Hair acquires important cosmetic value to people, with baldness and the presence of unwanted hair being a real problem.
To understand the cause of baldness and unwanted hair, it is necessary to study the structure, distribution, growth and the different types of hair.
Hair comes from the pilous follicle which is an extension of the skin, and has two types of hair:
Terminal hair: is the hair found on the scalp, eyebrows, eyelashes, nasal orifices, ear channels and sexual hair (armpits, pubis, chin and chest), all of which initially is vellus hair but androgenic action turns it into terminal hair.
They are long and course hairs. Their stem is made up of a cortex and a medulla, and it is pigmented. The intradermal part of the stem is called the root. This last, surrounded by the follicle, thickens and forms the bulb and the pilous matrix, vascularised by the papilla. The papilla and bulb are located in the deep dermis, even reaching as deep as the hypodermis. Attached to the follicular structure is the hair erector muscle and the sebaceous gland.
Vellus hair: the hairs that are all over the surface of the body except for on the palms of the hands, soles of the feet, mucosa and distal phalanges of fingers and toes.
This type of hair does not have a medulla or pigment and is it short and fine. Many of these hairs lack an erector muscle. The bulb is more superficial, located in the upper dermis.
Hair grows differently in the human being, depending on age, weight, metabolism, hormones, ethnic origins, medications, and other factors. But all hair passes through three different growth phases:
Anagen phase: is the active phase of hair growth, which lasts between 2 and 5 years. 85% of hair is in this phase. In this phase the hair has abundant melanin.
Catagen phase: is a period of regression which lasts from 2 to 3 weeks, where the growth of the hair stops but it does not fall out. Close to 3 to 4% of hair is in this phase.
Telogen phase: Constitutes the rest phase with minimal metabolic activity which lasts from 5 to 6 weeks. At the end of this phase, the hair falls out and 10 to 13% of hair is in this phase.
On the scalp there are some 100.000 follicles ( 615/cm2 )
Factors such as location on the body, follicular density (number of hairs per square centimetre) and the percentage of hair in each phase, results in their being no synchronised growth in human beings, and therefore the duration of time in each area is different.
PERCENTAGES
|
Área corporal |
% pelo telógeno |
% pelo anágeno |
Duración telógena |
Densidad folicular (cm2) |
Profundidad folículo |
|
Axilas |
70 |
30 |
3 m. |
65 |
3.5-4.5 mm |
|
Barba |
30 |
70 |
10 s. |
500 |
2-4 mm |
|
Bigote |
35 |
65 |
6 s. |
500 |
1-2.5 mm |
|
Brazos |
80 |
20 |
2-4 m. |
80 |
2-4.5 mm |
|
Cabeza |
10-15 |
85-90 |
3-4 m. |
350 |
3-5 mm |
|
Cejas |
85 - 95 |
5-15 |
3-4 m. |
50 |
2-2.5 mm |
|
Mamas |
70 |
30 |
10 s. |
65 |
3-4.5 mm |
|
Muslos |
80 |
20 |
2-3 m. |
60 |
2.5-4 mm |
|
Piernas |
80 |
20 |
3-6 m. |
60 |
2.5-4 mm |
|
Pubis |
65-80 |
20-35 |
12 s. |
70 |
|
|
Tronco |
80-90 |
10-20 |
4 m. |
70 |
3.5-4.5 m |
y=years ; m=months ; w=weeks ; mm=millimetres
Hair consists of: 28% protein, 2% lipids and 70% water; the most abundant protein is keratin, a protein composed of polypeptide chains very rich in cysteine; the principal elements are: carbon, hydrogen, oxygen, nitrogen and sulphur, in lesser quantities are: calcium, copper, cadmium, mercury, zinc, lead, iron, arsenic, silicon, magnesium, uranium, vanadium, sodium and potassium.
The melanin and pheomelanin content determine the greater or lesser darkness of the hair depending on the percentage of each. The thickness of the hair is proportionally related to the amount of pigment in same.
The depth of the pilous bulb varies depending on the anatomical location and the type of hair from 0.5 to 3mm.
The Clinical Capillary Institute has the latest technology to solve all types of baldness and unwanted hair.
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