IS: Hair

Question 1

Sparse body hair function:

Answer 1

sense when insects are on the skin before the bite/sting

Question 2

Hair on the scalp guards that head against what?

Answer 2

physical trauma, heat loss, and sunlight

Question 3

Nose hairs filter […] like lint and insects from the air we inhale.

Answer 3

large particles

Question 4

Hair/[…] are flexible strands produced by hair […] and consist of largely of […] keratinized cells.

Answer 4

pili; follicles; dead

Question 5

What are the two characteristics of hard keratin? Are they more dominant than soft keratin?

Answer 5

1. tougher, more durable
2. its individual cells do not flake off

hard is more dominant than soft

Question 6

What are the chief regions of the hair?

Answer 6

1. root

2. shaft

Question 7

Shaft = flat/ribbon like

Answer 7

kinky hair

Question 8

Shaft = oval

Answer 8

silky and wavy

Question 9

Shaft = perfectly round

Answer 9

straight and coarse

Question 10

What are the three concentric layers of kerantinized cells?

Answer 10

1. medulla
2. cortex
3. cuticle

Question 11

Medulla’s core consists of […] cells and […] spaces. The only part of the hair that contains […] (absent in fine hairs).

Answer 11

large; air; soft kertain

Question 12

Where is the cortex? What does it consist of?

Answer 12

bulky layer that surrounds the medulla

consists of layer of flattened cells

Question 13

What is the cuticles arrangement? What is it’s purpose?

Answer 13

a single layer of cells overlapping one another like shingles on a roof

separates neighboring hairs so the hairs does not mat

Question 14

The outermost […] is the most heavily […] part of the hair.

Answer 14

cuticle; kerantinized

Question 15

How are split ends created?

Answer 15

when cuticles wear away at the tip of the hair shaft– allowing keratin fibrils (cortex) and medulla to frizz

Question 16

Hair pigment is made by […] at the […] of the hair follicle.

Answer 16

melanocytes; base

Question 17

What is red hair pigmentation made by?

Answer 17

phenomelanin

Question 18

When melanin production […] and air bubbles replace melanin in the hair […], hair turns […] or white.

Answer 18

decrease; shaft; gray

Question 19

Hair follicles […] from the epidermis into the […] sometimes into the subcutaneous tissue.

Answer 19

fold down; dermis

Question 20

The deep end of a follicle expands to form a …

Answer 20

hair bulb

Question 21

What wraps around each hair bulb? What do they act as?

Answer 21

knot of sensory nerve endings called a hair follicle receptor/root hair plexus

act as sensitive touch receptors

Question 22

Hair papilla:

Answer 22

dermal papillae that protrude into the hair bulb

Question 23

What does papilla contain?

Answer 23

a knot of capillaries that supply nutrients to the growing hair and signals it to grow

Question 24

If the hair papilla is destroyed…

Answer 24

follicle permanently stops producing hair

Question 25

The wall of a hair follicle has two components:

Answer 25

1. dermal component

2. epidermal component

Question 26

What is the dermal component? What does it form?

Answer 26

peripheral connective tissue sheath (fibrous sheath)

forms the external layer of the follicle wall

Question 27

Glassy membrane:

Answer 27

junction of the fibrous sheath and the epithelial root sheath

basement membrane of the follicle epithelium

Question 28

What is the epidermal component?

Answer 28

epithelial root sheath

Question 29

What are the two components of the epithelial root sheath? Define them.

Answer 29

1. external root sheath: direct continuation of the epidermis
2. internal root sheath: derived from the matrix cells

Question 30

Hair […] because cells in the […] of the follicle divide rapidly. This makes up the […].

Answer 30

grows; bulb; hair matrix

Question 31

Division of the hair matrix cells are replenished by […] that migrate down to the […] from a region closer to the skin surface called the […].

Answer 31

stem cells; bulb; hair bulge

Question 32

What muscle cells are associated with each hair follicle?

Answer 32

arrector pili

Question 33

Arrector pili:

Answer 33

“raiser of hair”

tiny, smooth muscles attached to hair follicles– contraction causes the hair to stand upright

Question 34

T/F: The “hair raising” response is very useful to humans. Explain.

Answer 34

false– only animals to retain heat and protect themselves

Question 35

What is the more important role of the arrector pili?

Answer 35

contractions forces sebum out of hair follicles to the skin surface– acts as a lubricant

Question 36

Hairs can be classified as […] or […].

Answer 36

vellus; terminal

Question 37

Where can you find pale/fine vellus hair?

Answer 37

body hair of children and adult females

Question 38

Where can you find coarser, longer terminal hair?

Answer 38

eyebrows, eyelashes, scalp– after puberty also in the axillary and pubic regions

Question 39

Terminal hairs grow in response to the […] effects of […].

Answer 39

stimulating effects; androgens

Question 40

Growth cycles:

Answer 40

active growth phase and resting phase

Question 41

What happens in the resting phase?

Answer 41

the matrix is inactive and the follicle shrinks somewhat

Question 42

By age […] coarse terminal hair is replaced by […] and the hair becomes increasingly […].

Answer 42

60-65; vellus hairs; wispy

Question 43

Male pattern baldness changes the response of…

Answer 43

hair follicles to androgens