L2 Hair Flashcards
name and describe the three structures of the hair shaft?
- medulla - centrally located within hair shaft, degenerates to form air filled spaces
- cortex - contains hard keratin, the cylindrical wall of the hair shaft.
- cuticle - outermost layer of shaft, single layer of overlapping flat keratinised cells projecting margins in direction of hair growth
what is the hair follicle?
pit-like invagination of the epidermis that produces hair
what are the 5 structures of the hair follicle?
- internal epithelial root sheath
- external epithelial root sheath
- dermal papilla
- hair matrix
- dermal root sheath
what is the arrector pili muscle? what is its function
muscle - upon contraction causes elevation of hair. function is to maintain body temperature and improve insulation.
what are the two main types of hair follicles?
- primary hair follicle
2. secondary hair follicle
what do primary hair follicles produce?
primary hairs aka guard hairs
true or false: primary hairs posses both sebaceous and sweat glads, and an arrector pili muscle?
TRUE
true or false: secondary hair follicles produce hairs without a medulla?
TRUE
true or false: secondary follicles have a sebaceous, sweat and arrector pili muscle?
FALSE - secondary may have sebaceous gland, but lack sweat and arrector pili muscle
describe the function of tactile hair, does it contain blood and nerves? BONUS POINT: whats the other common name for tactile hair?
- also called: sinus hair
highly adapted for tactile sensitivity
has blood filled sinus and abundantly supplied w/ nerve endings
how many types of fibre produced by sheep? name them, describe their properties.
- 3
1. Kemp: all 3 layers, undesirable, dries badly
2. Heterotype; intermediate
3. true wool; lacks medulla (therefore secondary hair)
is hair growth continuous?
NOPE - grows in phases
what are the phases of hair growth?
- anagen
- catagen
- telogen.
- exogen
describe the processes that occur during hair growth anagen
growing phase: matrix proliferating
describe the processes that occur during hair growth catagen
regressive phase, mitosis and melanogenesise cease, follicle shrinks, dermal papilla shrinks and SEPERATES from hair germ cell
describe the processes that occur during hair growth: telogen
resting phase: hair shaft has CLUBBED BASE, remains anchored to papilla by thin filament in canal
describe the processes that occur during hair growth: exogen
loss of resting hair as a result of new hair growth underneath
