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SUGER > Skin > Flashcards

Skin Flashcards

1
Q

Emollients

A

Trap moisture in skin and allow it to rebuild

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2
Q

Humectants

A

Trap moisture and maintains low pH

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3
Q

Functions of skin

A

Barrier to infection
Thermoregulation
Protection against trauma
Protection against UV
Vitamin D synthesis
Regulation of H2O loss

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4
Q

What makes up the epidermis of the skin

A

Stratum corneum
Granular layer
Spinous layer
Basal layer

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5
Q

What makes up the dermis of the skin

A

Glands
Tough connective tissue

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6
Q

Lipid lamellae

A

Water barrier
Allows cells to swell

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7
Q

Natural moisturising factor

A

Maintains pH

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8
Q

Corneocytes

A

Cells of the skin filled with natural moisturising factor

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9
Q

Cornified envelope

A

Surrounds corneocytes

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10
Q

Corneodesomosomes

A

Link corneocytes

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11
Q

What is acne

A

Hypercornification of the skin- blocks the hair follicle entrance

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12
Q

Acne mechanism

A

Hypercornification of the skin- blocks hair follicle entrance
Sebum released from sebaceous glands
Trapped in narrow hair follicles
No oxygen- anaerobic conditions allowing propionic bacteria to multiply
Bacteria breakdown triglycerides into fatty acids

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13
Q

Result of bacteria breaking down triglycerides into fatty acids in skin

A

Increased irritation
Increased inflammation
Attraction of neutrophils

Leads to pus and further inflammation

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14
Q

Effect of low pH on skin

A

Switches off lipid processing enzymes
Inhibits protease inhibitors
Damage to skin layer

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15
Q

pH of skin

A

5.5

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16
Q

Size of skin

A

2m^2

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17
Q

Weight of skin

A

3.6kg

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18
Q

3 layers of skin

A

Epidermis
Dermis
Subcutis

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19
Q

Waterproof barrier- how does the skin act as a barrier

A

Tight junctions between cells in stratum granulosum
Epidermal lipids
Keratin in stratum corneum

Prevents transepidermal water loss

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20
Q

Functions of epidermis

A

Waterproofing
Physical barrier
Immune function
Vitamin D synthesis (endocrine)
UV protection
Thermoregulation

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21
Q

Functions of dermis

A

Thermoregulation
Vitamin D synthesis (endocrine)
Sensory organ

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22
Q

Functions of Subcutis

A

Thermoregulation
Energy reserve
Vitamin D storage
Endocrine organ
Shock absorber

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23
Q

For how long is your skin immersed in water for before going wrinkly

A

Approx 5 mins

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24
Q

What is wrinkly when wet skin mediated by

A

Sympathetic nervous system

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25
Q

Why does the skin wrinkle when wet

A

Due to vasoconstriction in dermis
Improves grip

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26
Q

Skin as a physical barrier

A

Structure of skin helps resist trauma
Stratified epithelium helps resist abrasive forces
Fat in Subcutis acts as a shock absorber

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27
Q

When do serum concentrations of vitamin D peak

A

24-48 hours after exposure

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28
Q

Vitamin D synthesis

A

7-dehydrocholesterol in plasma membranes of epidermal keratinocytes and dermal fibroblasts converted to pre vitamin D3 by UVB

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29
Q

Previtamin D3 (cholecalciferol)

A

Lipid soluble- can be stored in Subcutis adipocytes

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30
Q

15-25 mins whole body exposure produces how much vitamin D

A

10000 IU

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31
Q

Where is 7-dehydrocholesterol stored

A

Plasma membrane of epidermal keratinocytes and dermal fibroblasts

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32
Q

Androgens act on skin as an endocrine organ

A

Act on follicles and sebaceous glands

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33
Q

Thyroid hormones act on what in the skin

A

Keratinocytes
Follicles
Dermal fibroblasts
Sebaceous glands
Eccrine glands

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34
Q

What hormone do dermal fibroblasts produce

A

Insulin-like growth factor binding protein-3 (IGFBP-3)

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35
Q

Where is insulin-like growth factor binding protein-3 (IGFBP-3) synthesised

A

Dermal fibroblasts

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36
Q

Which enzymes convert dehydroepiandrosterone (DHEA) and androstenedione to 5a-dihydrotestosterone

A

17B-hydroxysteroid dehydrogenase
5a-reductase

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37
Q

Where is 17B-hydroxysteriod dehydrogenase found

A

Sebocytes

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38
Q

Where is 5a-reductase found

A

Dermal adipocytes

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39
Q

What are dehydroepiandrosterone (DHEA) and androstenedione converted to in skin

A

5α-dihydrotestosterone

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40
Q

What does skin colour depend on

A

Melanin
Carotenoids
Oxy/deoxyhaemoglobin

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41
Q

3 types of UV light

A

UV -A/B/C

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42
Q

Which types of UV can damage skin

A

UV-A
UV-B

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43
Q

How does UV damage skin

A

Burns
Suppress action of Langerhans cells
Photo-aging
DNA damage (skin cancers)

44
Q

Where is melanin synthesised

A

In melanosomes within melanocytes

45
Q

What is the precursor to melanin

A

Tyrosine

46
Q

How is melanin transported

A

Via dendrites to adjacent keratinocytes

47
Q

Where is melanin stored

A

Keratinocytes

48
Q

2 types of melanin

A

Pheomelanin
Eumelanin

49
Q

Pheomelanin colour

A

Red/yellow

50
Q

Eumelanin colour

A

Brown/black

51
Q

Where is the only site we can produce cholecalciferol (vitamin D3)

A

Skin

52
Q

Which type of melanin is more common in all skin types

A

More eumelanin than Pheomelanin

53
Q

Function of melanin

A

Photoprotective- scatters/filters UV light

54
Q

Which type of melanin does red hair contain high amounts of

A

Pheomelanin

55
Q

Melanin- deleterious effects

A

Prone to photodegredation- may generate ROS
Phoemelanin increases release of histamine
Lots of melanin = less able to utilise UV light to make vitamin D

56
Q

Which type of melanin increases histamine release

A

Pheomelanin

57
Q

How do we respond to sunlight

A

Immediate pigment darkening
Persistent pigment darkening
Delayed tanning

58
Q

Immediate pigment darkening

A

Photooxidation of existing melanin
Redistribution of melanosomes
Occurs within mins and lasts hours/days

59
Q

Which layer of the skin contains melanocytes

A

Stratum basale

60
Q

Persistent pigment darkening (tanning)

A

UVA>UVB
Oxidation of melanin
Occurs within hours, lasts 3-5 days

61
Q

Delayed tanning

A

Increased melanin synthesis
Occurs 2-3 days after UV exposure , maximal at 10-28 days

62
Q

Darker skin has…

A

More melanin (not number of melanocytes)

63
Q

Fitzpatrick skin type

A

6 skin types

64
Q

Fitzpatrick skin type 1

A

Light, pale, white
Very fair- always burns in the sun and never tans

Celtic

65
Q

Fitzpatrick skin type 2

A

White, fair
Fair- burns in the sun and tans with great difficulty

Scandinavian

66
Q

Fitzpatrick skin type 3

A

Medium white to olive
Fair- burns but tans gradually

Caucasian

67
Q

Fitzpatrick skin type 4

A

Olive, mid brown
Medium- hardly ever burns and tans with ease

Mediterranean, Hispanic and some Asian

68
Q

Fitzpatrick skin type 5

A

Brown, dark brown
Light brown- rarely burns and tans profusely

Pakistani and indian

69
Q

Fitzpatrick skin type 6

A

Very dark brown, black
Dark brown- never burns in the sun and is deeply pigmented

African

70
Q

A barrier to infection

A

Properties that render skin a barrier to water also help prevent infection
Range of peptides synthesised by granular layer keratinocytes have anti microbial properties

71
Q

Anti microbial peptides in granular layer keratinocytes

A

Cathelicidin-related anti microbial peptide (LL37)
Beta defensins
S100A7 and S100A8

72
Q

Where are anti microbial peptides produced in skin

A

Granular layer keratinocytes

73
Q

Skin as an immune organ

A

Epidermis = Langerhans cells
Dermis = regulatory T cells
Natural killer cells
Dendritic cells
Macrophages
Mast cells

74
Q

Langerhans cells

A

Antigen-presenting cells
Secrete cytokines

75
Q

Keratinocytes - immunity

A

Secrete cytokines and chemo lines that maintain populations of leukocytes in skin

76
Q

When challenged by pathogens

A

Langerhans cells migrate to dermis and lymph nodes and activate a T-cell response
Keratinocytes proliferate & secrete cytokines
Leucocytes enter skin from blood

77
Q

Merkle cells location

A

Basal epidermis

78
Q

Merkle cell function

A

Light touch

79
Q

Where are pacinian corpuscle located

A

Dermis

80
Q

Where are meissner corpuscles located

A

Dermal-epidermal junction
Dermal papillae

81
Q

Pacinian corpuscle function

A

Pressure/vibration

82
Q

Meissner corpuscle function

A

Touch

83
Q

Thermoregulation

A

Insulation
Heat loss

84
Q

Insulation

A

Subcutaneous fat

85
Q

Temperature range

A

27 degrees- 37 degrees - 42 degrees

86
Q

Heat loss

A

Cutaneous blood flow
Eccrine sweating
Hair

87
Q

Cutaneous blood flow and heat loss

A

Deep vascular plexus (lower reticular dermis)
Superficial vascular plexus (upper reticular dermis)
Loops of blood vessels from superficial plexus extend to reticular dermis

88
Q

What is the most common type of sweat glands

A

Eccrine glands

89
Q

Heat storage equation

A

metabolism – work – evaporation +/- radiation +/- conduction +/- convection

90
Q

What does evaporation depend on

A

Surface area exposed to environment
Temperature and relative humidity of ambient air
Convective air currents

91
Q

Endothermic homeotherms

A

Generate and modulate our own heat through metabolism

92
Q

What controls blood flow in dermal vascular plexuses

A

Autonomic regulation

93
Q

Which type of innervation does hairless skin have

A

Only cholinergic

94
Q

Sympathetic alpha-noradrenergic

A

Vasoconstriction

95
Q

Sympathetic cholinergic

A

Vasodilation

96
Q

Types of innervation in hairy skin

A

Sympathetic alpha-noradrenergic
Sympathetic cholinergic

97
Q

What plays a role in active vasodilation

A

Sympathetic cholinergic nerves
Nitric oxide

98
Q

Number of eccrine sweat glands

A

1.6-4 million

99
Q

Amount of sweat per hour

A

1-3L

100
Q

What is the limiting factor of sweat production

A

Availability of water

101
Q

Piloerection (goosebumps)

A

Arrector pili muscles innervated by sympathetic α1-adrenergic fibres
Contraction raises cutaneous hairs
Likely little significant impact on heat conservation

102
Q

What are arrector pili muscles innervated by

A

Sympathetic alpha1-adrenergic fibres

103
Q

Skin as an energy store

A

Subcutaneous fat acts as an insulator, shock absorber and energy store
White adipose connective tissue

104
Q

What is the normal pH of skin?

A

4.7-5.75

105
Q

What is the normal pH of vagina?

A

3.3-5

106
Q

In which layer of skin will you find Pacinian corpuscles?

A

Dermis

SUGER (17 decks)

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