Dermatology 2 Flashcards
What are the 6 main functions of hair?
- Apocrine sweat
- Social and sexual interaction
- Sebum
- Protection against external factors
- Epithelial and melanocyte stem cells
- Thermoregulation
What are the 2 main types of hair?
Terminal hair
Vellus hair
Where do we find terminal hairs?
Scalp, eyebrows and eyelashes
Where do we find vellus hairs?
Everywhere on the body, except…
- Soles of feet
- Palms of hands
- Mucosal regions of lips and external genitalia.
What are the three components of the hair cycle?
Anagen
Catagen
Telogen
What occurs in anagen?
Occurs right after hair is lost
Generation of a new follicle and with it new hair forms and grows
What occurs in catagen?
Hair regresses due to a restriction of vascular supply.
What occurs in telogen?
Hair is resting and after telogen, hair is lost and the cycle restarts
How much hair at a time is in anagen?
85% of hair, this is because anagen occurs over 2-6 years
How much hair at a time is in catagen?
1% of hair, this is because catagen only lasts fro 3 weeks
How much hair at a time is in telogen?
10-15% of hair as telogens lasts for about 3 months
Describe the structure of hair
Pilosebaceous follicles and sweat glands. Hair follicles are pilosebaceous units. The pockets of epithelium containing hair follicles are continuous with the superficial epidermis and encase the papilla of the dermis at the unit base.
Describe the course of the arrector pili
Extends at the angle from the surface at the dermis to a point in the follicle wall
What are holocrine sebaceous glands?
These are modified sebaceous glands that open into the pilary canal and are found in the axilla therefore are associated with apocrine glands
What are holocrine sebaceous glands associated with?
apocrine sweat glands.