MSCT Week 5: Acne and Diseases of the Follicle Flashcards
Follicle Definition
the structure that produces the hair shaft
Basic types of hair shafts
- Vellus hairs
- Terminal hairs
Question 1
~100,000 hair follicles on the scalp
Question 2
~100 hairs
Facts about hair
Areas of skin without hairs
- Glaborous skin
- palms and volar surfaces of fingers
- soles of feet
- mucosal surfaces
Facts about hair loss
hair follicles are immunologically privledged sites
Hair follicle cycle of growth
Hair follicle cycle
Anagen & Catagen phases
Hair follicle cycle
Telogen & Exogen phases
Anagen phase
- the production phase of the follicle
- Estrogens prolong
- Androgens increase growth rate in more dependent follicles
- 85-90% of scalp follicles are in this phase at any one time
Catagen Phase
- Regression of follicle
- less than 1% of scalp follicles at any one time
- a hair follicle in this phase can spend 2-3 weeks regressing
Telogen Phase
Resting phase of follicle
10-15% of scalp follicles at any one time are in this phase
A follicle resting in this phase can retain a hair shaft for up to 3 months
Exogen Phase
- Shedding of the hair shaft
- actually occurs in early part of anagen phase as the follicle starts to regenerate and grow a new hair shaft
- Involves not only a mechanical displacement of old hair shaft by new hair shaft but a proteolytic process freeing the shaft from the follicle
- 100-150 hairs shed per day
Question 3
Around 20 cycles per lifetime
Question 4
80-85%
Acne epidemiology/associations/long-term effects
Acne Who is more likely to get acne?
Question 5
Blockage of the pilosebaceous unit with keratin debris
Acne Pathogenesis
4 steps
Acne Causative agent
Propionibacterium acnes
Question 6
All of the above
Acne Triggers
6 listed