Hair Stucture
Hair is composed of strong structural protein called keratin. This is the same kind of protein that makes up the nails and the outer layer of skin.
Each follicle of hair consists of 3 layers:
2. The middle layer known as the cortex. The cortex provides strength and both the color and the texture of hair.
3. The outermost layer is known as the cuticle. The cuticle is thin and colorless and is also meant for protection of cortex.
Structure of the hair root
Hair root is enclosed within hair follicle, under the skin. At the base of the hair follicle is the dermal papilla. The dermal papilla is feed by the bloodstream which carries nourishment to produce new hair.
Hair Growth Cycle
Hair on the scalp grows about .3-.4 mm/day or about 6 inches per year. Unlike other mammals, hair growth and loss is random and not seasonal or cyclic. At any given time, a random number of hairs will be in various stages of growth and shedding. There are three stages of hair growth:
catagen, telogen, and anagen.
Anagen - Growth Phase
Anagen is the active phase of the hair. The cells in the root of the hair are dividing rapidly. A new hair is formed and pushes the club hair up the follicle and eventually out. During this phase the hair grows about 1 cm every 28 days. Scalp hair stays in this active phase of growth for 2-6 years. Some people have difficulty growing their hair beyond a certain length because they have a short active phase of growth. On the other hand, people with very long hair have a long active phase of growth. The hair on the arms, legs, eyelashes, and eyebrows have a very short active growth phase of about 30-45 days explaining why they are so much shorter than scalp hair.
catagen phase - Transition phase
At the end of the anagen hair is a catagen phase lasts about a week or two during the catagen phase the hair follicle shrinks to about 1 / 6 of normal length. The lower part is destroyed and the dermal papilla breaks, leaving the root.
Telogen Phase - Resting phase
The resting phase follows the catagen phase and normally lasts about 5-6 weeks.Meanwhile, the hair does not grow but remains attached to the follicle while the dermal papilla remains in a resting phase below. Approximately 10-15 percent of all hairs are in this phase at once.
At the end of the telogen phase, hair follicles in the anagen phase again. The dermal papilla and base of the follicle to meet and a new hair begins to form. If the old hair has not yet fallen the new hair pushes the old one on the growth and the cycle begins again.
Tags: Hair images, hair, hair life cycle, hair stages, hair follicles, hair fall,Anagen Phase, Catagen Phase, Telogen Phase.