humanbody structure

Showing posts with label hair. Show all posts
Showing posts with label hair. Show all posts

Tuesday, December 4, 2018

HAIR

HAIR




  • Any of the fine thread like strands growing from the skin of mammals,esp. from human head.
  • Hair is actually grow from dermis layer and they are mainly a protein filaments.
  • Each strand of hair is made up of the medulla, cortex, and cuticle.
  • The innermost region, is not always present and is an open, unstructured  region.
  • The highly structural and organized cortex, or second of three layers of the hair, is the primary source of mechanical strength and water up take.
  • The cortex contain melanin, which colors the fiber based on the number, distribution and types of melanin granules.
  • The shape of the follicle determines the shape of the cortex, and the shape of the fiber is related to how straight or curly the hair is.





HAIR GROWTH CYCLES:

There are total 3 cycles for hair growth, they are as below:

  1. Anagen(grow phase): Most hair is growing at any given time.Each hair spends several years in this phase.
  2. Catagen phase( transitional phase): Over a few weeks, hair growth slows and the hair follicle shrinks.
  3. Telogen( resting phase): Over months, hair growth stops and the old hair detaches from the hair follicle. A new hair begins the growth phase, pushing the old hair out.





OTHER FACTS ABOUT HAIR:

  • Everyday the average person loses 60-100 strands of hair. And this is happen because of the season, pregnancy illness, diet and age.
  • Hair only grows 0.3 - 0.5 millimeters each day. Or about 1 cm every month. so this means that it can keep this life diary for a long time- for a month or even year.
  • The average human has 100,000 hair follicles or above.
  • The life span of human hair is 3-7 years.

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