ch 6 pt 2

Question 1

what are the accessory organs of the skin

Answer 1

hair, nails, and cutaneous glands

Question 2

what are hair and nails mostly composed of

Answer 2

mostly composed of dead, keratinized cells

Question 3

what kind of keratin makes up the…

1. stratum corneum of the skin
2. hair and nails

Answer 3

1. stratum corneum is made up of pliable, soft keratin
2. hair and nails are made up of compact, hard keratin
   (tougher and more compact due to numerous cross linkages between keratin molecules)

Question 4

why don’t nails shed off

Answer 4

they are so packed with keratin = super tough and protective and allow us to grip things

Question 5

pilus

Answer 5

another name for a hair

pili= plural

really anything that projects from the surface of the skin

Question 6

If hair covers most of the body, what does hair not cover

Answer 6

does not cover

• palms/soles
• far ends of fingers and toes
• lips, nipples, some areas genitals

Question 7

what can differences in hairness across individuals be due to

Answer 7

mainly due to differences in texture and pigment of hair

Question 8

what are the three types of hair

Answer 8

lanugo
vellus
termnal

Question 9

lanugo

Answer 9

• fine, downy, unpigmented hair
• appears on the fetus in the last 3 months of development
• dries = waxy, stays for 3 hours or up to 3 weeks
• protects from uterine enviro/amnioitic fluid

Question 10

vellus

Answer 10

• fine, pale hair that replaces lanugo by time of birth
• not as pigmented = less melanin
• peach fuzz= ex
• Two-thirds of the hair of women
• One-tenth of the hair of men
• All of hair of children except eyebrows, eyelashes, and hair of the scalp
• can become terminal

Question 11

terminal

Answer 11

• longer, coarser, and more heavily pigmented (more melanin)
• Forms eyebrows, eyelashes, and the hair of the scalp
• After puberty, forms the axillary and pubic hair
• Male facial hair and some of the hair on the trunk and limbs

Question 12

what are the three zones along the length of hair

Answer 12

bulb
root
shaft

Question 13

what is the bulb

Answer 13

swelling at the base of hair where hair originates in dermis/hypodermis

-has stem cells=keratinocytes= new hair

Question 14

what is the root

Answer 14

the remainder of the hair in the follicle

• aka does not protrude out of skin
• no more cell division

Question 15

what is the shaft

Answer 15

the portion of the hair that is above the skin surface

Question 16

what is the dermal papilla

Answer 16

the bud of vascular connective tissue encased by bulb

-is the only source of nutrition for the hair

Question 17

when looking at a cross section of hair, what are the three layers

Answer 17

medulla
cortex
cuticle

Question 18

what is the medula

Answer 18

core of loosely arranged cells and air spaces

• deepest layer
• active with stem cells= growth in length and diameter

Question 19

cortex

Answer 19

• constitutes the bulk of the hair
• consists of several layers of elongated keratinized cells
• stronger covering over medulla
• similar to stratum granulosa

Question 20

cuticle

Answer 20

composed of multiple layers of very thin, scaly cells that overlap each other

• free edges directed upward
• similar to stratum corneum

Question 21

when getting a perm what happens

Answer 21

perm is alterin the desmosomes of hair bu breaking the bonds between desmosomes and cuticle to then artificially remake new bonds between them= new hair conformation

Question 22

what is a follicle and what does it contain

Answer 22

follicle= diagonal tube that extends into dermis and possibly hypoderms

contains

• epithelial root sheath
• connective tissue root sheath

Question 23

epithelial root sheath

Answer 23

• Extension of the epidermis lying adjacent to hair root

- Widens at deep end into bulge—source of stem cells for follicle growth

Question 24

connective tissue root sheath

Answer 24

• Derived from dermis but a bit denser

- Surrounds epithelial root sheath

Question 25

what are hair receptors

Answer 25

sensory nerve fibers connected to follicles -for fine touch/pain/pressure

Question 26

piloerector muscle

Answer 26

smooth muscle attaching follicle to dermis - contracts to make hair stand on end (goose bumps = scared, cold, sexual arousal)

Question 27

fingernails and toenails are described as

Answer 27

clear, hard derivatives of stratum corneum -composed of thin, dead cells packed with hard keratin

Question 28

what is the function of the nail

Answer 28

-for gripping=counterforce aka Provide a counterforce to enhance sensitivity of fleshy fingertips to tiny objects

Question 29

what is the nail plate and what does it consist of

Answer 29

hard part of the nail consist of: -free edge: overhangs fingertip=white=no blood vessles - nail body: visible attached part of nail - nail root: extends proximally under overlying skin

Question 30

what is the nail bed

Answer 30

skin underlying the nail plate - hyponychium= epidermis of the nail bed - vascular

Question 31

what is the nail matrix

Answer 31

growth zone of thickened stratum basale at proximal end of nail (MIOTIC) -contains the lunule = opaque white crescent at proximal end of nail due to thickness of matrix

Question 32

eponychium

Answer 32

=cuticle -narrow zone of dead skin overhanging proximal end of nail

Question 33

what are the two kinds of sweat glands

Answer 33

apocrine and merocrine

Question 34

what is aprocrine sweat gland

Answer 34

- secretes some water + lots of waste (sim to urine) = milky has lots of FA sweat - located in groin, anal region, axilla, areola, beard area in men (inactive until puberty) - usually attached to terminal hairs - resond to stress and sexual stimulation = secrete pheromones (chems influence behavior of others)

Question 35

merocrine

Answer 35

sweat gland that is most numerous on body (3-4 million) -99% water perspiration = cools body

Question 36

myoepithelial cells

Answer 36

contract in response to stimulation by nervous system - aka secrete more when nervous or stressed - found in both aprocrine and merocrine glands and squeeze perspiration up dcut

Question 37

sebaceous glands

Answer 37

- are flask-shaped and have short ducts opening into hair follicles - Holocrine secretion style - produce Sebum (bodies natural lotion - found on all surfaces

Question 38

sebum

Answer 38

- oily secretion of sebaceous glands - Keeps skin and hair from becoming dry, brittle, and cracked - Lanolin—sheep sebum - contributes to ear wax

Question 39

ceruminous glands

Answer 39

- are coiled, simple tubular glands in external ear canal | - Modified apocrine glands

Question 40

secretions of ceruminous glands and sebaceous glands =

Answer 40

sebum combines with secretions of ceruminous glands and dead epithelial cells to form earwax= cerumen

Question 41

what is cerumen

Answer 41

ear wax - keeps eardum pliable - waterproofs the canal - kills bacteria - makes guard hairs of ears sticky=helps block foreign stuff from entering

Question 42

mammary glands

Answer 42

- milk-producing glands that develop only during pregnancy and lactation - Modified apocrine sweat glands - Rich secretion released through ducts opening at nipple

Question 43

mammy ridges or milk lines

Answer 43

- Two rows of mammary glands in most mammals | - Primates kept only two glands, but a few people have additional nipples along the milk line (polythelia)