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Second Year (JBR) > Dermatology Science > Flashcards

Dermatology Science Flashcards

1
Q

What is the embryological origin of the epidermis?

A

Ectoderm

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2
Q

What is the embryological origin of dermis?

A

Mesoderm

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3
Q

In week 14 of development the skin consists of?

A

Basal layer, intermediate layer, periderm (apotheoses 120 days post-fertilisation)

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4
Q

When do melanocytes, sebaceous glands, arrestor pili muscles and hair follicles develop?

A

Week 26

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5
Q

How do melanocytes form?

A

Melanoblast from neural crest migrates to uveal tract and leptomeninges
Settle in skin

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6
Q

What are the 5 layers of the epidermis?

A 
Stratum basale
Straum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
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7
Q

Keratinocytes in the basal layer of epidermis attach to basement membrane via?

A

Hemidesmosomes

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8
Q

The epidermis is normally regenerated every?

A

28 days

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9
Q

How do melanocytes function in the skin?

A

Melanosomes convert tyrosine into melanin pigment with absorbs light
DCs transport melanosomes to adjacent keratinocytes and form protective melanin cap over nucleus to protect basal cell DNA

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10
Q

What colour is eumelanin?

A

Brown/black

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11
Q

What colour is phaeomelanin?

A

Red/yellow

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12
Q

What determines pigment balance in the skin?

A

MC1R gene. Protein converts eumelanin to phaeomelanin

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13
Q

1 defective copy of MC1R results in?

A

Freckling

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14
Q

2 defective copies of MC1R results in?

A

Freckling + Red hair

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15
Q

What are Merkel cells?

A

Pressure receptors

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16
Q

What is contained within basal layer?

A

Keratinocytes
Melanocytes
Merkel cells
Keratin (lots)

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17
Q

In the prickle cell layer keratinocytes are connected by?

A

Desmosomes

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18
Q

Keratinocytes in stratum spinosum produce lamellar bodies. What is their function?

A

Skin barrier

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19
Q

What are Langerhans cells and where are they found?

A

Found in stratum spinosum, dermis and lymph nodes

Mesenchymal immune cells (APCs) - present Ag to T-cells

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20
Q

What makes up the stratum granulosum?

A

2-3 layers of flatter unclear keratinocytes

Large keratohyaline granules with filaggrin + involucrin (proteins)

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21
Q

Which skin layer is the origin of the cornified envelope?

A

Stratum granulosum

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22
Q

What do the keratinocytes in the stratum granulosum produce? Function?

A

Lamellar (aka Odland bodies)

Lipid barrier

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23
Q

What is the stratum lucid?

A

Clear translucent layer found only in palms and soles

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24
Q

The stratum corner serves as a ?

A

Tight waterproof barrier

Insoluble cornified envelope

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25
Q

The stratum corner consists of?

A

Corneocytes (corneodesmosomes)
80% keratin and filaggrin
Lamellar granules (release lipids)

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26
Q

What makes up the epidermal basement membrane?

A

Laminin

Collagen IV

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27
Q

What is the function of the derma-epidermal junction (DEJ)?

A

Messenging - support, anchor, adhesion, growth and differentiation of basal cells

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28
Q

The DEJ is a _______ membrane

A

semi-permeable

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29
Q

What makes up the dermis?

A 
Ground substance (polysaccharide mix), immune cells
Matrix of collagen and elastin
Muscles
Blood vessels
Lymphatics
Nerves
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30
Q

How is blood supplied to dermis?

A

Horizontal plexuses (supply > need)

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31
Q

Outline the nerve supply to skin (dermis)?

A

Somatosensory dermatomes - pacinian (pressure) and meissner (vibration) receptors
ANS - bood vessels, nerves, glands

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32
Q

What is the papillary dermis?

A

Thin dermis found just beneath epidermis

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33
Q

What does the reticular dermis contain?

A

Hair follicles
Nails
Skin glands

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34
Q

What do hair follicles consist of?

A

Pilosebaceous unit

Invaginated epidermal tissue; each associated with dermal sebaceous gland

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35
Q

What makes hair stand up?

A

Arrector pili muscle

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36
Q

How does the arrector pili muscle attach?

A

Proximal - hair bulb

Distal - epidermis

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37
Q

How are hair follicles pigmented?

A

Via above melanocytes

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38
Q

Growth of hair is under _____ influence

A

hormonal (thyroxine, androgens)

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39
Q

90% of hair is in the growing phase known as?

A

Anagen

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40
Q

10% of hair is involuted. Known as?

A

Catagen

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41
Q

How is hair involuted?

A

Dermal papilla sinks and shrink - hair is pushed back to surface

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42
Q

<1% of hair (50-100/day) is in the asynchronous shedding phase known as?

43
Q

What is hair in utero called?

44
Q

What is hair in childhood called?

45
Q

What is adult hair called?

46
Q

What makes up a nail?

A

Specialised keratins in matrix subdivisions (dorsal, intermediated, and ventral plate)

47
Q

How much does a nail grow in a day?

A

0.1 mm
Fingers > toes
Summer > winter

48
Q

Crumbling in parts of an otherwise normal nail indicates?

A

Damage to matrix subdivision preventing proper differentiation

49
Q

What are sebaceous glands?

A

Produce sebum (small oily layer) to cionrol moisture and protect from fungus/bacteria

50
Q

Where are sebaceous glands found most and what influences their secretion?

A

Most on face/chest

Sensitive to hormones - inactive before puberty

51
Q

What are apocrine glands?

A

Secrete oily fluid - odour and are part of pilosebaceous unit
Unknown function
Found mostly in axillae and perineum

52
Q

What are eccrine glands?

A

Sweat glands - control moistening and grip on soles. NaCl and HCO3 are reabsorbed

53
Q

Where are eccrine glands found?

A

Whole skin (2-4 million) - can produce >10L a day

54
Q

Under what control are sweat glands?

A

Sympathetic cholinergic nerve supply

Stimulated by mental/thermal/gustatory

55
Q

What are the three layers of skin?

A

Epidermis
Dermis
Sub-cutis (fat)

56
Q

What is hyperkeratosis?

A

Thickened surface keratin layer

57
Q

What is parakeratosis?

A

High epidermal turnover - immature keratin, nuclei persist

58
Q

What is acanthuses?

A

Increased epithelial thickness

59
Q

What is papillomatosis?

A

Irregular epithelial thickening (bumpy)

60
Q

What is spongiosis?

A

Oedema filled vesicles

61
Q

What are the functions of skin?

A 
Barrier
Metabolism and detox
Thermoregulation
Immune defence
Communication (appearance, odour) 
Sensory
62
Q

Outline vitamin D metabolism in the skin?

A

Cholecalciferol is concerted to Vitamin D3 (290-320 mm UV light)
Stored in liver with dietary vitamin D
Converted to calcitriol in kidney

63
Q

What percentage of T4 to T3 conversion occurs in the skin?

64
Q

how do keratinocytes in the epidermis contribute to immune defence?

A

Cell surface receptors sense pathogens and produce AMPs, cytokines and chemokine in response

65
Q

The skin contains mesenchymal T-cells including CD4+, CD8+, NK cells and other subsets. How to TH1 cells activate macrophages?

A

via IL-2 and IFN-y

66
Q

The skin contains mesenchymal T-cells including CD4+, CD8+, NK cells and other subsets. How do TH2 cells help B cells make antibodies?

A

Via IL-4, 5 and 6

67
Q

Plasmocytoid dendritic cells produce which marker of diseased skin?

68
Q

What occurs in the sensitisation phase of type IV hypersensitivity?

A

Haptens presented to CTLs and down-regulatory DC4+ T cells in lymph nodes

69
Q

What occurs in the efferent phase of type IV hypersensitivity?

A

Same happens as in sensitisation phase activate CTLs causing cytokines and chemokine to recruit leukocytes

70
Q

Group A strep causes which kinds of infections?

A

Throat, severe skin infections

71
Q

How are GAS organisms classified?

A

Lancefield (M - emm protein) antigen

72
Q

What are the major serotypes of GAS?

73
Q

Which serotypes of GAS cause severe invasive disease?

74
Q

Which GAS serotype causes epidemics?

75
Q

Which virulence factos do GAS possess?

A

Superantigen toxins

Haemolysins - tissue damage and ulcer

76
Q

Which adhesions and evasins do GAS possess?

A

Adhesins for oro-/naso-pharynx

Hyaluronic acid capsule to evade phagocytosis

77
Q

Which organisms causes neonatal meningitis?

A

Group B Strep

78
Q

Which classification do Enterococcus fall under?

A

y-haemolytic Strep

79
Q

E. faecalis and E. faecium are bowel ______ that may cause?

A

commensals

UTIs

80
Q

Staph aureus causes which kinds of infectioN?

A

Skin, wound, bone, joint

81
Q

Which toxins may S. aureus possess?

A

Enterotoxin
SSSST
PVL
SUperantigen TSST-1

82
Q

Most strains of CA-MRSA contain which S. aureus released toxin?

83
Q

How do super antigens activate more T-cells?

A

Non-Specific activation - don’t require specific antigen

84
Q

What is the standard treatment for Staph aureus unless it’s MRSA?

A

Flucloxacillin

85
Q

S. saprophytic causes?

A

UTIs in women of child-bearing age

86
Q

Which competitive bacterial flora are found in the skin?

A

S. epidermidis
Corneybacterium
Proprionobacterium (acne)

87
Q

What is a gel?

A

semisolid with HMW polymers

88
Q

What is a cream?

A

Semisolid emulsion of oil in water with emulsifier and preservative

89
Q

What is an ointment?

A

Semisolid grease without preservatives

90
Q

What is a paste?

A

Semisolid with fine powdered material

91
Q

What is lotion?

A

Solution of meds in water

92
Q

How do you calculate the rate of absorption (J) of topical drugs?

A

Kp (permeability coefficient) x Cv (concentration of drug in vehicle)

93
Q

How potent is hydrocortisone 1%?

94
Q

How potent is mometasone/betamethasone/valerate 0.1%?

95
Q

How potent is clobetasol/proprionate 0.05%

A

Very potent

96
Q

How potent are modrasone, clobetasone and butyrate 0.05%

97
Q

Which anti-septic can be used as a rinse-bath for acute exudative eczema, popholyx?

A

Potassium permangenate

98
Q

How can topic drugs be systemically absorbed?

A

Transdermal - LMW

Enhanced by iontophoresis/electroporation

99
Q

What is the advantage of TDD (transdermal drug delivery)?

A

Avoids first pass metabolism

100
Q

Subcutaneous admin is just for ___ molecular weight drugs

101
Q

What are the advantages of subcutaneous administratioN?

A

Avoids first-pass metabolism

Can introduce depot

102
Q

How do different skin surfaces rank in permeability

A

nail &laquo_space;palm/sole < trunk/extremities < face/scalp < scrotum

103
Q

What is the DLQI?

A

Dermatology life quality index

Second Year (JBR) (10 decks)

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