There are hair follicles everywhere in the skin. These are formed in a baby even before it is born. After birth, new hair follicles no longer appear. Every hair follicle contains the beginning of a hair. This beginning is the hair root and is the part of a hair that is under your skin. The blood brings food and oxygen to the root via a blood vessel. The root needs these substances to grow the hair. The part of the hair that has grown this far and extends beyond your skin is called the hair shaft. An important substance in the hair is keratin: this is a hearing substance. Keratin makes hair so strong.
Hair follicle
Each hair has its own hair follicle. The hair follicle is located approximately 4 millimeters under the skin. Nowhere in the body are so many cells produced as in a hair follicle. In fact, everything is determined in a hair follicle, namely the color and style, for example curly hair. The color of the hair is created by the interplay between the hair and the light that falls on it. The naked eye sees colors in hair. When a hair is placed under the microscope, it becomes clear that a hair is invisible.
Grow
Every hair has its own life. Hair grows on the bottom. New cells are made under the skin and push the old cells through the scalp. The growth of a hair can be divided into three stages: the anagen phase is the growth phase. The second phase, the catagen, is a transition phase. The hair root is loosened and moves to the skin surface. Finally, there is the resting phase, the telogen. This ends with the expulsion of the old hair by a new anagen hair. The process repeats itself again and again. The duration of these different phases depends on the part of the body in which the hair grows. In adult scalp hair, the anagen phase lasts between two and six years. The catagen lasts only a few weeks and the telogen phase in turn lasts several months. The hairs of the eyelashes, eyebrows and torso only last three to six months. In principle, each hair follicle can produce new hair on the scalp 25 times. The average growth phase of a hair lasts about three years. So one hair follicle can last for about 75 years.
Grey hair
Old people often get gray hair. This is because the melanocytes (the cells that produce pigment) are no longer replaced. This means that no pigment enters the hair, making it white. All hairs do not turn white at the same time, this happens in phases.
Research
If you examine a hair closely, you can find out what someone has eaten or drunk lately. You can also find out whether someone has smoked. This is because hair absorbs all kinds of substances. Hair can also ensure that the perpetrator of a crime is traced. If the police find a hair at the scene of a robbery, they keep it carefully. The hair is examined in a laboratory. Based on such a DNA profile, the perpetrator can be identified and ultimately used as evidence against a suspect.
Head lice
A louse is a parasite that lives on human blood. The animal grows to about 4 millimeters in size and attaches itself to the hair of a person’s head with its legs. The louse eats two to three times a day. Because a louse loses saliva when sucking, you get itching. If you have lice, you can only tackle them with anti-lice products.
Facts
- About 200 hairs grow on one square centimeter. On average, about 100,000 hairs grow on the entire head.
- Asian people naturally have more hair, about 120,000.
- Red-haired people have the least hair: about 80,000.
- Hair plays an important role in many religions and ancient traditions. You leave your beard or shave the top of your head. This sets you apart from people who do not believe. There are also religions where the hair of a newborn baby is cut off and thrown into a river. By cutting off the hair, the baby breaks away from his or her mother and starts its own life.