Dermis and Adnexal Flashcards
1
Q
What is contained within the dermis? (3)
A
blood vessels
nerves
appendageal strutures (hair / glands / etc)
2
Q
what provides the major tensile strength of the skin?
A
the dermis
3
Q
Thickness of the dermis
A
varies by local (1-4 mm)
4
Q
Where does the dermis lie?
A
between the epidermis and sub-cu
5
Q
what are the appendageal structures ?
A
hair
sweat gland
sebaceous gland
vessels and nerves
6
Q
what are the two major zones of the dermis?
A
papillary
reticular
7
Q
papillary dermis -
location?
content?
interlocks with?
A
upper layer of dermis
thin collagen bundles
interlocks with epidermal rete
8
Q
the interlocking of the dermis with the epidermal rete increases (2)
A
strength and surface area
9
Q
reticular dermis
location?
content?
A
deeper layer
thick collagen bundles
visible eslatic fibers
10
Q
what are the three building blocks of the dermis?
A
collagen
elastic fibers
ground substance
11
Q
structure of collagen in the skin ?
A
alpha helical
Gly-X-Y
X = proline
Y = hydroxyproline
12
Q
How many types of collagen are synthesized in the body
A
> 25
13
Q
G-X-Y of collagen
what are X and Y
A
X proline
Y hydroxyproline
14
Q
Which collagen is in greatest abundance in the skin?
A
collagen I
15
Q
what percent of the adult dermis (wt) is collagen I
A
85%
16
Q
which collagen is largest part of fetal dermis
A
III
17
Q
Which collagen makes up the BM
A
IV
18
Q
Which collagen is responsible for anchoring fibrils
A
VII
19
Q
_________________ are characteristic of mature collagen?
A
“pretty” 68nm bands
20
Q
Where is PROcollagen synthesized?
A
within firboblasts
21
Q
What happens to PROcollagen?
A
excreted extracellularly
22
Q
What happens once PROcollagen is excreted extracellularly
A
it is enzymatically cleaved to TROPOcollagen
23
Q
What happens once TROPOcollagen is produced in ECM?
A
It aggregates and becomes crosslinked
24
Q
Cross-linking of Tropo-collagen is dependent on?
A
Vitamin C
25
What results from VitC deficiency
Scurvy
| decreased mature collagen
26
What would we call VitC
Cofactor
27
How long does it take to manifest sign/symptom of VITC deprivation?
1-3 months
28
Key findings of scurvy?
keratotic plugging of hairs
perifollicular hemorrhage
"corkscrew hairs"
hemorrhagic gingivitis
weakened / delayed healing
29
Why does hemorrhage occur in scurvy?
Lack of collagen support for blood vessels leads to rupture and hemorrhage (same for gums)
30
What kind of disease of collagen production would we call scurvy?
acquired
31
What is a congenital problem of collagen disease?
Ehlers Danlos Syndrome
32
Ehlers-Danlos Syndrome
| family of disorders based upon?
erroneous collagen synthesis
mutation at various stages of collagen production
33
Ehlers-Danlos Syndrome - mutations at various stages of collagen production yield findings such as... (4)
hyperextensible skin
hyperextensible joints
fragile blood vessels
poor wound healing
34
What might you be tempted to think Ehlers Danlos is a disorder of?
Elastic fibers! But resist the temptation! It is a disorder of collagen production
35
Gordin's sign
characteristic of EDS - touch tip of tongue to nose
36
Molluscoid pseudotumors
characteristic of EDS
37
Absence of the inferior labial frenulum can often be seen in
EDS
38
```
Elastic fibers - constitution of dermis?
function
size?
distribution?
visualized?
```
minor constituent of dermis
provide resliency
thin fibers (1-3 micro-meter)
intertwined among collagen bundles
special stains are required to visualize (VVG)
39
Our example of acquired disorder of elastic fiber
Solar elastosis
40
Solar elastosis
acquired disorder of elastic fiber
41
solar elastosis visualizing ?
basophilic (blue) material within superficial dermis
42
If we see basophilic material within superficial dermis - this is a histologic clue that we are observing?
Tissue from an older person in sun-exposed skin - Solar elastosis (sun damaged elastic fibers) - we would not expect to see this in children
43
What is an example (We discussed) of an acquired disorder of elastic tissue?
pseudoxanthoma elasticum
| -
44
pseudoxanthoma elasticum is caused by a mutation in?
MDR gene
45
pseudoxanthoma elasticum results in
calcified, brittle elastic fibers
46
which disease is associated wtih
| - plucked chicken skin
pseudoxanthoma elasticum
47
pseudoxanthoma elasticum is associated wtih
skin finding?
system finding?
eye finding?
plucked chicken skin
systemic hypertension - with arterial rupture (particularly eye)
angioid streaks in the retina
48
Ground substance - made up of?
protein-sugar moieties (glycosaminoglycans) - hyaluronic acid and dermatan sulphate
49
what glues together the protein-sugar moeities of the ground substance?
fibronectin
50
what is an acquired disorder of ground substance? stretch
cosmetic hyaluronic acid filler may (Sometimes) represent an acquired disorder of ground substance
51
what congenital problems do we see with ground substance?
none
52
Blood vessels in the epidermis
none
53
where does epidermis get its nutrient / oxygen supply?
depends entirely on the dermis via diffusion
54
Two plexi of skin vessels?
```
superficial plexus (goes in dermal papillary loop)
deep plexus (with perforating arterioles)
```
55
disorders of capillary loops?
dilated, torturous capillaries are noted with diseases with increased epidermal turnover - psoriasis / verruca
56
when do we see dilated capillaries (which recall are in dermis) with epidermal diseases?
diseases with increased epidermal turnover - e.g. psoriasis / verruca (warts)
57
what causes vasculitis
inflammation of capillaries and venules due to immune complexes depositing in small vessel walls
58
immune complexes in vasculitis may result from?
drug hypersensitivity
infection
neoplasm
collagen vascular disease
59
what type of immune reaction is vasculitis of the dermal capillaries?
type III - antibody mediated so will positive coomb
60
What notable finding will we often see with vasculitis?
palpable purpura
61
what is palpable purpura -
combination of inflammation and hemorrhage that manifests frequently with vasculitis of the dermal capillaries - extravasation can also contribute to palpableness :)
62
Nervous tissue of the dermis?
| job?
inform and protect
63
nerves traverse the dermis to end as?
specialized nerve structures (Meissner / Pacinian)
| free nerve endings
64
Two important types of nerve fibers to be aware of?
A and C
65
Type A nerve fibers
| characteristic
heavily myelinated and conduct rapidly
66
Type C nerve fibers characteristic
unmyelinated and conducts slowly
67
Four types of A fibers?
A -alpha --
A - beta
A - gamma
A - delta
68
A-alpha fibers
proprioception and large motor units (largest)
69
A-beta fibers
carries touch
70
A-gamma fibers
spindle organs in teh muscle stretch receptors
71
A-delta fibers
smallest - fast localizing initial component of pain
72
Type C fibers job
convey sensation of diffuse, dull, non-localizing / temp and itch sensations
73
what is itch called?
pruritis
74
4 common causes of itch
Dry skin (xerosis)
Infection (HIV)
Infestation (scabies / lice)
metabolic disorders (renal failure)
75
Meissner's corpuscles
pine-cone like structures located near the DEJ inovlved in fine touch, highest density on the pulps of digits
76
Pacinian Corpuscles
onion like - structures located in the dermis, involved in pressure and vibration - highest in the genitals
77
Adnexal structures (5)
```
hair follicles
eccrine glands
apocrine glands
apoeccrine glandes
sebaceous glands
```
78
Basics of hair
| Types of hair (2)
terminal
| vellus
79
terminal hair
dark / thick / course
80
vellus hair
fine / thin / apigmented
81
Hair follicle anatomy is divided into 3 regions
infundibulum / isthmus / matrical region
| from bottom to top
82
Which fibers are responsible for itch?
Type C fibers
83
Embryologic origin of hair?
Primitive ectodermal germ (PEG)
| Classic induction
84
Embryologic origin of hair - induction?
mesenchyme induces the overlying neuroectoderm --> downward bud with 3 bulges
85
hair gland 3 bulges?
upper - apocrine (+/-)
middle - sebaceous gland
lower - attachment arector pillori
86
How many hairs does the normal scalp contain
>100,000
87
3 cycles of hair
anagen (growth) 85%
telogen (rest) 10-15%
catagen (involution) 1-5%
88
3 cycles of hair and the rule of three?
anagen - 3 years
telogen - 3 months
catagen - 3 weeks or less
89
androgenic (androgenetic) hair loss?
"pattern baldness"
characteristic loss
50% population
conversion of testosterone to DHT results in miniaturization of follicle
90
treatments of hair loss
finasteride (propecia) - selective inhibitor of 5-alpha reductase
- blocks conversion of testosterone to DHT
- works well in prevent loss and "less well" in restoring hair loss IN MEN
Dangerous in women of reproductive age! ?post-menopause
91
Fiansteride and hair loss
| Women?
NO! do not use in women of reproductive age!
| - blocks conversion to T to DHT and seems to help men from losing more
92
What happens to the hair follicle followin finasteride treatement?
follicles go deeper in dermis
93
Sebaceous glands - purpose?
lubricate thick terminal hairs
94
acne pathogenesis
| disease of?
disease of pilosebaceous unit
95
acne is a disease of pilosebaceous unit - there is abnormal?
follicular maturation
96
abnormal follicular maturation in acne causes ?
comedone formation (black-heads / white-heads)
97
acne - following the comedone formation that resulted from abnormal follicular maturation what happens?
the plugged follicular environment allows overgrowth of P acnes
98
What does P acnes do in acne?
P acnes liberates FFAs and or rupture follicles --> later events yield dermal inflammation
99
Holocrine glands -
whole cells are shed and disintegrate, release contents
100
which are quintessential holocrine glands?
sebaceous glands
101
Eccrine glands -
odorless watery sweat glands
102
Eccrine glands are important in -
thermoregulation
103
where are eccrine glands numerous?
forehead - cutaneous lip - palms/soles
104
eccrine glands produce what type of secretions
merocrine
105
what are merocrine secretions?
excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and thence onto a bodily surface or into the lumen
106
innervation of eccrine glands?
sympathetic - but use ACh
107
Are eccrine glands derived from primitive ectodermal germ?
No!
108
Which glands are derived from PEG (primitive ectodermal germ?)
Upper = apocrine
Middle - sebaceous
Lower - errector pili attachment
109
Eccrine gland anatomy?
sweat production - beginning is located way down between the junction of the dermis and sub-cu --- then travels up long long tube all the way through the dermis and through the epidermis - until it is release onto the skin.
110
2 acquired disorders of sweating?
```
heat shock (classic)
antiperspirants
```
111
Heat shock -
you stop sweating and overheat
112
How do antiperspirants work?
active agent - AlClOH3, selectively soluble
perspiration raise the pH - insoluble precipitates to block sweat duct
washing with soap raises pH - solublel --> duct is unblocked
113
What is miliaria?
prickly heat :) / or sweat gland gets ruptured - sweat goes into dermis where it is not supposed to be and causes prickly heat
blocked sweat ducts
114
miliaria in bambinos -->
febrile
115
what is an acquired disorder of eccrine function?
miliaria
116
are there congenital problems of eccrine function?
anhidrotic ectodermal dysplaisa
117
what is anhidrotic ectodermal dysplaisa?
```
mutation in EDA gene
Aberrant eccrine development
severely decreased sweating
poor temp regulation
other ectodermal problemos - sparse hair / abnormal teeth
```
118
If we see someone come in with decreased sweating / temp regulatory problemos / and other ectodermal problems e.g. hair/teeth... what might we consider?
anhidrotic ectodermal dysplasia
119
apocrine glands are?
outgrowths of the upper bulge of primitive ectodermal germ
120
where are apocrine glands located?
axillary and anogenital area
121
when are apocrine glands functional
usually post puberty
122
specialized apocrine glands (3)
Moll's (eyelid)
cerumen (external auditory canal)
lactation (boobs)
123
how do apocrine glands secrete?
decapitation
124
how is apocrine sweat different than eccrine
stickier (sialomucin)
125
odor of apocrine sweat?
initially odorless but flora of normal skin make smelly
126
apoeccrine glands =
hybrid sweat glands
| located mainly in axilla
127
apoecrrine glands - likely play role in?
axillary hyperhidrosis
128
apoeccrine glands secrete how much sweat relative to eccrine?
nearly 10x
129
Treatment of hyperhidrosis?
botulinum toxin
130
How does botox treat hyperhidrosis?
block acetylcholine release - upon which secretion is dependent!
