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BMS 100 > Fundamental Physiologic Basis of the Dermatologic Exam > Flashcards

Fundamental Physiologic Basis of the Dermatologic Exam Flashcards

1
Q

How is the skin a protective barrier (3)

A
  1. Mechanical, chemical or thermal injuries
  2. Important barrier to infection
  3. Reduces heat, fluid, and electrolyte loss
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2
Q

Functions of skin

A

protective barrier
provides sensory information
limited importance in waste removal and vitamin synthesis (vitamin D)

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3
Q

The skin is the _______ and _______ organ

A

largest and heaviest
- 8 lbs, 1.5 - 2 m2

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4
Q

What are the three layers of the skin

A

Epidermis
Dermis
Subcutaneous

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5
Q

Thickness of the skin will vary depending on the

A

body part/area

example:
Thick – palms and soles
Epidermis is 0.4 – 1.4 mm thick
Thin – everywhere else
Epidermis is 0.075 – 0.15 mm

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6
Q

Epidermal Layers
From outermost to innermost:

A

Stratum corneum
Stratum lucidum (only in thick skin)
Stratum granulosum
Stratum spinosum
Stratum basale

Dermis underneath

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7
Q

the most superficial layer of the epidermis. What is layer size?

A

Stratum Corneum
Layer Size: 15-30 cell layers

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8
Q

function of the Stratum Corneum

A

the most important component of the barrier
Prevents penetration of microbes
Prevents dehydration
Mechanical protection

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9
Q

describe the skin cells found in the Stratum Corneum (most superficial layer)

A

Skin cells here are dead, full of
keratin and filaggrin
- Held together by tight junctions,
desmosomes

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10
Q

__________ helps keratin aggregate
into large macrofibrils

A

Filaggrin helps keratin aggregate
into large macrofibrils

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11
Q

Layer immediately below s. corneum is? What is the layer size?

A

Stratum Lucidum
Layer Size: 3-5 cell layers

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12
Q

Stratum Lucidum is only found where?

A

Only found in thick skin of the
palms, soles, and digits

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13
Q

function of Stratum Lucidum?

A

Function
▪ Protection, similar to s. corneum
▪ These cells are dead, just like the
s. corneum

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14
Q

Layer between the s.
corneum and s. spinosum and layer size

A

Stratum Granulosum

Layer Size
▪ 3-5 cell layers, becoming
compacted and flattened

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15
Q

Function of Stratum Granulosum

A

Function
▪ 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

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16
Q

Layer superficial to the s.basale and layer size

A

Stratum Spinosum

Layer Size
▪ 8-10 cell layers – in most skin this
is the thickest layer
▪ Very thick in thick skin

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17
Q

thickest layer of the epidermis

A

Stratum Spinosum

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18
Q

Function of Stratum Spinosum

A

Function
▪ 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

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19
Q

deepest epidermal layer and layer size

A

Stratum Basale
Layer Size: single layer

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20
Q

what are tonofibrils

A

Thick bundles of keratin

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21
Q

Function of Stratum Basale

A
  • Stem cells divide and give rise
    to all of the layers
  • has Melanocytes:
  • Wide range of sensory
    receptors
  • Resident immune cells (Langerhans cells)
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22
Q

what cells synthesize and distribute melanin to keratinocytes

A

Melanocytes

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23
Q

what layer includes stem cells which divide and give rise to all of the other layers of the epidermis?

A

Stratum Basale

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24
Q

Keratin is a _______ protein

A

fibrous

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25
Q

strong, often flexible long proteins that
have a relatively simple, repeating secondary structure

A

keratin structure
All have many hydrophobic amino acid residues → insoluble
in water

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26
Q

alpha-helical protein with many levels of
structure

A
  • a-keratin
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27
Q

Two strands coiled of a-keratin around each other

A

coiled coil
The two strands interact with each other at sites of hydrophobic amino acid residues

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28
Q

hydrophobic amino acids include:

A

Rich in alanine, valine, leucine, isoleucine, methionine, phenylalanine (all hydrophobic)

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29
Q

keratine structure: long chains of two coiled coils

A

long chains of two coiled coils

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30
Q

two long chains of protofilaments

A

Protofibril

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31
Q

Structure of tonofibrils

A

4 protofibrils

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32
Q

structure of macrofibrils

A

many microfibrils, filaggrin helps the formation

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33
Q

Keratin is held together by ______ and varying numbers of ________ bonds

A

H-bonds and disulphide

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34
Q

“Hardness” of keratin depends on the number of _________

A

disulphide bonds

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35
Q

Dermal Layers From outermost to
innermost:

A

Papillary Layer
Reticular Layer

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36
Q

________ keratin is “just keratin” with no filaggrin, phospholipids

A

Hard

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37
Q

what are two examples of hard keratin or “just keratin”

A

Hair, nails

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38
Q

The alpha-helix is a _____-handed coil, coiled-coil _____-handed

A

The alpha-helix is a right-handed coil, coiled-coil left-handed

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39
Q

what type of CT is in the Papillary Layer? What type of collagen does it include?

A

Loose CT
▪ fine elastic fibers, type III and type I collagen

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40
Q

what type of CT is in the Reticular Layer? What type of collagen does it include?

A
  • Dense irregular CT - type I collagen and elastic fibers
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41
Q

the papillary layer interlocks with ______ and _______

A

Interlocks dermis and epidermis
▪ Papilla = “fingers”
▪ Dermal papillae are
vascularized
▪ Also contains sensory
receptors

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42
Q

What does the reticular layer house?

A

▪ Hair follicles
▪ Nerves, arteries, veins, and
lymphatics
▪ Sebaceous and sudoriferous
(sweat) glands
▪ Some adipose tissue
▪ Smooth muscle cells
▪ Some sensory receptor

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43
Q

what types of collagen are fibril-forming
collagens

A

Type I, II, and III

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44
Q

what is the thicket layer of the skin (hint: usually thickest over the back 4mm)

A

Reticular Layer

45
Q

collagen binds to ______ to keep the skin moist

A

water

46
Q

_____ collagen forms 90% of the body’s collagen, and has the most structural strength

A

▪ Type I

47
Q

many cells produce collagens – in the dermis, which cell produces collagen?

A

it is the fibroblast

48
Q

Collagen is a “coiled-coil” structure as well,
but is not an

A

a-helix

49
Q

tropocollagen

A

Three collagen a-chains (themselves twisted) are coiled around each other
- not really a coil, more parts locking into each other

50
Q

The tight “twisting” of the -chains is
accomplished by a

A

unique amino acid sequence

51
Q

Amino acid sequence of collagen fibres

A

Gly-X-Y
glycine is the smallest- they form kinks that are able to fit in to each other and pack tightly

Often “X” is proline (but not always)
Often “Y” is hydroxyproline (but not always)

52
Q

which vitamin is crucial to collagen formation and crosslinking of hydroxylated a.a.s

A

vitamin C

53
Q

__________ produce tropocollagen fibres that have some degree of hydroxylation and glycosylation that are secreted into the ECM

A

Fibroblasts (or other cells)

54
Q

Outside of the cell, the tropocollagen molecules are assembled into

A

fibrils and fibres
These fibrils and fibres are also linked to proteoglycans and glycoproteins

55
Q

what can be described as An epidermal in-growth into the dermis (invagination) that builds a long structure formed from hard
keratin

A

A HAIR

56
Q

All hair follicles, although found
in the dermis, are derived from

A

the epidermis
- the epidermis invaginates and comes back out

57
Q

Are there areas of the skin completely
without hair?

A
  • Palms and soles
  • Lips, genital structures (glans penis,
    labia minora, clitoris)
58
Q

Roughly _ million hairs total

A

5

59
Q

The face has a lot of hair – _____
hairs/cm2; most other areas have around ___/cm2

A

600 vs 60

60
Q

What are the three layers of the hair shaft?

A

▪ Medulla
▪ Cortex
▪ Cuticle

61
Q

hair structure: the bulbous part at the base of the follicle

A

the hair bulb

62
Q

how does hair get its colour?

A

Melanocytes in the bulb transfer melanosomes to keratinocytes

63
Q

Part of the hair shaft that is more interior and lightly keratinized

A

Medulla

64
Q

Part of the hair shaft that is filled with hard keratin

A

*Cortex

65
Q

Part of the hair shaft that the structure of the
keratinocytes is more easily seen – look like “tiles” or “shingles”

A
  • Cuticle
66
Q

Technically, not called hair
shaft until it passes beyond the _________

A

epidermis

67
Q

a bundle of smooth muscle cells that pull the shaft into a more erect position

A

Arrector pili

68
Q

how are the arrector pili innervated and where are they found? (which side of the hair root)

A

Innervated by the sympathetic nervous system, found on the same side as the sebaceous gland

69
Q

why does our hair need to be in an erect position?

A

provide a layer to trap heat and add insulation
- THERMOREGULATION

70
Q

the hair root plexus has very ______ mechanoreceptors

A

sensitive
▪ Myelinated nerves
▪ Desensitize rapidly

71
Q

What are the three phases of hair growth

A

Anagen
Catagen
Telogen

72
Q

what hair growth phase does this describe? longer period of mitotic activity and growth

A

Anagen
can take 2-6 years

73
Q

what hair growth phase does this describe? arrested growth and regression of
the hair bulb

A

Catagen
transition phase (1-2 weeks)

74
Q

what hair growth phase does this describe? cellular inactivity, often → hair shedding

A

Telogen
resting phase (5-6 weeks)
dermal popilla separates from follicle = no more nourishment

75
Q

At the beginning of the next anagen phase,
epidermal stem cells produce ________

A

progenitors

76
Q

what do the progenitors give rise to?

A

The progenitors give rise to the matrix of the
new hair bulb

77
Q

estrogen and progesterone help the hair shift into which phase?

A

Anagen – a longer period of mitotic activity
and growth
- causes sudden rapid hair loss after pregnancy due to lower levels of estrogen and progesterone

78
Q

Stem cells are located in the _________ of
the follicle, the external root sheath, near
the attachment points of the arrector pili

A

outer layer

79
Q

Hypodermis/subcutaneous tissue/superficial
fascia is the ______ most layer. It contains _____ areolar and ______ tissue

A

lowermost layer
contains loose areolar and adipose tissue

80
Q

The hypodermis/subcutaneous tissue/superficial fascia is important in …

A

Important in stabilizing the position of the skin in relation to underlying tissues

81
Q

what layer of skin is considered a fat storage area which insulates against excessive heat loss

A

Hypodermis/subcutaneous tissue/superficial
fascia

82
Q

which region of the Hypodermis/
subcutaneous tissue/
superficial fascia contains vessels

A

the superficial region contains vessels

83
Q

What contributes to our skin colouration?

A

hemoglobin
carotene
melanin

84
Q

red blood cells in vasculature below epidermis

A

Hemoglobin
If deoxygenation occurs (hypoxia) then the skin looks relatively “blue” - cyanosis

85
Q

yellow pigment from plants in the diet

A

Carotene

86
Q

pale yellow to black pigment produced by melanocytes

A

Melanin

87
Q

flat lesion greater than 5mm

A

a patch

88
Q

flat lesion less than 5mm

A

a macule

89
Q

flat and raised less than 5mm

A

papule

90
Q

flat and raised greater than 5mm

A

plague

91
Q

Solid Bump (Round-topped, no fluid) less than 5mm

A

Papule

92
Q

Solid Bump (Round-topped, no fluid) greater than 5mm

A

Nodule
round, solid, no fluid in it

93
Q

Serous fluid filled less than 5mm

A

Vesicle

94
Q

Serous fluid filled greater than 5mm

A

Bulla(e)

95
Q

Pus-filled less than 5mm

A

Pustule (cyst)

96
Q

Pus-filled greater than 5mm

A

Abscess or also a cyst
Depends on the structure - has to be epithelial lining

97
Q

any pocket of fluid (infected or not) lined by epithelium

A

cyst

98
Q

a pocket of purulent fluid (bigger than a pustule) – not lined by
epithelium

A

Abscess

99
Q

a defect in the epidermis, down at least to dermis level, usually
due to impairment of healing/re-epithelialization

A

ulcer

100
Q

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)

A

Vascular lesions

101
Q

accumulation or excess shedding of the stratum corneum – can be dry or waxy-feeling

A

scale

102
Q

A chronic inflammatory condition that appears to have an autoimmune basis

A

Psoriasis

Epidermal hyperproliferation – they divide really quickly
- thin stratum granulosa is thin or absent
- enlarged

103
Q

disorder of skin pigmentation. The immune system attacks the cells that produce melanin

A

Vitiligo

104
Q

NK cells and cytotoxic T-cells attack the hair follicle (adaptive immune system) is the pathophysiology of

A

Alopecia areata

105
Q

____ of alopecia is associated with stressful
events

A

20%

106
Q

Gradual conversion of terminal hairs to vellus hairs - inherited. Greatly dependent on androgen exposure over time in men

A

Androgenetic Alopecia

107
Q

Prevalence of Androgenetic Alopecia is men?
at least ___ of women pre-menopause, > __women older than 65

A

Prevalence – 50% of men
at least 13% of women premenopause, > 50% of women older than 65

108
Q

Nonscarring alopecia is characterized by acute-subacute diffuse hair shedding. Caused by metabolic or hormonal stress or by medications

A

Acute Telogen Effluvium
ex. weight loss can = hair loss

109
Q
A

BMS 100 (37 decks)

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