vkb247
Well-Known Member
Seems like the Terminal Growth: Fact or Fiction? thread http://www.longhaircareforum.com/showthread.php?t=133117 is turning into the thread that will never end so I thought I would post what I learned about how hair grows here to help clarify some good points that have been raised, particularly by Mwedzi.
The basics:
Everyone's hair grows differently, depending on age, weight, metabolism, hormones, ethnicity, medications, and other factors. But all hair goes through three distinct growth phases:
1) Active growth phase (anagen phase)
-lasts up to several years
-at any given time, the majority (85%) of our hair is in this phase
2) Regressive phase (catagen phase)
-lasts about two weeks, during which the hair stops growing but is not yet shed
-3 - 4% of our hair is in this phase at any given time
3) Resting phase (telogen phase)
-lasts 5 - 6 weeks, at the end of which the hair falls out and a new hair begins to form.
-Approx. 10-13% of our body hair is in this phase at any one time
http://www.alpha7haircare.co.uk/contents/media/hair growth cycle illustration.jpg
As soon as the growth phase is complete, degeneration begins. As catagen proceeds, the blood vessels at the base of the follicle (dermal papilla) still remain intact, but they finally disappear.
Telogen hair or clubbed hair is easily recognized because it generally contains a thin shaft, which is transparent near the root and devoid of a medulla and keratogenous zone. Epilated (removed by physical, chemical, or radiological agents) telogen hair may be wrapped in the remains of an epithelial sac, which is absent from nongrowing, spontaneously shed clubbed hair.
During the Telogen Phase, the hair has become completely dormant. It is no longer connected to anything substantial and it is preparing to fall out. This hair will shed once a new Anagen hair begins to form below.
To specifically answer Mwedzi's question:
Cell division in the hair matrix is responsible for the cells that will form the major structures of the hair fiber and the inner root sheath. The hair matrix epithelium is one of the fastest growing cell populations in the human body, which is why some forms of chemotherapy that kill dividing cells or radiotherapy may lead to temporary hair loss, by their action on this rapidly dividing cell population.
From what I have learned it seems that:
- hair is cells that are dividing over and over again or growing
- the hair stops growing when triggered but no one knows what the trigger is
- the hair then begins to degenerate and all the blood vessels and other things that help the cells to divide move away from the strand of hair (resting phase)
-our non-growing hairs will continue to sit there until another hair starts to grow and pushes it out of the way or the hair is removed from the scalp unnaturally
- the white bulb that we see at the ends of some hairs when they are shed is an indication that this hair was not shed naturally because only telogen hair that is removed by physical, chemical, or radiological agents should have this sac attached.
I found most of this info here:
http://www.forhair.com/hair_growth.htm
The basics:
Everyone's hair grows differently, depending on age, weight, metabolism, hormones, ethnicity, medications, and other factors. But all hair goes through three distinct growth phases:
1) Active growth phase (anagen phase)
-lasts up to several years
-at any given time, the majority (85%) of our hair is in this phase
2) Regressive phase (catagen phase)
-lasts about two weeks, during which the hair stops growing but is not yet shed
-3 - 4% of our hair is in this phase at any given time
3) Resting phase (telogen phase)
-lasts 5 - 6 weeks, at the end of which the hair falls out and a new hair begins to form.
-Approx. 10-13% of our body hair is in this phase at any one time
http://www.alpha7haircare.co.uk/contents/media/hair growth cycle illustration.jpg
As soon as the growth phase is complete, degeneration begins. As catagen proceeds, the blood vessels at the base of the follicle (dermal papilla) still remain intact, but they finally disappear.
Telogen hair or clubbed hair is easily recognized because it generally contains a thin shaft, which is transparent near the root and devoid of a medulla and keratogenous zone. Epilated (removed by physical, chemical, or radiological agents) telogen hair may be wrapped in the remains of an epithelial sac, which is absent from nongrowing, spontaneously shed clubbed hair.
During the Telogen Phase, the hair has become completely dormant. It is no longer connected to anything substantial and it is preparing to fall out. This hair will shed once a new Anagen hair begins to form below.
To specifically answer Mwedzi's question:
Cell division in the hair matrix is responsible for the cells that will form the major structures of the hair fiber and the inner root sheath. The hair matrix epithelium is one of the fastest growing cell populations in the human body, which is why some forms of chemotherapy that kill dividing cells or radiotherapy may lead to temporary hair loss, by their action on this rapidly dividing cell population.
From what I have learned it seems that:
- hair is cells that are dividing over and over again or growing
- the hair stops growing when triggered but no one knows what the trigger is
- the hair then begins to degenerate and all the blood vessels and other things that help the cells to divide move away from the strand of hair (resting phase)
-our non-growing hairs will continue to sit there until another hair starts to grow and pushes it out of the way or the hair is removed from the scalp unnaturally
- the white bulb that we see at the ends of some hairs when they are shed is an indication that this hair was not shed naturally because only telogen hair that is removed by physical, chemical, or radiological agents should have this sac attached.
I found most of this info here:
http://www.forhair.com/hair_growth.htm
