Dermal Structure and Disease Flashcards
1
Q
Term used to describe the admixture of collagen fibers, elastic fibers, and ground substance of which are all synthesized by dermal fibroblasts
A
dermal matrix
2
Q
interlocking of epidermis and dermis
A
dermoepidermal junction
3
Q
downward projection of epidermis
A
epidermal rete
4
Q
interlocking dermoepidermal junction (2 functions)
A
increased sa
increased strength adherence
5
Q
provides the tensile strength of the skin
A
collagen
6
Q
comprises 85% wt of adult dermis
A
collagen I
7
Q
procollagen is synethesized
A
intracellulary within fibroblasts
8
Q
procollagen consists of
A
three separate chains of proteins arranged in an alpha helical structure
9
Q
characteristic pattern of procollagen
A
striations with 68nm intervals
10
Q
collagen chain repeating unit
A
Gly X Y
X = proline
Y = hydroxyproline
11
Q
once the collagen proteins are synthesized, what happens?
A
they are secreted and assembled into collagen fibrils extracellularly
12
Q
cofactor required for collagen fibril assembly
A
VitC (Ascorbic acid)
13
Q
Acquired abnormality in collagen production
A
scurvy (vit-c deficiency)
- poor wound healing
- poor hair growth
- fragile blood vessels
- teeth fall out
14
Q
congenital abnormailties in collagen production?
A
ehlers danlos
15
Q
4 clinical features of ehlers danlos
A
skin hyperextensibility
joint hypermobility
tissue fragility
poor wound healing
16
Q
Genetic defect –> disordered collagen production
A
ehlers danlos
17
Q
provide skin with tensile strenght
A
collagen
18
Q
provide skin with resliency
A
elastic fibers
19
Q
what do collagen fibers look like under microscope
A
large eosinophilic (pink) bundles
20
Q
elastic fibers under microscope
A
agryophilic (silver loving)
21
Q
acquired eslatic fiber disorder
A
solar elastosis
22
Q
solar elastosis - cause
A
accumulation of significant sun damage over lifetime –> degeneration of elastic fibers –> clump / aggregate
23
Q
sun-damage elastic fibers in solar elastosis under microscope?
A
basophilic - important when evaluating for sun induced neoplasms
24
Q
inherited (Genetic) elastin disorders?
A
PXE
Pseudoxanthoma elasticum
25
Pseudoxanthoma elasticum =
genetic disorder effecting elastin
| caused by mutation in gene encoding for part of the "multidrug resistance complex"
26
What happens in Pseudoxanthoma elasticum
elastic fibers of the dermis become enlarged, tangled, and calcified resulting in a characteristic purple blue color
27
clinical sign of PXE
Plucked chicken apperence of skin in flexural areas -
elastic fibers of the blood vessels are also damaged leading to hypertension adn bleeding disorders, particularly of the eye
28
ground substance is composed of?
glycosaminoglycans: hyaluronic acid / dermatan sulphate
fibronectins
29
function of ground substance
sponge - helps facilitate nourishment via diffusion - water based environment
30
ground substance life cycle
in contrast to collagen fibers which are renewed mostly when necessary, the ground substance is constantly being destroyed by enzymes and renew via production from friboblasts
31
enzyme that eats ground substance
hyaluronidase
32
why is hyaluronic acid (restylane) such a good filler
it is a natural substance that is already present in teh skin and it does not engender an immune response while absorbing a tremendous amount of water
33
two levels of vasculature of dermis
superficial
| deep
34
important function of cutaneous vascular system
| 3
wound healing
control of homeostasis (Temp)
modulation of inflammation
35
wound healing of cutaneous vasculature - the _________, a single cell lining on the innermost surface of blood vessels elaborate important cytokines including ________________
endothelium
endothelial growth factor
36
the cutaneous vasculature
homeostasis - via a structure called_______________, a smooth muscle derived valve-like structure, blood may be directed twoard teh skin during overheating or away during hypothermia
Sucquet-Hoyer canal
37
cutaneous vasculature - modulation of inflammation - via the expression of _____________________ white blood cells begin the process of first adhering and rolling, and second diapedesis, so that they may exit the vasculature to fight infection in the skin and soft tissue
ICAMs
38
The actual capillary structures of the skin are contained in the
uppermost portion of the papillary dermis - a portion sometimes called the suprapapillary plate
39
Auspitz sign
when thickened scaled of psoriasis are forcefully removed, pinpoint bleeding is noted in the area of removal
40
The presence of central thrombosed capillar loops is reassuring that a neoplasm is in fact a
verruca - wart (viral neoplasm)
41
leukocytocalstic vasculitis
common disease involving post capillary venules
42
what happens in leukocytoclastic vasculitis
formation of immune complexes - (most commonly due to strep) - precipitation of complexes in the walls of vessels leads to disease
43
What type of immune reaction is leukocytoclastic vasculitis
TYPE III
| Gel and Coombs
44
What happens as a result of immune complex precipitation in leukocytoclastic vasculitis
leads to inflammation - neutorphils attach to vessel wall and degranulate leading to damage and extravasation of RBCs into the dermis
45
in leukocytoclastic vasculitis what is it called when there is the fibrinoid deposition in the vessel walls with infiltrating neutrophils and neutrophil debris?
leukocytoclasia :)
46
Clinically vasculitis manifests as
palpable purpura
47
why is palpable purpura palpable
inflammation
48
what is purpura purpuric?
extravasation of RBCs
49
Is palpable purpura blanchable
no because the RBCs have extravasated
50
example of Type I skin reaction
IgE - immediate
| urticaria (Hives)
51
example of Type II skin reaction
anitbody mediated - bullous pemphigoid
52
example of Type III skin reaction
```
immune complex mediated
leukocytoclastic vasculitis (palpable purpura)
```
53
example of Type IV skin reaction
delayed type hypersensitive
| - allergic contact dermatitis - nickel allergy
54
where do free nerve endings traverse?
pass through the upper dermis to terminate at the dermoepidermal junction
55
free nerve endings sense
pain and itch
56
itch originates where
free nerve endings at dermoepidermal junction
57
where is itch conducted
centripetally by affarent nerves
58
affarent nerves in pruritus
unmyelinated C fibers with slow conduction rate
59
after entering the spinal cord, the primary affarent nerves of the skin synapse with
secondary neurons whose axons cross to the opposite side of the body and travel cephalide
60
are itch and pain the same sensory modality
no - regardless of the fact that local anesthesia can abolish both - receptors and transmission apparti are thought to differ
61
Pine cone receptors
Meissners - fine touch and tactile discrimination
62
meissner's corpuscles are in highest concentration
digital aspects of the digits
63
onion receptors :)
pacinian corpuscles
| pressure and virbatory
64
terminal hairs begin
deep in the dermal / sub-cu junction
65
vellus hairs -
fine apigmented hairs that begin higher in the dermis
66
small smooth msucle which when activated by teh ANS brings hair into a more erect psoition
arrector pilli
67
secretes sebum onto hair and idirectly onto skin
sebaceous gland
68
local of sebaceous glands
face neck chest upper back
69
divide the hair follicle into thirds
top - infundibulum
middle - isthmus (sebaceous duct to arrector pilli insertion)
bottom - matrical (bottom)
70
follicular unit is derived from
primitive ectodermal germ PEG
71
development of the PEG is an example of _____________ via the _____________
induction via
underlying mesenchyme, which will become the dermal papillae of the hair inducing formation of the PEG in the overlying fetal skin
72
BULGES OF THE PEG
Upper
Middle
Loower
Lower - attachment for arrector pilli
Middle - sebaceous gland
Upper - apocrine gland (axillae, groin)
73
adult scalp # hairs
100,000
74
anagen
85% adult hairs (growth phase)
75
telogen
10-15% adult hairs (resting)
76
catagen
1-5% transition phase between anagen and telogen
77
scalp hairs are what kind
terminal hairs
78
andronergic alopecia
hairs become miniaturized, finer and lie higher in the dermis - resemble vellus hairs
79
frequency of alopecia
50% both sexes
80
important in promoting change from terminal to vellus hair in alopecia?
converstion of T to 5-DHT
81
Medicne for male alopecia?
finasteride - a 5-alpha reductase inhibitor
82
what does minoxidil do?
drug for alopecia that promotes the anagen phase of hair growth - both sexes
83
oil secreting glands?
sebaceous
84
Sebaceous glands secrete via?
holocrine
85
holocrine secretion
involves entire sebocyte
86
requsite to sebum secretion?
sex hormones
87
are sebaceous glands innervated by ANS?
No!
88
Medicine that decreases sebum production
isotretinoin (Accutane)
89
Acne =
ubiquitous disorder of the pilosebaceous unit - multifactorial
90
brief cause of acne
plugging of the ostia of the pilosebaceous unit by hyperkeratotic debris leads to accumulation of oil within
91
once the ostia of the pilosebaceous unit is plugged by hyperkeratotic debris --> the accumulation of oil causes?
propionbacteriam acnes to multiply and convert sebum to pro-inflammatory fatty acids
92
what causes characteristic inflammatory zit?
rupturing of the pilosebaceous unit
93
what are blocked pores called?
comedones
94
open comedones?
blackheads
95
closed comedones?
whiteheads
96
general sweat glands =
eccrine
97
eccrine sweat gland fx
thermoregulation
98
eccrine sweat glands most numerous where?
forehead, upper cutaneous lip, palms/soles
99
eccrine secretion type?
merocrine -
100
merocrine secretion?
The gland releases its product and no part of the gland is lost or damaged (compare holocrine and apocrine). The term eccrine is specifically used to designate merocrine secretions from sweat glands (eccrine sweat glands).
101
eccrine glands develop from?
eccrine germ
102
three main components of eccrine gland?
coiled secretory portion deep in the dermis
intradermal ducts (coiled and straight duct)
intraepidermal portion (acrosyringium)
103
what portion of the ANS mediates sweating?
sympathetic
104
sweating is triggered via?
acetylcholine secretion
105
why do drugs that increase acetylcholine levels (neostigmine, physostigmine, organophosphate based peticides) result in increased sweating despite a parasympathetic response systemically?
they increase acetylcholine levels - which stimulates sweating
106
what does atropine poisoning (a drug which has anticholinergic activity) result in?
warm / flushed / but anhidrotic patient
107
apocrine glands are outgrowths of the?
upper bulge of the pirmitive ectoderm
108
apocrine glands are located primarily?
axillary and anogenital area
109
speiclized variants of apocrine glands?
Moll's --> eyelids
Cerumen --> external auditory
Lactation --> boobs
110
apocrine glands respond mainly to _____________ stimuli
sympathetic adrenergic
111
apocrine gland anatomy
coiled portion deep in dermis
straight duct traverse dermis and empties into hair follicle
contractile myoepithelial cells surround the coiled gland - the straight duct runs from the coiled gland to the hair follicle
112
predominant form of apocrine secretion?
decapitation -
113
decapitation secretion?
portion of the secretory cell cytoplasm pinches off and enters the lumen
114
apocrine sweat? odor
initally odorless until contacts normal bacterial flora and odor develops
115
chromohidrosis
colored sweat
disorder of apocrine glands
lipofuscin pigment is responsible for colored sweat
116
what accounts for lipofuscin color in chromohidrosis?
various oxidative states - yellow / green / blue / black
117
treatment for chromohidrosis?
none
118
apoeccrine glands -
hybrid sweat glands found chiefly in axilla
119
anatomy of apoeccrine?
small diameter portion - similar to eccrine
larger diameter portion - similar to apocrine
120
apoeccrine glands respond to?
cholinergic - similar to eccrine
121
where to apoeccrine glands empty
directly on to skin surface
122
relative sweat secretion of apoeccrine glands vs eccrine?
secrete nearly ten times as much sweat as eccrine
123
hyperhidrosis involves which glands?
eccrine and or apoeccrine
124
new and exciting treatment for hyperhidrosis?
BOTOX
| blocks the release of acetylcholine - thereby blocking the stimulus for sweat production
125
apocrine glands before puberty
small and nonfunctional
126
Caused by a mutation in EDA gene
severely decreased sweating
poor temp regulation
sparse hair / abnormal teeth
diagnosis?
anhidrotic ectodermal dysplasia
127
acquired disorder of eccrine function?
miliaria
128
anhidrotic ectodermal dysplasia is what type of disorder of eccrine function?
congenital
| in contrast to miliaria - which is acquired
129
blocked sweat ducts
prickly heat
febrile babies
sweat in dermis :(
what is your diagnosis?
miliaria -
acquired disorder of eccrine function
130
classic acquired disorder of sweating?
heat shock
131
are eccrine glands from PEG
NO!
| from eccrine germ (unique)
132
Quintessentail holocrine glands?
sebaceous
133
What determines which of the three cycles of hair growth hairs are in?
randomly engaged in 1/3 cycles
134
cycles of hair growth rule of three/
anagen - 3 years
telogen - 3 months
catagen - 3 weeks
135
catagen =
involution
136
itch =
pruritis
137
4 commons causes of itch
dry skin (xerosis)
infection (HIV)
infestation (scabies / lice)
metabolic disorders (renal failure)
138
two important types of nerve fibers to be aware of?
Type A - heavily myelinated - conduct rapidly
Type C - unmyelinate - conduct slowly
139
Typa A alpha fibers?
propioception - large motor units
| largest
140
Type A beta fibers
carries touch
141
Type A gamma fibers
spindle organs in the muscle stretch receptor
142
Type A delta fibers
fast localizing initial component of pain
143
Type C fibers
convey sensation of diffuse, dull, non-localized
| temperature and itch
144
common causes of vasculitis?
drug hypersensitivity
infection
neoplastic disorder
collagen vascular disease
145
congenital problemos of ground substance/
none
146
ground substance is glued together with
fibronectins
147
glycosaminoglycans of ground substance
hyaluronic acid
| dermatan sulphate
148
net result of pseudoxanthoma elasticum?
calcified brittle elastic fibers
plucked chicken skin
systemic hypertension
arterial rupture (particularly eye)
149
acquired disorder of elastic tissue?
solar elastosis
150
congenital disorder of elastic tissue
pseudoxanthoma elasticum
151
acquired disorder of collagen?
Scurvy
152
congential disorder of collagen?
EDS
153
Characteristic clinical signs of scurvy?
corkscrew hairs with perifollicular hemorrhage
keratotic plugging of hairs
hemorrhagic gingivitis
154
why does hemorrhage occur in scurvy?
lack of collage support for blood vessels
155
where is procollagen synthesized
within fibroblasts
