Clin Phys 7 Flashcards
(194 cards)
1
Q
What is the function of the skin?
A
- protective barrier
- key for regulating body temperature
- provides sensory information
- limited importance in waste removal & vitamin synthesis (vitamin D)
2
Q
What is the skin an important barrier for?
A
- mechanical, chemical or thermal injuries
- barrier to infection
- reduces heat, fluid, electrolyte loss
3
Q
T/F: The skin is the largest & heaviest organ
A
True
4
Q
How much does skin weigh?
A
8 lbs
5
Q
What are the layers of the skin?
A
- epidermis
- dermis
- subcutaneous/hypodermis
6
Q
Where is skin thick? Thin?
A
thick: palms and soles (epidermis 0.4-1.4 mm)
thin: everywhere else (epidermis: 0.075-0.15)
7
Q
What is the epidermal layers outermost to innermost?
A
- stratum corneum
- stratum lucidum (only in thick)
- stratum granulosum
- stratum spinosum
- stratum basale
8
Q
What epidermal layer only present in thick skin?
A
stratum lucidum
9
Q
What is the location of the corneum?
A
most superficial layer
10
Q
What is the layer size of the corneum?
A
15-30 cells
11
Q
What is the function of the corneum?
A
- most important component of the barrier
- prevents penetration microbes
- prevents dehydration
- mechanical protection
12
Q
T/F: Skill cells in corneum are dead
A
True
13
Q
What is corneum full of?
A
keratin and flaggrin
14
Q
What is keratin and flaggrin held together by in the corneum?
A
tight junctions, desmosomes
15
Q
What does flaggrin help keratin do?
A
aggregate into large macrofibrils
16
Q
Where is lucidum located?
A
immediatley below corneum
17
Q
What is the layer size of lucidum?
A
3-5 cells
18
Q
T/F: cells in lucidum are dead
A
true
19
Q
What is the function of lucidum?
A
similar to corneum
20
Q
Where is granulosum located?
A
between the corneum and spinosum
21
Q
What is the layer size of granulosum?
A
3-5, flattened and compacted
22
Q
What are the functions of granulosum?
A
- Living cells that are re-organizing keratin and associating it with filaggrin and other proteins
- Lamellar granules – lipid-rich, layered granules that help reduce water loss
23
Q
Where is spinosum located?
A
superficial to basal
24
Q
What is the layer size of spinosum?
A
8-10 cell layers
25
What is the thickest layer of skin?
spinosum
26
What is the function of spinosum?
- Very busy synthesizing keratin, proto-filaggrin, and other proteins
- Eventually keratin becomes 50% of the cell mass of keratinocytes
- Thick bundles of keratin called tonofibrils are linked to desmosomes
27
Where is basale located?
deepest epidermal layer
27
What is the layer size of basale?
single layer
28
What are the functions of basale?
- stem cells divide and give rise to all of the layers
-melaoncytes synthesize and distribute melanin to keratinocytes
- wide range of sensory receptors
- resident immune cells - langerhans cells
29
Which cell layers have living cells?
granulosum,
30
What layer has melanocytes?
basale
31
What is the function of melanocytes?
synthesize and distribute melanin to keratinocytes
32
T/F: Keratin is a fibrous protein
True
33
What is the structure of keratin?
strong, flexible long proteins that have a relatively simple, repeating secondary structure
34
How is keratin insoluble in water?
due to many hydrophobic amino acid residues
35
What are the two layers of alpha-keratin?
- single "strand" protein = alpha helix
- two strands coiled around each other = "coiled coil"
36
Where do the 2 strand interact with each other in a coiled coil?
at amino acid residues
37
What is a protofilament of keratin?
long chains of 2 coiled coils
38
What is a protofibril of keratin?
2 long chains of protofilaments
39
What are 4 protofibrils called?
microfibrils or tonofibrils
40
What are macrofibrils?
many microfibrils
41
What helps with the formation of macrofibrils?
flaggrin
42
T/F: Keratin can be flexible and hard
true
43
What is keratin held together by?
H-Bonds and number of disulphide bones which cross-link individual fibres to each other
44
What does the hardness of keratin depend on?
number of disulphide bones
45
What are rhinoceros horns made of?
18% of residues are cysteines (disulphide bonds) - keratin
46
What side is alpha-helix coiled (keratin)?
right
47
What side is coiled-coil coiled (keratin)?
left
48
What does the coiling of coiled-coil on the left increase (keratin)?
strength
49
What does hard keratin not have?
filaggrin or phospholipids
50
What are examples of hard keratin?
hair, nails
51
What is this?
alpha-helix
52
What is this?
coiled coil
53
What is this?
protofilament
54
What is this?
filament
55
What are the dermal layers from ouermost to innermost?
papillary
reticular
56
T/F: dermal layer has blood vessels
True
57
Which layer of the dermal is the superifical 1/5?
papillary
58
What is papillary layer made of?
loose connective tissue - fine eleastic fibers, type III and type I collagen
59
What does the papillary layer do?
interlocks dermis and epidermis
60
What does papilla mean?
fingers
61
What does the papillary layer contain?
- vascularization
- sensory receptors
62
What is the reticular layer made of?
dense irregular connective tissue - Type I collagen and elastic fibers
63
T/F: Collagen binds to water to keep the skin hydrated
True
64
Which layer of the dermal is the thickest?
reticular
65
What does the reticular layer house?
- hair follicles
- nerves, arteries, veins, lymphatics
- sebaceous & sudoriferous (sweat) glands
- some adipose tissue
- SMC
- some sensory receptors
66
Which types of collagen are fibril-forming?
Type I, II, III
67
Which type of collagen forms 90% of the body's collagen?
Type I
68
Which type of collagen has the most structural strength?
Type I
69
Which cells produce collagen?
many cells in the dermis - fibroblasts
70
Where does final fibril-forming of collagen occur?
extracellular space
71
What structure is collagen?
coiled coil but not alpha-helix
72
What is tropocollagen?
three collagen alpha-chains are coiled around each other
73
How is the tight twisting of alpha chains of collagen accomplished by?
unique amino acid sequence
74
What is the amino acid sequence of collagen?
Gly-X-Y
Often X is proline
Often Y is hydroxyproline
75
The glycine on collagen has a very small what?
R-group
76
What are the structures of hydroxyproline and proline and what does this provide?
kinked - provides twists or kinks in molecule
77
What is the hydroxylated proline in collagen ideal for?
covalent cross-linking
78
What is crucial to collagen formation and cross-linking?
vitamin C
79
How is collagen synthesized?
- fibroblasts produce tropocollagen fibres that have some degree of hydroxylation and glycosylation that are secreted into the ECM
- Outside of the cell, the tropocollagen molecules are assembled into fibrils and fibres
- These fibrils and fibres are also linked to proteoglycans and glycoproteins
80
What is a hair follicle?
an epidermal in-growth into dermis (invagination) that builds a long structure formed from hard keratin (hair)
- specialized keratinocytes
81
Where are hair follicles derived from?
epidermis
82
What areas of skin are completely without hair?
palms, soles, lips, genital structures
83
Which area of skin has the most hair?
face
84
How many hairs in total should a person have?
5 million
85
What is the hair bulb?
bulbous part at the base of the follicle
86
What does the dermal papilla do with reference to hair follicle?
contacts the bulb, supplying capillary network
87
What does the hair bulb hold?
hair matrix (site of active cell division)
88
What do melanocytes in the hair bulb do?
transfer melanosomes to jeratinocytes
89
T/F: With reference to hair bulb, Keratinocytes at the papilla are very similar to the stratum granulosum and spinosum.
True
90
What are the layers of the hair shaft?
medulla
cortex
cuticle
91
Which layer of the hair shaft is lightly keratinized?
medulla
92
Which layer of the hair shaft is filled w/ hard keratin?
cortex
93
Which layer of the hair shaft looks like "tiles" or "shingles"
cuticle
94
T/F: The reason a person has straight or curly hair is due to their cortex
True
95
The hair shaft is not called the hair shaft until?
it passes beyond the epidermis
96
What is arrector pili?
bundle of smooth muscle cells that pull the shaft into a more erect position
97
What is the arrector pili innervated by?
sympathetic nervous system
98
Why does hair need to be in a more erect position?
thermoregulation - when we are cold, to trap heat and regulation
99
What does the hair root plexus contain?
very sensitive mechanoreceptors - myelinated nerves, desensitize rapidly
100
Where is the arrector pili found?
same side of sebaceous gland
101
What are the 3 phases of hair growth?
anagen, catagen, telogen
102
What occurs during the anagen phase of hair growth?
longer period of mitotic activity and growth
103
What occurs during the catagen phase of hair growth?
arrested growth and regression of the hair bulb
104
What occurs during the telogen phase of hair growth?
cellular inactivity (hair shedding)
105
What is produced at the beginning of the anagen phase?
progenitors
106
What do progenitors give rise to?
matrix of new hair bulb
107
When are stem cells located with reference to hair growth?
outer layer of follicle, external root sheath, near attchment points of the arrector pili
108
How long is the anagen phase?
2-6 years
109
How long is the catagen phase?
1-2 weeks
110
How long is the telogen phase?
5-6 weeks
111
What is the lower most layer of the skin?
hypodermis/subcutaneous tissue/superficial fascia
112
What does the hypodermis/subcutaneous tissue/superficial fascia contain?
loose aerolar and adipose tissue
113
What is hypodermis/subcutaneous tissue/superficial fascia important for?
stabilizing the position of the skin in relation to underlying tissues
114
Prolactine/progesterone/estrogen shift hair into what phase while women are pregnant?
anagen
115
After a women gives birth they are then shifted into what phase of hair growth? Causing what?
catagen and telogen causing massive hair loss
116
What is the is hypodermis/subcutaneous tissue/superficial fascia a storage area for? Why?
fat - insulates against excessive heat loss
117
What does the superifical region of the is hypodermis/subcutaneous tissue/superficial fascia contain?
vessels
118
What are 3 components of skin colouration?
hemoglobin, carotene, melanin
119
What is hemoglobin?
red blood vessels in vasculature below epidermis
120
What happens to skin colour if there is deoxygenation? Why?
skin looks "blue" cyanosis due to hypoxia and less hemoglobin
121
What is carotene?
yellow pigment from plants in the diet
122
What is melanin?
pale yellow to black pigment produced by melanocytes
123
What are two important things to note during a skin exam?
morphology & distribution
124
What does morphology encompass with reference to skin exam?
general shape, size, color, appearance
125
What does distribution encompass with reference to skin exam?
is there a pattern? what area of the body does it affect?
126
What is a flat lesion <5mm?
macule
127
What is a flat lesion lesion >5mm called?
patch
128
What is flat + raised <5mm?
papule
129
What is flat + raised lesion >5mm called?
plaque
130
What is a solid bump (round-topped, no fluid) lesion <5mm called?
papule
131
What is a solid bump (round-topped, no fluid) lesion >5mm called?
nodule
132
What is a serous fluid filled lesion <5mm called?
vesicle
133
What is a serous fluid filled lesion >5mm called?
bulla(e)
134
What is a pus-filled lesion <5mm called?
pustule (cyst)
135
What is a pus-filled lesion >5mm called?
abcess or also cyst - depend on structure (has to be epithelial lining)
136
What is a cyst?
any pocket of fluid (infected or not lined by epithelium)
137
What is an abscess?
pocket of purulent fluid (bigger than pustule) - NOT lined by epothelium
138
What stores melanin?
melanosomes
139
What is an ulcer?
a defect in the epidermis, down at least to dermis level, usually due to impairment of healing/re-epithelialization
140
What is a vascular lesion?
include telangiectasias (dilated arterioles, venules that one can see with the naked eye) and hemangiomas (many different types of vessel-rich, red or violet growths)
141
What is a scale?
accumulation or excess shedding of the stratum corneum – can be dry or waxy-feeling.
142
How does atopic dermatitis occur?
Defects in the moisture barrier (filaggrin) and/or tight junctions --> antigens “getting past” the epidermal barrier over and over --> recruitment of immune cells
143
How does atopic dermatitis present?
repetitive episodes of ithcy, erythematous, edematous macular-papular rash
144
Where is atopic dermatitis found?
extensor surfaces, face, scalp
145
What is this showing?
early to late atopic dermatitis (eczema) under the microscope
146
What does (1), (2), and (3) reference in this image?
(1) edema in epidermis
(2) lymphocytes and mast cells
(3) hyperkeratotic skin (from scratching it so much)
147
T/F: Psoriasis is extremely common.
True
148
What is psoriasis?
chronic inflammatory condition that appears to have an autoimmune basis
149
What occurs during psoriasis?
epidermal hyperproliferation - divide quickly
abnormal differentiation of epidermal keratinocytes
150
What is this, describe its attributes?
psoriasis - plaque, thin epidermis, enlarged blood vessels
151
What does psoriasis look like?
morphology: plaque - red base or silvery white scale/ well defined borders
distribution: symmetrical
152
What are common sites of psoriasis?
scalp and extensor surfaces (elbows and knees)
153
What condition is this?
psoriasis
154
What is vitiligo?
disorder of skin pigmentation
155
Why does vitiligo develop?
immune system attacks cells that produce melanin
156
What do melanocytes produce?
melanosomes
157
T/F: Melanosomes can produce their own melanin
True
158
What condition is this?
vitiligo
159
T/F: Abscess is typically infectious
True
160
What does vitiligo look like?
morphology: patch - colourless,
distribution: symmetrical, wide spread
161
What is the prevalence of alopecia areata?
0.1-0.2%
162
What is the lifetime risk of alopecia areata?
1.7%
163
What is the percentage of alopecia areata patients seen by dermatology?
0.7-3%
164
What is the epidemiology of alopecia areata?
M:F = 1:1; affects any age
165
What is the pathophysiology of alopecia?
NK cells & cytotoxic T-cells attack the hair follicle (adaptive immune system)
166
What is ~20% of alopecia areata associated with?
stressful events - severe infection, trauma, severe psychologic stress
167
When is alopecia areata more susceptible to inidviduals?
If they are genetically susceptible
168
What are clinical features of alopecia areata?
patchy hair loss that does not scar - hair will regrow
169
How long does a stressful event predate hair loss by with alopecia areata?
1-6 months
170
T/F: 80-90% of people with alopecia areata have only 1 patch of hair loss
True
171
What areas do alopecia areata often effect?
scalp, beard
172
When does re-growth of alopecia areata tend to occur?
about a year later
173
What is the prevalence of androgenetic alopecia?
50% of men
- at least 13% of women pre-menopause, >50% women older than 65
174
At what age is androgenetic alopecia usually detectable?
Age 40
175
What is the pathophysiology of androgenetic alopecia?
gradual conversion of terminal hairs to vellus hairs - inherited
176
What does androgenetic alopecia development greatly depend on in men?
androgen exposure over time
177
What are clinical features of androgenetic alopecia?
hair loss over the crown for both sexes
- men: posterior and lateral scalp are spared
- women: mid-frontal hair loss/vertex, temporal regions spared; often frontal hair-line preserved/ if rapid check for diseases
178
Do men or women have a larger psychosocial impact due to androgenetic alopecia?
women
179
What condition does this reflect?
androgenetic alopecia
180
What is acute telogen effluvium?
nonscarring alopecia characterized by acute - subacute diffuse hair shedding
181
What causes acute telogen effluvium and when does it occur?
caused by metabolic or hormonal stress or by medications -> hair loss occurs 2-3 months later
182
T/F: The stressor causes anagen hair to enter telogen.
True
183
What is the recovery of acute telogen effluvium?
spontaneous and occurs within 6 months unless background of pattern alopecia is present
184
T/F: There is a chronic form of acute telogen effluvium.
True
185
What does a positive hair pull test indicate?
active hair shedding and can be seen in TE and in active stages of AA or different scarring alopecias
186
What is terminal hair?
thick hair on scalp
187
What is vellus hair?
thin hair seen on body
188
What is the procedure for the hair pull test?
- select 50-60 hairs & hold the bundle close to the scalp b/w the thumb, index finger, & long finger
- firmly pull on the bundle using slow traction as the fingers slide down the hair shaft, avoid a fast and forceful tug
- count the pulled hairs and discard broken hairs
189
T/F: 50% of hairs during hair pluck are in telogen.
False, 25%
190
Where should a hair pull test be done on the head?
performed at vertex, parietal areas, and the occipital area of the scalp
191
If more than 10% of the hairs in each bundle are removed from a scalp area, the hair pull test is considered?
positive - alopecia areata
192
If fewer than 10% are removed, then the hair loss can usually be attributed to?
normal shedding
193
If a test is positive in more than 1 scalp region, the clinician must consider?
telogen effluvium
