It exists within thedermisand theepidermis, the two top layers of the skin.
Papilla
The papilla is made up of connective tissue and blood vessels that nourish growing hair.
It exists at the very base of a hair follicle.
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It is also located in the lower region of the hair follicle.
This is the living part of the hair.
In fact, hair that is visible above the surface of the skin is actually dead.
The bulge also provides the insertion point for the arrector pilia tiny band of muscle tissue.
The contraction of these muscles is what causes hairs to stand on end when you get goosebumps.
The hair growth cycle is split up into three phases: anagen, catagen, and telogen.
Here are some more details about each phase.
Anagen
This is the growth phase.
Anagen hairs also vary in size, from long, thick terminal hairs to short, light-colored vellus hairs.
Increased hormones during puberty turn vellus hair (almost colorless) into terminal hair (darker and larger).
Catagen
This is the regression phase.
Over the course of a few weeks, the hair growth rate slows down and the hair follicle shrinks.
The catagen phase lasts two to three weeks.
Telogen
This is the resting phase, which lasts roughly three months.
After a few months, hair stops growing and detaches from the hair follicle.
New hair starts to grow and pushes the old, dead hair out.
During periods of stress, more hair enters thetelogen phaseand begins to fall out.
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