Hair and nails Flashcards
What is the function of ahir
Protection - UV rays, eyelashes
Sensation
Thermoregulation
Communication
What are the different types of hair?
Lanugo - fetal and shed before birth
Terminal - long thick, on scalp, eyebrows
start as vellus, then terminal by androgen stim
Vellus - short, fine, covers body everywhere
What does a hair follicle consist of?
Sebascous glands (infubd)
arrector pili muscle (isthmus)
Hair bulb - fed blood by DERMAL PAPILLA
3 sections
- infundibulum
- isthmus
- bulb
Hair structure
outer cuticle
cortex
medulla
Outline hair growth regulation
Three stages:
1 - Anagen 2-6 years
Growth - 85pc of hair is in this stage
Vascularised as energy intensive
2 - Catagen 2-3 months
Cell division slows aand stops, end of shaft keratinises, dermal papilla moves to muscle - isthmus
3 - Telogen 2-3 weeks
Hair is actively shed leading to next anagen - takes 4-6 weeks
So hair grows out of snc so that not all hair is lost at once
How does keratin become hair?
Keratin - intermiediate filament - macrofibril - crotical cell - added and bundled to make
Why might hairloss occur
Telogen Effluvium, premature cancellation of anogen
Surgical trauma
Stress
What effects do sex hormones have on hair?
Testosterone paradox
- Surge causes vellus to become terminal
- Pubic and axillary first
- Then chest and beard
Male pattern baldness - androgen sensitve hair location - unsure, ask
due to prologned telogen, reduced anagen
What is the function of nails?
Protection - distal fingertip is bare sensitive
Touch
Communication
What is the structure of nails?
Hard keratin, with longitudinal ridging and curvature
Briefly describe anatomy of nail
Germinal matrix is where it grows from
under lunula which is dome
eponychium is skin that ends before lunula
hyponychium is seal under at distal end
How does nail grow?
Grows out due to adhesion from germinal matrix
Top of nail plate made by matrix - distal
