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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
Why does the skin wrinkle when wet
Due to vasoconstriction in dermis Improves grip
26
Skin as a physical barrier
Structure of skin helps resist trauma Stratified epithelium helps resist abrasive forces Fat in Subcutis acts as a shock absorber
27
When do serum concentrations of vitamin D peak
24-48 hours after exposure
28
Vitamin D synthesis
7-dehydrocholesterol in plasma membranes of epidermal keratinocytes and dermal fibroblasts converted to pre vitamin D3 by UVB
29
Previtamin D3 (cholecalciferol)
Lipid soluble- can be stored in Subcutis adipocytes
30
15-25 mins whole body exposure produces how much vitamin D
10000 IU
31
Where is 7-dehydrocholesterol stored
Plasma membrane of epidermal keratinocytes and dermal fibroblasts
32
Androgens act on skin as an endocrine organ
Act on follicles and sebaceous glands
33
Thyroid hormones act on what in the skin
Keratinocytes Follicles Dermal fibroblasts Sebaceous glands Eccrine glands
34
What hormone do dermal fibroblasts produce
Insulin-like growth factor binding protein-3 (IGFBP-3)
35
Where is insulin-like growth factor binding protein-3 (IGFBP-3) synthesised
Dermal fibroblasts
36
Which enzymes convert dehydroepiandrosterone (DHEA) and androstenedione to 5a-dihydrotestosterone
17B-hydroxysteroid dehydrogenase 5a-reductase
37
Where is 17B-hydroxysteriod dehydrogenase found
Sebocytes
38
Where is 5a-reductase found
Dermal adipocytes
39
What are dehydroepiandrosterone (DHEA) and androstenedione converted to in skin
5α-dihydrotestosterone
40
What does skin colour depend on
Melanin Carotenoids Oxy/deoxyhaemoglobin
41
3 types of UV light
UV -A/B/C
42
Which types of UV can damage skin
UV-A UV-B
43
How does UV damage skin
Burns Suppress action of Langerhans cells Photo-aging DNA damage (skin cancers)
44
Where is melanin synthesised
In melanosomes within melanocytes
45
What is the precursor to melanin
Tyrosine
46
How is melanin transported
Via dendrites to adjacent keratinocytes
47
Where is melanin stored
Keratinocytes
48
2 types of melanin
Pheomelanin Eumelanin
49
Pheomelanin colour
Red/yellow
50
Eumelanin colour
Brown/black
51
Where is the only site we can produce cholecalciferol (vitamin D3)
Skin
52
Which type of melanin is more common in all skin types
More eumelanin than Pheomelanin
53
Function of melanin
Photoprotective- scatters/filters UV light
54
Which type of melanin does red hair contain high amounts of
Pheomelanin
55
Melanin- deleterious effects
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
Which type of melanin increases histamine release
Pheomelanin
57
How do we respond to sunlight
Immediate pigment darkening Persistent pigment darkening Delayed tanning
58
Immediate pigment darkening
Photooxidation of existing melanin Redistribution of melanosomes Occurs within mins and lasts hours/days
59
Which layer of the skin contains melanocytes
Stratum basale
60
Persistent pigment darkening (tanning)
UVA>UVB Oxidation of melanin Occurs within hours, lasts 3-5 days
61
Delayed tanning
Increased melanin synthesis Occurs 2-3 days after UV exposure , maximal at 10-28 days
62
Darker skin has…
More melanin (not number of melanocytes)
63
Fitzpatrick skin type
6 skin types
64
Fitzpatrick skin type 1
Light, pale, white Very fair- always burns in the sun and never tans Celtic
65
Fitzpatrick skin type 2
White, fair Fair- burns in the sun and tans with great difficulty Scandinavian
66
Fitzpatrick skin type 3
Medium white to olive Fair- burns but tans gradually Caucasian
67
Fitzpatrick skin type 4
Olive, mid brown Medium- hardly ever burns and tans with ease Mediterranean, Hispanic and some Asian
68
Fitzpatrick skin type 5
Brown, dark brown Light brown- rarely burns and tans profusely Pakistani and indian
69
Fitzpatrick skin type 6
Very dark brown, black Dark brown- never burns in the sun and is deeply pigmented African
70
A barrier to infection
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
Anti microbial peptides in granular layer keratinocytes
Cathelicidin-related anti microbial peptide (LL37) Beta defensins S100A7 and S100A8
72
Where are anti microbial peptides produced in skin
Granular layer keratinocytes
73
Skin as an immune organ
Epidermis = Langerhans cells Dermis = regulatory T cells Natural killer cells Dendritic cells Macrophages Mast cells
74
Langerhans cells
Antigen-presenting cells Secrete cytokines
75
Keratinocytes - immunity
Secrete cytokines and chemo lines that maintain populations of leukocytes in skin
76
When challenged by pathogens
Langerhans cells migrate to dermis and lymph nodes and activate a T-cell response Keratinocytes proliferate & secrete cytokines Leucocytes enter skin from blood
77
Merkle cells location
Basal epidermis
78
Merkle cell function
Light touch
79
Where are pacinian corpuscle located
Dermis
80
Where are meissner corpuscles located
Dermal-epidermal junction Dermal papillae
81
Pacinian corpuscle function
Pressure/vibration
82
Meissner corpuscle function
Touch
83
Thermoregulation
Insulation Heat loss
84
Insulation
Subcutaneous fat
85
Temperature range
27 degrees- 37 degrees - 42 degrees
86
Heat loss
Cutaneous blood flow Eccrine sweating Hair
87
Cutaneous blood flow and heat loss
Deep vascular plexus (lower reticular dermis) Superficial vascular plexus (upper reticular dermis) Loops of blood vessels from superficial plexus extend to reticular dermis
88
What is the most common type of sweat glands
Eccrine glands
89
Heat storage equation
metabolism – work – evaporation +/- radiation +/- conduction +/- convection
90
What does evaporation depend on
Surface area exposed to environment Temperature and relative humidity of ambient air Convective air currents
91
Endothermic homeotherms
Generate and modulate our own heat through metabolism
92
What controls blood flow in dermal vascular plexuses
Autonomic regulation
93
Which type of innervation does hairless skin have
Only cholinergic
94
Sympathetic alpha-noradrenergic
Vasoconstriction
95
Sympathetic cholinergic
Vasodilation
96
Types of innervation in hairy skin
Sympathetic alpha-noradrenergic Sympathetic cholinergic
97
What plays a role in active vasodilation
Sympathetic cholinergic nerves Nitric oxide
98
Number of eccrine sweat glands
1.6-4 million
99
Amount of sweat per hour
1-3L
100
What is the limiting factor of sweat production
Availability of water
101
Piloerection (goosebumps)
Arrector pili muscles innervated by sympathetic α1-adrenergic fibres Contraction raises cutaneous hairs Likely little significant impact on heat conservation
102
What are arrector pili muscles innervated by
Sympathetic alpha1-adrenergic fibres
103
Skin as an energy store
Subcutaneous fat acts as an insulator, shock absorber and energy store White adipose connective tissue
104
What is the normal pH of skin?
4.7-5.75
105
What is the normal pH of vagina?
3.3-5
106
In which layer of skin will you find Pacinian corpuscles?
Dermis

SUGER (17 decks)

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