Hair Information:
Hair Cross-sectional Anatomy:
The 3 main layers of the include: medulla to the cortex to the cuticle. They are all made from hard keratin
Medulla: It is the innermost layer. It is present in different amounts in different hairs (not consistent).
Cortex: It is the middle layer. It contains pigment and gives the hair its color. It may contain ovoid bodies and cortical fusi.
Cuticle: It is the outermost layer. It is made from overlapping scales. It is very resistant to chemical decomposition.
Hair General Anatomy:
The hair above the surface of the skin is known as the hair shaft. The hair below the surface of the skin is known as the hair root. The hair under the skin is located in a hair follicle which houses the hair root. The arrector pili muscle is attached to the hair follicle. It contracts when you are in fear or when you are cold.
Hair Phases:
Anagen: Anagen is the growth phase for the hair. Hair can last in Anagen for 2-7 years.
Catagen: Catagen is the transitional phase for the hair. It is a 2-3 week phase. It lasts until the hair becomes a club hair. A club is formed when the hair is pushed toward the surface of the skin until it is cut off from the blood supply and hair matrix (site of hair growth).
Telogen: Telogen is the resting phase for the hair (which is a club hair just in case you forgot from about 3 lines ago). 50-100 club hairs are shed from a normal scalp.
Affect of Age on the Hair:
When hair turns white, it is because of decreased melanin production and air bubbles produced in the medulla of the hair.
No comments:
Post a Comment