Hair Flashcards
another name for a hair;
Pilus or Pili - plurar of pilus
a slender filament of keratinized cells growing from a tube in the skin called a hair follicle
Hair
Three types of hair
Lanugo - fetus hair
Vellus - pale hair after birth
Terminal - longer (ur hair now)
Structure of the Hair and Follicle:
- Bulb
- Root
- Shaft
bud of vascular connective tissue
encased by bulb
– Only source of nutrition for hair
Dermal papilla
bud of vascular connective tissue
encased by bulb
– Only source of nutrition for hair
Dermal papilla
region of
mitotically active cells
immediately above papilla
- Hair’s growth center
Hair matrix
diagonal tube that extends into dermis and
possibly hypodermis
Follicle
• Derived from dermis but a bit denser
• Surrounds epithelial root sheath
Connective tissue root sheath
smooth muscle attaching follicle to dermis. Contracts to make hair stand on end (goose bumps)
Piloerector muscle
related to cross-sectional shape of hair
Texture
Three stages of hair cycle:
- Anagen - growth stage
- Catagen - degeneration stage
- Telogen - resting stage
thinning of the hair or baldness
Alopecia
hair lost from select regions
Pattern baldness
excessive or undesirable hairiness in areas that
are not usually hairy
Hirsutism
