SKIN Flashcards
1
Q
7 functions of skin
A
- barrier
- immunological
- homeostatic
- sensory
- endocrine
- excretory
- drug delivery
2
Q
how many layers of skin
A
2: epidermis and dermis
3
Q
how many layers in epidermis
A
4 or 5
4
Q
classify the epidermal epithelium
A
keratinized stratified squamous
5
Q
where is thick skin found
A
palms, soles
6
Q
T or F: thick skin is always hairless
A
T
7
Q
2 layers of dermis
A
papillary, reticular
8
Q
CT type in papillary layer
A
loose CT
9
Q
CT type in reticular layer of dermis
A
dense IR CT
10
Q
range of thickness of skin
A
< 1mm to > 5mm
11
Q
T or F: skin is continuous with mucous membranes
A
T i.e nasal cavity
12
Q
layer underneath dermis
A
subcutaneous layer / hypodermis (NOT SKIN)
13
Q
What is the camper’s fascia
A
hypodermis (aka superficial fascia)
14
Q
in thick skin, which layer changes width?
A
epidermis
15
Q
if include dermis, where is the thickest skin in your body
A
back
16
Q
which epidermis layer is in thick skin, but not thin skin
A
stratum lucidum
17
Q
name the 5 layers of the epidermis from superficial to deep
A
(Stratum): corneum, lucidum, granulosum, spinosum, basale/germinativum (“Come Let’s Get Sun Burnt”)
18
Q
is there a basement membrane in skin?
A
yes, separates epidermis from dermis
19
Q
how many cells thick is the stratum basale
A
1
20
Q
what layer of skin has the dead cells
A
corneum
21
Q
predominant cell type in epidermis
A
keratinocyte
22
Q
function of keratinocyte
A
produce keratin (waterproof barrier)
23
Q
merkel cells: what layer and what type of skin
A
germinativum/basale ; hairless skin
24
Q
what kind of protein is keratin
A
intermediate filament
25
inside vesicles of merkel cells
neuroactive chemicals
26
what causes merkel cells to release their vesicles
touch
27
what is the result of merkel cells vesicle release
stimulation of afferent nerve endings
28
merkel cells = _____ receptor
touch
29
what epidermal layer has langerhans cells
spinosum
30
what body locations have langerhans cells in their epidermis
keratinized skin, mucous membranes, superficial lymph nodes
31
what epidermis layers contain melanocytes
basale, but some melanocytes and their cell processes extend into spinosum
32
ratio of melanocyte: keratinocyte in s. basale
1:4 -1:10
33
function of melanocytes
produce melanin, package into melanosomes
34
what is pigment donation
melanocytes give melanosomes to keratinocytes
35
where do keratinocytes store melanosomes? why?
"supranuclear"; above their nucleus; shield from UV radiation
36
fate of melanosomes in keratinocytes
degradation by lysosomes
37
T or F: some body parts have more melanocytes
true; adaptation
38
what does tanning do to melanocytes
more active; NOT MORE IN NUMBER
39
sunburn = _____
inflammation
40
keratin produced on ____ _________
free ribosomes (protein stays in cell)
41
keratin intermediate filaments (cytoskeleton) are called
tonofilaments
42
what types of cell junctions connect keratin
desmosomes (connect adjacent cells), hemidesmosomes (connect cell to BM)
43
T or F: melanocytes have pale cytoplasm
T; surprisingly
44
T or F: epidermis has no blood supply
T
45
why does s. spinosum look "spiky"
tissue processing; cells shrink when dehydrated , but desmosomes stay in tact
46
what is produced in s. spinosum on free ribosomes
keratinohyalin ; have IF-associated proteins
47
what forms on RER in s. spinosum
lamellar granules (pro-barrier lipids)
48
what 2 types of granules made in s. spinosum
keratinohyalin, lamellar
49
in what layer are lamellar granules released
granulosum
50
what happens at junction of s. granulosum and s. corneum
granulocytes (keratinocytes in s. granulosum) converted to cornfield cells
51
cell shape in basal layer of epidermis
cuboidal
52
how long does it take for cells to become cornfield in s granulosum
2-6 hours
53
T or F: cells in s. granulosum have nuclei, organelles
T, until cornified
54
keratinization in s. granulosum produces ____ ______
soft keratin
55
what do the keratinohyalin granules do in granulosum
IF-associated proteins promote keratin filaments -> tonofibrils & desmosomes (maintain adhesion)
56
3 cellular changes in s. granulosum
breakdown of nucleus & other organelles,
cell membrane thickens
acidification of cytoplasm
57
what holds cells together after s. granulosum
desmosomes
58
some people consider s. lucidum component of s ____
corneum
59
s. corneum consists of ____keratin
soft
60
pH in s. corneum
low
61
how does pH contribute to shed
pH dependent enzymes break down desmosomes, keratinocytes shed
62
how long do cells stay in s. corneum
2 weeks
63
where is hard keratin
nails, hair
64
T or F: keratin prevents 100% of water loss
F; some evaporation; insensible perspiration (loss of fluid, not through glands)
65
in thick skin, how long does it take from basal to shed keratinocyte?
4-6 weeks
66
how does blood affect skin colour
BV density, colour of blood
67
carotene is precursor for _____ _
vitamin A
68
where does carotene accumulate
keratinocytes, adipocytes
69
what happens if you eat too many carrots or squash
carotene => orange-is tinge to skin
70
T or F: darker-skinned humans have more melanocytes
F; dark skin = more active melanocytes -> more melanin (like tanning)
71
eumelanin ->
dark
72
pheomelanin
yellow/red
73
what 2 features of skin increase epidermal-dermal surface area
epidermal ridges, dermal papillae
74
what does thick skin have to increase SA between dermis and epidermis
dermal ridges (fingerprints)
75
term for contact between epidermal ridges and dermal papillae
interdigitation
76
purpose of increasing SA between dermis and epidermis
epidermis = avascular; depends on diffusion to and from dermis (nutrients, gases, waste removal)
77
function of dermal ridges
palms and soles endure greatest friction; want to bind epidermis and dermis tightly
78
CT of papillary dermis
loose CT
79
CT of reticular dermis
dense irregular CT
80
what layer of skin made into leather
reticular dermis
81
what 2 layers is cutaneous plexus between
dermis and hypodermis (like barrier between cutaneous (skin) and subcutaneous)
82
where is sub papillary plexus
under papillary of dermis
83
what BV control superficial blood supply
AV anastomoses from cutaneous -> subpapillary
84
2 types of BV plexus in dermis
cutaneous and subpapillary
85
what BV in dermal papillae
capillary loops
86
what type of innervation in dermis
sympathetic ONLY (think: scared cat -> arrector pili -> hair up)
87
3 things innervated in skin
arrector pili
vascular smooth muscle
glands
88
CT of hypodermis/ superficial fascia
loose CT with adipose tissue
89
from centre, state 7 layers of hair
medulla (soft keratin), cortex (hard keratin), cuticle, internal root sheath, external root sheath (e=epidermis, continuous with), glassy membrane (thick BM), dermis-derived CT
90
What determines length of uncut hair
Anagen (growth phase)
91
Why does hair in axillae not grow as long as hair on head
Shorter growth phase (4 months vs 3-6 years)
92
T or F: melanin production decreases with age
T
93
hair follicle is invagination of _____
epithelium
94
what provides attachment for arrector pili muscle
dense CT sheath
95
name for terminal dilation of hair follicle
hair bulb
96
function of dermal papillae (under hair bulb)
provide BVs, nerves for hair
97
what kind of cells in hair matrix
epithelial cells (basal cells, melanocytes)
98
other than soles and palms, what other hairless places in body
glands penis, labia minora, clitoris
99
what epidermal layers involved in hair follicle
basale and spinosum
100
what layer produces the sheath around the hair follicle
CT dermis
