Hair

What is the primary composition of hair?

Hair is composed mainly of keratin.

What are the three layers of the hair shaft?

Cuticle, Cortex, and Medulla.

What is the function of the cuticle in hair?

The cuticle is the outermost layer that protects inner layers and provides shine.

What does the cortex of the hair provide?

The cortex provides strength and color to hair and contains chains of keratin and melanin.

What is unique about the medulla?

The medulla is the innermost layer that is absent in finer hair and its function is not well understood.

What is a hair root?

The hair root is embedded in the hair follicle and contains living cells that divide and grow to produce new hair.

What does the hair follicle do?

The hair follicle is a sheath that surrounds the hair root and contains specialized structures like the hair bulb.

What occurs in the anagen phase of hair growth?

The anagen phase is the active growth phase where cells in the hair bulb rapidly divide, producing new hair.

How long does the catagen phase last?

The catagen phase lasts about 2 to 3 weeks.

What happens during the telogen phase?

During the telogen phase, hair is not growing, the hair follicle is inactive, and hair may fall out.

What is terminal hair?

Terminal hair is thick, long hair found on the scalp, face (such as beards), and body (such as underarms and pubic regions).

Describe vellus hair.

Vellus hair is fine, short, light-colored hair that covers most of the body and helps regulate body temperature.

What is lanugo?

Lanugo is soft and fine hair that covers a fetus in the womb and sheds before birth.

List a function of hair related to protection.

Hair provides protection to sensitive areas.

What is hirsutism?

Hirsutism is excessive hair growth in women in areas associated with male hair patterns, related to hormonal imbalances.

What disorder is characterized by hair loss in patches?

Alopecia is characterized by hair loss in patches and thinning of hair.

What causes dandruff?

Dandruff is caused by flaking skin often due to an overgrowth of yeast on the scalp.

What are hair shaft disorders?

Hair shaft disorders include brittle hair, split ends, and hair breakage.