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Dermatology > Skin Structure and Function > Flashcards

Skin Structure and Function Flashcards

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Dermatology Board Prep flashcards
1
Q

What is the dermo-epidermal junction?

A

Interface between epidermis and dermis

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2
Q

What is the key role in epithelial mesenchymal interactions of dermo-epidermal junction?

A

Support, anchorage, adhesion, growth, differentiation of epidermal cells.

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3
Q

What type of membrane is the dermo-epidermal junction?

A

Semi-permeable membrane acting as barrier/filter

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4
Q

What are inherited diseases of the DEJ?

A

Skin fragility conditions due to a mutation in one of the proteins in the DEJ e.g. Epidermolysis bullosa:simplex or dystrophic

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5
Q

What are acquired diseases of the DEJ?

A

Auto-antibodies to proteins in DEJ e.g. pemphigus, pemphigoid, dermatitis herpetiformis

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6
Q

What are the components of the dermis?

A

Cells(mainly fibroblasts, also macs, mast cells, lymphocytes, Langerhans), fibres(collagen, elastin), ground substance (mucopolysaccharides, glycosaminoglycans), blood vessels, lymphatics, nerves

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7
Q

Describe the blood vessels to the skin.

A

Supply greater than metabolic need. Supported walls, horizontal plexus.

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8
Q

Describe the blood flow to the skin.

A

Flow:
Arteriole > precapillary sphincters >
arterial capillaries > venous capillaries >
post-capillary venules > collecting venules

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9
Q

What are examples of localised overgrowths of blood vessels in skin?

A

Capillary or cavernous haemangiomas

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10
Q

What drainage to lymphatic vessels in the skin provide?

A

Continual drainage of plasma proteins, extravasated cells and excess interstitial fluid

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11
Q

What special nerve receptors are there in the skin?

A

Pacinian (pressure) and Meissners (vibration) corpuscles

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12
Q

What are the 3 types of skin glands?

A

Eccrine, sebaceous and apocrine gland

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13
Q

Where are sebaceous glands found?

A

Widely distributed: largest glands present on face and chest

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14
Q

What causes acne?

A

A mixture of increased sebum, blocked ducts and bacterial activity

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15
Q

Where are apocrine glands found?

A

Axillae and perineum

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16
Q

What do aporcrine glands produce?

A

Oily fluid- odour after bacterial composition

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17
Q

Where are eccrine sweat glands found?

A

Whole skin surface- palms, soles and axillae in particular

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18
Q

Describe the nervous supply to eccrine sweat glands

A

Sympathetic cholinergic nerve supply- mental, thermal and gustatory stimulation

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19
Q

What are the functions of eccrine glands?

A

Ultrafiltration, cooling by evaporation, moisten palms/soles to aid grip

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20
Q

What is the epidermis made of?

A

Stratified cellular epithelium

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21
Q

What is the dermis made of?

A

Connective tissue

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22
Q

Where does the epidermis come from>

A

Ectoderm cells form single layer periderm. Gradual increase in cell layers. Periderm cells cast off

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23
Q

Where does the dermis come from?

A

Formed from mesoderm below ectoderm

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24
Q

What are melanocytes?

A

Pigment producing dendritic cells from neural crest

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25
Q

What are the 4 layers of the epidermis?

A

Keratin, granular, prickle cell, basal cell layer

26
Q

What are Blaschko’s lines?

A

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

27
Q

What type of cell make up 95% of the epidermis?

A

Keratinocytes

28
Q

What occurs in differentiation of the epidermis?

A

Keratinocytes migrate from basement membrane. Continuous regeneration of epidermis. 28 days from bottom to top

29
Q

Describe the basal layer

A

Usually 1 cell thick, small cuboidal. Lots of intermediate filaments, highly metabolically active

30
Q

Describe the prickle cell layer

A

Larger polyhedral cells. Lots of desmosomes. Intermediate filaments connect to desmosomes

31
Q

Describe the granular layer

A

2-3 layers flatter cells. Large keratohyalin granules- contain structural filaggrin & involucrin proteins, also Odland (lamellar) bodies. High lipid content. Cornified envelope origin, cell nuclei lost

32
Q

Describe the keratin layer

A

Made of corneocytes (overlapping non-nucleated cell remnants). Insoluble cornified envelope, 80% keratin & filaggrin. Lamellar granules release lipid, tight waterproof barrier

33
Q

Describe oral mucosa

A

Masticatory- keratinized to deal with friction/pressure. Lining- non keratinized. Specialised mucosa- tongue papillae:taste

34
Q

Describe what can be found in ocular mucosa

A

Lacrimal glands, eye lashes, sebaceous glands

35
Q

What cells apart from keratinocytes make up the epidermis?

A

Melanocytes (basal/suprabasal), Langerhans (suprabasal), Merkel (basal)

36
Q

During what time do melanocytes migrate from epidermis to neural crest?

A

First 3 months of foetal development

37
Q

What do melanocytes contain?

A

Organelles: melanosomes

38
Q

What conversion occurs in melanocytes?

A

Tyrosine to melanin pigment: eumelanin (brown/black), Phaeomelanin (red, yellow)

39
Q

What happens when melanosomes become full (melanin granules)?

A

Transferred to adjacent keratinocyte via dendrites

40
Q

What is a malignant melanoma?

A

A tumour of the melanocyte cell line

41
Q

Describe Langerhans cells

A

Mesenchymal origin-bone marrow. Prickle cell level, also found in dermis/lymph nodes. Antigen presenting cells: pick up antigen in skin and circulate to lymph nodes via lymphatic system

42
Q

Describe Merkel cells

A

Basal, between keratinocytes and nerve fibres, mechanoreceptors

43
Q

Describe Merkel cell cancer

A

Rare, caused by viral infection. High mortality

44
Q

Describe hair follicle ‘Pilosebaceous unit’

A

Epidermal plus dermal papilla. Specialised keratins, adjacent sebaceous gland. Pigmentation via melanocytes above papilla

45
Q

Name the 3 phases of hair follicle growth

A

Anagen (growing), Catagen (involuting), Telogen (resting)

46
Q

Name some types of hair follicles

A

Lanugo (in utero), vellus (short hair all over body), terminal (long dark hair produced during puberty)

47
Q

Describe the anagen phase

A

3-7 years, 90% of hairs

48
Q

Describe the catagen phase

A

3-4 weeks, 10% hairs

49
Q

Describe the telogen phase

A

Shedding, each day 50-100

50
Q

Describe nails

A

Specialised keratins, nail matrix/root similar to hair bulb. Growth rate 0.1mm/d, fingers >toes, summer >winter.

51
Q

Describe sebaceous glands pre puberty

A

Quiescent

52
Q

What do sebaceous glands produce?

A

Sebum: squalene, wax esters, triglycerides and free fatty acids

53
Q

What are the functions of sebaceous glands?

A

Control moisture loss, protection from bacterial and fungal infection

54
Q

Are apocrine sweat glands androgen dependent or independent?

A

Dependent

55
Q

What type of gland are your apocrine sweat glands?

A

Scent glands

56
Q

What are the functions of the skin?

A

Barrier, metabolism & detoxification, thermoregulation, immune defence, communication, sensory

57
Q

What is toxic epidermal necrolysis an example of?

A

Acute skin failure

58
Q

What Vit D metabolisation occurs in the skin?

A

Vitamin D: Cholecalciferol > Vitamin D3

59
Q

In what form is Vitamin D3 stored in the liver and kidney?

A

Hydroxycholecalciferol in liver, converted to 1,25-dihydroxycholecaliferol in kidney

60
Q

What thyroid hormone metabolism occurs in the skin?

A

Thyroxine (T4) > Triiodothyronine (T3) (20% in thyroid gland, 80% in peripheral tissues including skin)

Dermatology (14 decks)

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