Why do humans moult hair?

Answer 1

Hair is also a life-cycle, when the growth to a certain extent will naturally fall off as a result of metabolism, and this is one of the reasons why hair loss.




1, to understand the hair growth cycle, hair loss will understand why.



The growth of hair in three phases, namely: growth phase, catagen and telogen.



(1) growth



Also known as active growth, growing a sustainable 4-6 years or even longer, was active proliferation of hair, and hair ball speed up the lower part of cell division, cell differentiation hair ball out of the upper cortex, hair cuticle; increased dermal papilla, to speed up cell division, the increase in the number. Melanoma of the original non-active dendritic growth process, the beginning of the formation of melanocytes.



(2) catagen


Also known as the degradation period of contraction or for a period of 2-3 weeks. Cessation of active proliferation of hair to form a hair-shaped pestle, the bottom for eosinophilic homogeneous material, bamboo rod was around Week. Inner hair root sheath disappear gradually trichilemmal keratosis, hair ball flat, not sunken, gradually narrowing the dermal papilla, a decrease in the number cells. Dendritic cells lose black push process, but also round in shape, but no activity.



(3) telogen



Also known as the quiescent period or rest period for about 3 months. At this stage, hair follicles gradually shrink and have been aging in the vicinity of the hair follicle re-growth period to form a hair ball, and finally the old hair off, but at the same time will grow a new hair growth and re-entering the cycle to repeat. Department of the scalp -14% 9% telogen hair in only 1% in catagen, and eyebrows are in telogen 90 percent. Hair growth cycle in the proportion of each phase varies with the site.




2 from the correct understanding of life person and the type of hair loss why



Lead to hair loss there are many factors, both congenital or hereditary factors, but also acquired factors; both physiological reasons, but also a rational reason for the sick. However, acquired factors, that is, a number of pathological factors the most common cause of hair loss, such as the number of mental stress, acute and chronic Infectious Diseases, various skin diseases, endocrine disorders, physical and chemical factors, neural factors, nutritional factors, may result in hair loss. Chinese medicine practitioners believe that liver blood, the blood while the main renal medullary bone of Health, and its wing in hair, blood Sheng Qi is strong, full of kidney bone marrow strong, and shiny black hair, blood kidney qi deficiency is weak, gas Blood can not be up-rong Yang-hair, no hair is brown and off-taek, so that the formation of hair loss and lack of liver and kidney, qi and blood of the weak. At the same time, people were affected by injuries to the impassioned, emotional depression, heart-breaking labor spleen, the impact caused, hair loss and the loss of nutrition, which is the body of modern medical research endocrine disorders and immune disorders, mental trauma with excessive tension, blood vessels and blood circulation obstacle to such factors, leading to hair follicle dystrophy and alopecia consistent point of view. In recent years, clinical testing shows that the serum of patients with alopecia endothelin (ET) were significantly higher than normal. This can cause a strong contraction of local vascular spasm due to reduced local blood supply to the material, can lead to depletion of shedding hair. Hair and blood testing also confirmed that patients with scalp hair loss is not only organized and morphological changes, there is a high resistance to blood flow, blood volume less effective reduction of perfusion abnormalities.

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Answer 2

Humans dont "require" hair. They were just made with it for warmth.