L2 Hair

Question 1

name and describe the three structures of the hair shaft?

Answer 1

1. medulla - centrally located within hair shaft, degenerates to form air filled spaces
2. cortex - contains hard keratin, the cylindrical wall of the hair shaft.
3. cuticle - outermost layer of shaft, single layer of overlapping flat keratinised cells projecting margins in direction of hair growth

Question 2

what is the hair follicle?

Answer 2

pit-like invagination of the epidermis that produces hair

Question 3

what are the 5 structures of the hair follicle?

Answer 3

1. internal epithelial root sheath
2. external epithelial root sheath
3. dermal papilla
4. hair matrix
5. dermal root sheath

Question 4

what is the arrector pili muscle? what is its function

Answer 4

muscle - upon contraction causes elevation of hair. function is to maintain body temperature and improve insulation.

Question 5

what are the two main types of hair follicles?

Answer 5

1. primary hair follicle

2. secondary hair follicle

Question 6

what do primary hair follicles produce?

Answer 6

primary hairs aka guard hairs

Question 7

true or false: primary hairs posses both sebaceous and sweat glads, and an arrector pili muscle?

Answer 7

TRUE

Question 8

true or false: secondary hair follicles produce hairs without a medulla?

Answer 8

TRUE

Question 9

true or false: secondary follicles have a sebaceous, sweat and arrector pili muscle?

Answer 9

FALSE - secondary may have sebaceous gland, but lack sweat and arrector pili muscle

Question 10

describe the function of tactile hair, does it contain blood and nerves? BONUS POINT: whats the other common name for tactile hair?

Answer 10

• also called: sinus hair
  highly adapted for tactile sensitivity
  has blood filled sinus and abundantly supplied w/ nerve endings

Question 11

how many types of fibre produced by sheep? name them, describe their properties.

Answer 11

• 3
  1. Kemp: all 3 layers, undesirable, dries badly
  2. Heterotype; intermediate
  3. true wool; lacks medulla (therefore secondary hair)

Question 12

is hair growth continuous?

Answer 12

NOPE - grows in phases

Question 13

what are the phases of hair growth?

Answer 13

1. anagen
2. catagen
3. telogen.
4. exogen

Question 14

describe the processes that occur during hair growth anagen

Answer 14

growing phase: matrix proliferating

Question 15

describe the processes that occur during hair growth catagen

Answer 15

regressive phase, mitosis and melanogenesise cease, follicle shrinks, dermal papilla shrinks and SEPERATES from hair germ cell

Question 16

describe the processes that occur during hair growth: telogen

Answer 16

resting phase: hair shaft has CLUBBED BASE, remains anchored to papilla by thin filament in canal

Question 17

describe the processes that occur during hair growth: exogen

Answer 17

loss of resting hair as a result of new hair growth underneath