of androgenetic alopecia that affects men. Hair loss most often occurs on the top of the head and the sides of the forehead. You may have heard the term "receding hairline."
- Female pattern hair loss (FPHL): This is a type of androgenetic alopecia that affects women. The hair loss occurs on the top and front of the head, but does not affect the hairline at the forehead. You may notice a widening of the middle part of your head.
Hirsutism - abnormal hair growth in women
During the reproductive years of women, hormonal imbalances can lead to hair growth disorders such as hirsutism. Hirsutism is the growth of terminal hair in women in addition to the normal hair growth pattern in men. This condition is caused by an increase in androgen hormones. The most common cause of hirsutism is a hormonal disorder called Polycystic Ovary Syndrome (PCOS) . Treatment options include hair removal and hormonal medications such as birth control pills.
Hypertrichosis - excessive hair growth
Hypertrichosis is an excessive growth of hair anywhere on the body, not due to an increase in androgen levels. It is usually caused by certain medications . Sometimes, it can also be caused by certain medical conditions. It can affect anyone, regardless of gender. Treatment usually involves laser hair removal, depilatory creams, and/or electrolysis . In most cases, stopping the medication that caused the condition will help reverse the symptoms.
What is a terminal hair cyst?
A terminal hair cyst is a rare type of epidermoid cyst . An epidermoid cyst is a small lump of keratin that forms under your skin. A terminal hair cyst is a brown-black or blue lump on your skin. It may have a hole-like opening on its surface. These cysts are most often found on the head or neck. They are usually noncancerous (benign).
Terminal hair is the dark, thick type of hair on our scalp and body. It goes through a constant cycle of growth, shedding, and resting, before starting over again. You probably don’t think much about your terminal hair. But if you have a condition that causes hair loss or excessive hair growth, know that you’re not alone. About 50% of the population has some type of hair-related condition or disorder. Talk to your doctor about the treatment options that are best for you.
The most important things we want to take home from this article (Take-Home Message)
Okay, so we've talked a lot about terminal hair today, haven't we? Here are some of the most important things to remember:
- Terminal hair is the thick, dark hair that grows on our scalp, eyebrows, eyelashes, and other parts of the body as we age.
- These protect our bodies and help regulate body temperature.
- Hair follicles also have a growth cycle : the growth phase (anagen), the transition phase (catagen), and the resting phase (telogen).
- Hair color is determined by a pigment called melanin .
- Conditions such as alopecia ( hair loss) and hirsutism (abnormal hair growth in women) can affect terminal hair.
- If you have any hair-related problems, don't be afraid to seek medical advice. There are effective treatments for that.
So, take care of your hair, because it's also part of your overall health!
` Terminal hair, hair growth, hair loss, alopecia, hirsutism, hair structure, body hair
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