Hair is important for many people. But actually we really pay attention to our hair when there are problems with it, such as hair loss. And that while the process of hair growth is quite interesting. Did you know, for example, that the number of hairs on your head is already fixed at birth? And that your head hair refreshed about twenty times during your life?
We are born with all our hair follicles in place. Hair follicles can change size, but we do not develop new ones after birth. Men generally have more hair than women. The men have between 150,000 and 180,000, women between 130,000 and 150,000. Every day we lose between fifty and one hundred.
What we call her are actually dead hair cells. The living part of the hair is invisible under the skin; the hair root. The hair root is stuck in a hair follicle, a kind of bag in the skin. Sick glands and muscles also belong to that follicle. The hair root is always under the skin. This determines the direction of growth. The hair is provided by blood vessels that supply nutrients. The quality of your hair is also determined by the nutrients with which the hair root is nourished. Hair grows on average about 0.35 millimeters per day and has a diameter of about 0.05 millimeters. Bearded hairs grow about 0.38 millimeters every day and eyebrows grow 0.16 millimeters.
Nerve pathways ensure that we feel that our hair is touched when you walk through it with your hands, for example. The whole hair (root and shaft) is built up from the inside out of marrow, bark and a scaly layer. Around the hair root is a root sheath. The hair marrow is very thin, the bark (cortex) is the thickest part of the hair. The bark consists of elongated cells that form strands, the macro and microfibrils. The fibrils are held together by a kit substance (matrix). They are separated by cell membranes. The hair mainly consists of the protein keratin. This is elastic and can absorb water.
Her grows and renews constantly. New cells are formed at the bottom of the hair root. These move to the surface of the skin. They change along the way. Eventually they hear and form the hair shaft. The growth of the hair is divided into three phases.
The growth phase
Hair is in the growth phase for about two to six years, also called the anagen phase. In this period the hair root provides so-called ‘hair cells’ that are formed from all kinds of nutrients. New hair cells are pushed into the hair root canal one behind the other, as a result of which the existing hair cells move up and come out more and more. Hair grows about 0.35 millimeters daily and can grow to about 25 to 70 centimeters in the growth phase. About 85 to 90 percent of our hair is in the growth phase.
In the transition phase, or catagen phase, the hair has reached its maximum length and is preparing to drop out. From this moment the hair no longer grows. The hair follicle shrinks, the skin surface is closed, as it were, and the hair root is less firmly anchored in the skin. The transition phase lasts one to two weeks. Only 1 to 3 percent of all your hair is in the transition phase.
The rest phase
The resting phase, or the telogen phase, is the last phase in the hair cycle. The old hairs are emitted by new hairs in this resting phase. However, the hair will remain in the resting phase for about one to three months before it fails.
This whole process repeats itself about twenty times. This means that baldness will occur earlier in people with a short growth phase than in people with a long growth phase.
And the color?
In the hair bark are dyes, melanin, which provide the color of our hair. The color is made at the bottom of the hair root by pigment cells and slides out with the growth of the hair. There are two types of melanin that occur in the hair in different proportions. People with dark hair have more eumelanin, people with blond or red hair have more phaeomelanin.