Every human being has two types of hair on their body. These hair types are vellus and terminal hair. Terminal hair is hard and long hair that have a colour. They are likely to be wavy compared to other feathers, and they also have a thick structure. The amount of melanin is higher in terminal hair than vellus.
In the majority of men, terminal hair surround the face and body. They are generally longer than 2 cm, thick, concise and coloured. Both in women and men, the development of terminal hair in the body first develops in the armpits and groin.
In cases where testosterone levels are high, vellus hair is known to become terminal in men and women. For women, if the terminals are overloaded on the lips, jaws, necks, arms, thighs in the body back and abdominal region, it could be considered as male-type hair.
Hormone tests and physical examination may also be necessary to solve the problem. There are cases where excess hair does not pose a problem. This excessive hairiness in women is called hirsutism.
There are many causes of excessive hair growth, such as genetic and skin colour. Sometimes it is difficult to distinguish between two kinds, so the diagnosis of a specialist physician is very important. Hirsutism is probably the cause of hair follicular being sensitive to androgen hormone
The Way Terminal Hair Works
They form hair, eyebrows and eyelashes before puberty, and then replace the vellus hair. The growth of hair usually lasts until the age of 40, depending on sexual development.
Depending on the position and function, the size and shape of the terminal’s hair can vary. The ones on the scalp can protect against UV rays. Also, the ones on the eyebrows and eyelashes prevent dust and liquid from entering the eyes. In addition, nasal hair prevents insects and other airborne materials from entering the nasal cavity.
What is Vellus Hair?
Vellus hair is soft, well-modulated and poorly pigmented and cover the entire body except for the palms, soles, lips and genital areas. Females have more vellus hair than males. Vellus hair is very common for infants and children. In puberty, most vellus hair turn into terminal hair.
The difference between Terminal Hair and Vellus Hair
When it comes to vellus hair, we can say that they are soft fine hair and less pigmented, terminal hair is coarser and well pigmented.
The diameter of the terminal hair is generally more than 60 μm, whereas the diameter of the vellus hair is less than 30 μm.
In this sense, they are longer than vellus hair.
Unlike terminal hair, vellus hair follicles penetrate the reticular dermis and do not reach the subcutaneous fat layer.
You can observe vellus hair in many areas other than the palms, soles, lips and the genital regions. On the other hand, terminal hair on the scalp, underarms, pubic areas, and some other skin areas.
In some regions, vellus hair turn into terminal ones as a result of hormonal changes.