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Dermatology > Structure and function of the skin > Flashcards

Structure and function of the skin Flashcards

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Dermatology Board Prep flashcards
1
Q

What is the epidermis made of?

A

Stratified squamous epithelium

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2
Q

What is the dermis made of?

A

Connective tissue

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3
Q

Where is the epidermis derived from embryologically?

A

Ectoderm

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4
Q

Where is the dermis derived from embryologically?

A

Mesoderm

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5
Q

Where do melanocytes migrate from embryologically?

A

Neural crest

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6
Q

What are Blaschko’s lines?

A

Developmental growth pattern of skin – not following vessels, nerves or lymphatics

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7
Q

What is 95% of the epidermis made of?

A

Keratinocytes

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8
Q

What are the 4 layers of the epidermis?

A

Basal layer, prickle cell layer, granular layer, keratin layer

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9
Q

How long does it take keratinocytes to travel from the basement membrane to the top layer of skin?

A

28 days

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10
Q

How thick is the basal layer? What cell type is it?

A

1-3 cells thick, small cuboidal

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11
Q

Describe the prickle cell (spinous) layer

A

Larger than basal cells, polyhedral cells, composed of keratinocytes, lots of desmosomes, intermediate filaments connect to desmosomes

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12
Q

Describe the granular layer

A

Composed of flattened cells containing the darkly staining keratohyalin granules, Odland bodies, high lipid content, cell nuclei lost

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13
Q

Describe the keratin layer (horny layer/ stratum corneum)

A

Corneocytes (flattened dead enucleate keratinocytes), tight waterproof barrier, lamellar granules release lipid

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14
Q

What is Nelson’s syndrome?

A

Excess α-MSH production in the pituitary, person appears darker than they should

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15
Q

Where do Langerhans cells orginate from?

A

Mesenchyme, bone marrow

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16
Q

Where are Langerhans cells found?

A

Prickle cell layer of epidermis, dermis, lymph nodes

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17
Q

What type of cell is the Langerhan cell? What MHC type do they have?

A 
Antigen presenting cell (presents to T cells), dendritic cell (like the melanocyte)
MHC class II antigens
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18
Q

What are Merkel cells and where are they found?

A

Non-dendritic cells, lying in or near the basal layer and are the same size as keratinocytes
Mechanoreceptors
Found in normal epidermis between keratinocytes & nerve fibres
Sparse desmosomes connect these cells to neighbouring keratinocytes
Concentrated in localised thickenings of the epidermis near hair follicles

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19
Q

What is merkel cell cancer caused by? What is the mortality rate like?

A

Viral infection, rare

High mortality

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20
Q

What is a pilosebaceous unit?

A

A hair follicle and its associated sebaceous glands

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21
Q

What causes hair pigment?

A

Melanocytes in the hair bulb

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22
Q

Which muscles are responsible for the erection of hairs that causes goosebumps?

A

Arrector pili muscles

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23
Q

Which 3 layers of skin are present at 4 weeks foetal development?

A

Periderm
Basal layer
Dermis (corium)

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24
Q

At which stage of foetal development do we see the 4 layers of epidermis + dermis?

A

16 weeks

25
Q

What are arrector pili muscles supplied by?

A

Adrenergic nerves

26
Q

What are the 3 phases of hair growth? How long does each stage last on the scalp?

A

Anagen (growing) - 3-7 yrs
Catagen (involuting) - 3-4 weeks
Telogen (resting) - 3 months, each day 50-100 hairs

27
Q

When are lanugo hairs shed?

A

About 1 month before birth

28
Q

Which hairs replace lanugo hairs?

A

Vellus hairs

29
Q

Define hirsutism

A

Male pattern hair growth in a woman

30
Q

Define virilisation

A

Development of male physical characteristics (e.g. muscle bulk, body hair, deep voice) in a female or precociously in a boy
Typicall due to excess androgen production

31
Q

Which type of hair loss is associated with autoimmune diseases?

A

Alopecia areata

32
Q

Nail growth rate

A

0.1 mm per day

From matrix to free edge is ~6 months

33
Q

What effect might psoriasis have on nail growth rate?

A

Increases it

34
Q

Another name for dermo-epidermal junction

A

Basement membrane

35
Q

2 layers of the dermo-epidermal junction

A

Lamina lucida & lamina densa

36
Q

How is the DEJ connected to the dermis and epidermis?

A

To the epidermis by hemidesmosomes from basal cells to lamina lucida
Anchoring filaments connect hemidesmosomes to lamina densa
To the dermis by anchoring fibrils from lamina densa to dermis

37
Q

Autoantibodies to proteins in DEJ can cause which diseases of the DEJ?

A

Pemphigus, pemphigoid, dermatitis herpetiformis

38
Q

Inherited diseases of the DEJ

A

Epidermolysis bullosa simplex (EBS)

Dystrophic epidermolysis bullosa (EBD)

39
Q

Positive immunofluorescence suggest which DEJ disease?

A

Bullous pemphigoid

40
Q

Components of the dermis

A

Cells - mainly fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells

Fibres – collagen, elastin

Ground substance

Blood vessels, lymphatics, nerves

41
Q

Why is collagen important?

A

Tensile strength

42
Q

Purpose of fibroblasts

A

Synthesise connective tissue matrix of dermis

Secrete collagen

43
Q

Functions of ground substance

A

It binds water, allowing nutrients, hormones and waste products to pass through the dermis
It acts as a lubricant between the collagen and elastic fibre networks during skin movement
Allows the dermis to act as a shock absorber

44
Q

Purpose of blood vessels in skin

A

Regulate body temperature

45
Q

Deep plexus arterioles supply…

A

Sweat glands & hair papillae

46
Q

Define angioma & haemangioma

A 
Angioma = an abnormal growth produced by the dilatation or new formation of blood vessels
Haemangioma = a benign tumour of blood vessels, often forming a red birthmark
47
Q

What do Pacinian & Meissner’s corpuscles sense?

A

Pacinian - pressure

Meissner’s - vibration

48
Q

Where are apocrine sweat glands found?

A

Axilla & perineum

49
Q

Which of the 3 glands found in skin does not open into a hair follicle?

A

Eccrine

50
Q

Where are eccrine glands found?

A

Whole skin surface (inc. palms, soles)

Especially axillae

51
Q

Purpose of eccrine sweat glands?

A

Regulating body temperature

Moisten palms / soles to aid grip

52
Q

What do eccrine glands secrete?

A

Water, electrolytes, lactate, urea, ammonia

53
Q

Antimicrobial peptides found on the skin

A

Defensins and cathelcidins

54
Q

Wavelength of light used to make vitamin D

A

290 to 320 nm UV

55
Q

Layer of the skin that scabies affects

A

Keratin layer

56
Q

Who does crusted scabies affect?

A

Immunosuppressed

57
Q

Cause of eczema herpeticum

A

HSV

58
Q

Difference between discoid lupus and systemic lupus

A

Discoid affects just the skin & doesn’t go internal

Systemic affects systems of the body

Dermatology (10 decks)

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