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dermatology > Structure and function of skin 1-4 > Flashcards

Structure and function of skin 1-4 Flashcards

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Dermatology Board Prep flashcards
1
Q

What germ layers are the epidermis and dermis formed from?

A

Epi- ecto

Dermis- meso

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2
Q

What are the four layers of the epidermis?

A

Keratin layer
Granular cells
Prickle cells
Basal cells

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3
Q

Where do melanocytes develop from?

A

Neural crest

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4
Q

What does disease which abides Blatschko’s iines indicate?

A

That it is congenital

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5
Q

What are the possible consequences if control is lost over skin turnover?

A

Skin cancer

Psoriasis

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6
Q

What is the rate of migration of keratinocytes in psoriasis compared to normally?

A

around 3-5 days compared to 28 days normally

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7
Q

What is the basal cell layer characterised by?

A

Single layer of cells, many intermediate filaments

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8
Q

What is the distinguishing feature of the prickle cell layer?

A

Desmosomes between cells- cells are motile but retain a cohesive structure

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9
Q

Which layer of the epidermis is the origin of the cornified envelope?

A

Granular layer

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10
Q

Which proteins are contained within keratohyalin granules in the granular layer, and what is their purpose?

A

Fillagrin and involucrin

Structural

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11
Q

What are corneocytes and where are they found?

A

Non-nucleated remnants of keratinocytes, within the keratin layer

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12
Q

Truncation mutations in fillagrin and involucrin are associated with which disease?

A

Eczema

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13
Q

What is the distinguishing feature of the keratin layer?

A

Waterproof, but can also transpire- helps maintain fluid homeostasis

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14
Q

Which layer of the epidermis is infected by HPV, and how does it cause the characteristic symptoms?

A

Prickle cell layer- reactive hyperkeratinisation

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15
Q

Which reaction takes place in melanosomes?

A

Tyrosine is converted to melanin

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16
Q

How does the melanin produced in melanocytes protect adjacent cells from UV damage?

A

“full” melanosomes are transferred to adjacent keratinocytes via dendrites, where they form a protective shield around the nucleus and absorb UV light

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17
Q

Describe the underlying cause in these diseases associated with melanin production:

a) Vitiligo
b) albinism
c) Nelson’s syndrome

A

a) autoimmune destruction of melanocytes
b) disruption in biochemical pathway of melanin production
c) excess melanin stimulating hormone from the pituitary

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18
Q

What is the function of Langerhans cells?

A

Antigen presenting cells of the skin

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19
Q

Which structural element are Langerhans cells distinguished by?

A

Racket organelles (Birbeck granules)

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20
Q

Where are Merkel cells found and what is their function?

A

In the basal layer between keratinocytes and nerve fibres- mechanoreceptors for the sensation of light touch

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21
Q

Where does hair pigmentation derive from?

A

Melanocytes above the dermal papilla

22
Q

What is the hair shaft lubricated by?

A

Adjacent sebaceous glands

23
Q

What are the three phases of hair growth?

A

Anagen -growing (90% of hairs)
Catagan- involuting (10%)
Telogen- shedding

24
Q

What is telogen effluvium and when does it typically occur?

A

Thinning/shedding of hair

Post-partum and in ageing males (male-pattern baldness)

25
Q

What is alopecia areata?

A

Autoimmune hair loss

26
Q

Where does nail growth occur from?

A

The nail matrix

27
Q

What are the three layers of the basement membrane?

A

Lamina lucida
Lamina densa
Sub-lamina dense

28
Q

How are the basal cells of the epidermis linked to basement membrane?

A

Hemidesmosomes

29
Q

How are the cells of the papillary dermis linked to the basement membrane?

A

Anchoring fibrils

30
Q

What causes

a) epidermolysis bullosa
b) bullous pemphigoid

A

a) lack of adhesion at the DEJ causing blistering

b) auto-antibodies to DEJ proteins

31
Q

What are the main fibres found in the dermis, and which cells produce them?

A

Collagen and elastin, secreted by fibroblasts

32
Q

What kinds of cells are found in the dermis?

A 
Fibroblasts
Macrophages
Langerhans cells
Lymphocytes
Mast cells
33
Q

What is ground substance?

A

Polysaccharides and glycosaminoglycans- an intercellular amorphous gelatinous material that resists compression

34
Q

What is photoaging?

A

Characteristic changes to skin caused by chronic UV exposure

35
Q

What is solar elastosis?

A

Accumulation of abnormal elastin in the skin of patients with history of chronic UV overexposure

36
Q

Describe the blood supply to the dermis.

A

Greater than the metabolic needs of the tissue

Superficial (supplies the dermis) and deep vascular plexuses

37
Q

What is an angioma?

A

Localised overgrowth of blood vessels in fixed dilatation. Often seen from birth

38
Q

Describe the lymphatic drainage of the dermis.

A

Sub-epidermal networks of small vessels leading to larger contractile lymphatic trunks.
Jobs- drainage of plasma proteins, extravasated cells, excess tissue fluid

39
Q

What can be the consequence of blockage in the lymphatic vessels of the skin?

A

Chronic lymphoedema

40
Q

Which sensory corpuscles are responsible for the sensation of

a) pressure
b) vibration

A

a) Pacinian

b) ) Meissners

41
Q

Other than sensory, describe the nerve supply to the skin

A

Autonomic- parasympathetic and sympathetic motor fibres

42
Q

What causes neurofibromatosis?

A

Overgrowth of neural tissue in the skin

43
Q

Which substance is produced by sebaceous glands?

A

Sebum- antibacterial

44
Q

What causes acne? Why is it more prominent in puberty?

A

Overproduction of sebum, blockage of sebaceous glands, bacterial activity
Sebaceous glands are hormone sensitive

45
Q

What is the role of apocrine glands and where are the found?

A

Produce sweat- in the axilla and perineum

46
Q

Where are eccrine sweat glands found and what is their purpose?

A

The whole skin- ultrafiltration and cooling by evaporation

47
Q

What is the innervation of the eccrine sweat glands?

A

Sympathetic supply- inputs from mental, thermal and gustatory systems

48
Q

How is the skin involved in:

a) Vitamin D metabolism
b) Thyroid hormone metabolism
c) Drug metabolism

A

a) 290-320nm UV light converts cholecalciferol to Vit D3
b) conversion of T4-T3
c) Cytochrome enzymes are present in skin

49
Q

What actions are initated by skin thermoreceptors to regulate temperature?

A

Sweating
Shivering
Hair erection
Changes in blood flow

50
Q

For each function of the skin, describe what the consequences of skin failure might be:

a) barrier
b) metabolism
c) thermoregulation
d) communication/social
e) immune defebce

A 
a) Fluid loss and dehydration
Protein loss
Infection
b) disordered thyroxine metabolism
c) hypothermia
d) stigma/social isolation
e) spread of infection

dermatology (22 decks)

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