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Y2 - Dermatology > Skin Structure and Function > Flashcards

Skin Structure and Function Flashcards

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Dermatology Board Prep flashcards
1
Q

What makes up the skin?

A 
Epidermis
Dermo-epidermal junction
Dermis
Sub-cutis
Appendages
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2
Q

What are examples of appendages?

A

Nails
Hair
Glands

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3
Q

How is the epidermis formed in an embryo?

A

From the ectoderm
Ectoderm cells forma single layer called periderm
Gradual increase in layers of cells
Periderm cells cast off

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4
Q

How is the dermis formed in an embryo?

A

From mesoderm below ectoderm

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5
Q

How are melanocytes formed in an embryo?

A

From the neural crest

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6
Q

What are melanocytes?

A

Melanin pigment producing dendritic cells

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7
Q

At what stage of development is the skin at in week 4, 16 and 26 of development?

A

4 - Periderm above the basal layer and dermis
16 - Epidermis fully formed but without appendages
26 - skin fully formed, including appendages and melanocytes

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8
Q

What are Blashco’s lines?

A

Lines that show the developmental growth pattern of skin

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9
Q

What type of cell is the epidermis made up of?

A

Stratified squamous

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10
Q

What are the layers of the epidermis?

A

Keratin layer
Granular layer
Prickle cell layer
Basal layer

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11
Q

What is the keratin layer made of (and what are these cells)?

A

Corneocytes

Overlapping non-nucleated cell remnants

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12
Q

What proteins are corneocytes mostly made up of?

A

Keratin and filaggrin

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13
Q

How does the keratin layer form a waterproof barrier?

A

Contains lipids released by lamellar granules
Filaggrin fragments hold onto water, lipids repel them
Amino acids bind water on the inside

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14
Q

What is the granular layer of the epidermis?

A

2-3 layers of flatter cells

Nuclei are lost so they are no longer proper cells

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15
Q

What is the prickle cell layer?

A

Layer of larger polyhedral cells

Cells are migrating upwards from the basal layer to the granular layer

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16
Q

Why are desmosomes present in the prickle cell layer?

A

Allow both adhesion (for stability) and flexibility (so cells can move upwards)

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17
Q

What is the basal layer?

A

Usually one cell thick layer of small cuboidal cells

Highly metabolically active

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18
Q

How do cells move to the surface of skin?

A

Basal layer contains stem cells
Daughter cells are produced, one stays in the basal layer and one moves up to prickle cell layer
From there they differentiate into the granular layer
Top layer of cells are dead - sloughed off and held together with a layer that stops water loss

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19
Q

Roughly how long does it take a cell to move from the basal layer to the surface of skin?

A

28 days

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20
Q

What factors control epidermal turnover?

A

Growth factors
Cell death
Hormones

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21
Q

When is there loss of control of epidermal turnover?

A

Skin cancer

Psoriasis

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22
Q

What is the difference between psoriatic skin and normal skin?

A

Thick keratin layer

Irregular dermo-epidermal junction

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23
Q

What other cells are in the epidermis?

A

Melanocytes
Langerhans cells
Merkel cells

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24
Q

What causes warts?

A

HPV infection of keratinocytes

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25
Q

Where are mucosal membranes present?

A

Eyes, mouth, nose, genito-urinary and GI tracts

Basically anywhere that produces mucus

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26
Q

What is different about oral mucosa?

A

Masticatory mucosa is keratinised to deal with friction
Lining mucosa is non-keratinised
Has specialised mucosa in the tongue papillae for taste

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27
Q

Where are the non-keratinocyte cells located in the epidermis?

A

Melanocytes - basal and suprabasal
Langerhans - suprabasal
Merkel cells - basal

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28
Q

From what do melanocytes produce melanin pigment?

A

Tyrosine

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29
Q

What organelle do melanocytes contain?

A

Melanosomes

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30
Q

What is the function of melanosomes?

A

Melanosomes extend to the tip of the desmosome to be taken up by neighbouring melanocytes

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31
Q

What is the function of melanin?

A

Forms a thick brownish cap that doesn’t let light penetrate to protect the nuclear DNA in basal cells from radiation

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32
Q

What conditions affect melanocytes?

A

Vitiligo
Albanism
Malignant melanoma

33
Q

Where are langerhans cells formed?

A

Bone marrow

34
Q

Where are langerhans cells found?

A

Prickle cell layer
Dermis
Lymph nodes

35
Q

What is the function of langerhans cells?

A

Immune cells
Antigen presenting
Circulate to lymph nodes via lymphatics

36
Q

What is the function of merkel cells?

A

Mechanoreceptors - detect touch and transmit a signal to the rain to perceive it

37
Q

What causes merkel cell cancer?

A

Viral infection

38
Q

What is a pilosebaceous unit?

A

Hair follicle plus its adjacent sebaceous glands

39
Q

What do sebaceous glands produce?

A

Sebum

40
Q

What are the phases of hair follicle growth?

A

Anagen - growing
Catagen - involuting
Telogen - resting

41
Q

What are conditions affecting hair?

A

Virilisation (too much hair)

Alopecia areatica

42
Q

What are the parts of a nail?

A 
Nail matrix
Lunula
Nail plate
Nail bed (below plate)
Hyponychium
43
Q

What is the function of the demo-epidermal junction?

A

Support, anchorage, adhesion and differentiation of basal cells
Semi-permeable membrane acts as barrier and filter

44
Q

What are conditions of the demo-epidermal junction?

A

Bullous pemphigoid

Epidermolysis bullosa

45
Q

How is bullous pemphigoid diagnosed?

A

Immunofluorescence

46
Q

Which layer of the skin contains connective tissue?

A

Dermis

47
Q

What are the functions of the dermis?

A

Gives strength

Contains muscles, blood vessels, lymphatics and nerves

48
Q

What cells make up the dermis?

A 
Fibroblasts (mainly)
Macrophages
Mast cells
Lymphocytes
Langerhans cells
49
Q

What fibres make up the dermis?

A

Collagen (90%)

Elastin

50
Q

What are collagen and elastin made by?

A

Fibroblasts

51
Q

What causes photoaging?

A

Years of UV exposure causes collagen to be lost - skin collapses
Loss of elastic fibres leads to wrinkles

52
Q

What is an examples of a skin condition affecting blood vessels?

A

Angioma

53
Q

What is an examples of a skin condition affecting lymphatics?

A

Chronic lymphoedema

54
Q

What is the function of Pacinian corpuscles?

A

Sense pressure

55
Q

What is the function of Meissner’s corpuscles?

A

Sense vibration

56
Q

What do pacinian corpuscles look like histologically?

A

Onion rings

57
Q

What is an example of a condition affecting nerves?

A

Neurofibromatosis

58
Q

What are the different types of skin gland?

A

Sebaceous glands
Apocrine glands
Eccrine glands

59
Q

What is the function of sebaceous glands?

A

Lubricate hair follicles
Produce sebum
Control moisture loss
Protection from fungal infection

60
Q

Which glands are hormone sensitive and dormant before puberty?

A

Sebaceous

Apocrine

61
Q

What causes acne?

A

Sebaceous glands are too large and active, blocking follicles and causing acne

62
Q

Where are sebaceous glands located?

A

Widely distributed, everywhere with hair

largest are in face and chest

63
Q

Where are apocrine glands located?

A

In the axillae and perineum (underarms and groin)

64
Q

Which hormone are apocrine glands dependant on?

A

Androgen

65
Q

What is the function of apocrine glands?

A

Part of pilosebaceous gland, produce oily fluid which causes odour after bacterial decomposition

66
Q

Where are eccrine glands located?

A

Whole skin surface but particularly palms, soles and axillae

67
Q

What kind of stimulation activates eccrine sweat glands?

A

Mental, thermal and gustatory stimulation - e.g. sweaty when nervous, hot or eating spicy food

68
Q

What are the functions of eccrine glands?

A

Ultrafiltration of fluids
Cooling by evaporation
Moisten palms/soles to aid grip

69
Q

What is acute skin failure, and what often causes it?

A

Lifting up of the epidermis at the demo-epidermal junction due to toxic epidermal necrolysis
Caused by medication - side effect

70
Q

What are the functions of the skin?

A 
Barrier
Metabolism and detoxification
Thermoregulation
Immune defence
Communication
Sensory functions
71
Q

What metabolism does the skin do?

A

Vitamin D metabolism

Thyroid hormone metabolism

72
Q

What vascular changes happen when the skin is too hot or cold?

A

Too hot - vasodilation

Too cold - vasoconstriction

73
Q

What happens if the skin’s barrier function fails?

A

Fluid loss and dehydration
Protein loss leading to hypoalbuminaemia
Infection

74
Q

What happens if the skin’s thermoregulatory function fails?

A

Heat loss leading to hypothermia

75
Q

What happens if the skin’s immune defence fails?

A

Spread of infection

76
Q

What happens if the skin’s metabolic function fails?

A

Disordered thyroxine metabolism

77
Q

What happens if the skin’s communication function fails?

A

Inability to display healthy skin - stigma

78
Q

What happens if the skin’s sensory function fails?

A

Pain sensation

Y2 - Dermatology (12 decks)

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