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(BMED) TOB 1-5 > 4.2 - Skin > Flashcards

4.2 - Skin Flashcards

1
Q

List 3 functions of melanocytes.

A
  1. Pigmentation
  2. Protection from UV radiation
  3. Antigen-presenting (dendritic)
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2
Q

Why do Caucasians have lighter skin?

A

Melanocytes produce less melanin

Note: Caucasians and POC have the same NUMBER of melanocytes

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3
Q

List 4 conditions fair-skinned people are more susceptible to.

A
  1. Sunburn
  2. Freckling
  3. Aging
  4. Skin cancer
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4
Q

What is the most common skin cancer?

A

Basal cell carcinoma

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5
Q

What causes basal cell carcinoma?

A

Neoplasm of basal cells

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6
Q

What causes malignant melanoma?

A

Neoplasm of melanocytes

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7
Q

What causes moles?

A

Benign growths of melanocytes

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8
Q

What causes vitiligo?

A

Auto-immune destruction of melanocytes

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9
Q

Why might vitiligo have a symmetrical nature?

A

Melanocytes all derive from the neural crest

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10
Q

What causes alopecia?

A

Auto-immune destruction of hair follicles

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11
Q

What causes male-pattern hair loss?

A

Auto-immune destruction of hair follicles in response to testosterone

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12
Q

Compare alopecia areata, alopecia totalis, and alopecia universalis

A

Areata: spots of hair loss
Totalis: total scalp hair loss
Universalis: loss of all body hair

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13
Q

What causes scarring alopecia?

A

Damage to stem cells in hair follicles as a result of scarring

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14
Q

Describe the appearance of actinic keratosis.

A

Rough, scaly patches of skin; pre-cancerous

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15
Q

What causes actinic keratosis?

A

Dysplasia of keratinocytes due to sun exposure

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16
Q

What causes psoriasis?

A

Extreme proliferation of the basal layer reduces cell turnover to 3-7 days, manifesting as scaling

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17
Q

What causes freckles?

A

UV-induced hyper-production of melanin

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18
Q

What causes actinic lentigo (a.k.a. age spots or liver spots)?

A

UV-induced hyperplasia of melanocytes

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19
Q

Why do freckles fade while liver spots do not?

A

Freckles: same number of melanocytes transiently produce more melanin
Liver spots: number of melanocytes increases

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20
Q

What causes sunburn?

A

Keratinocyte apoptosis due to sun exposure

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21
Q

List 2 symptoms of sunburn.

A
  1. Reddening

2. Swelling

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22
Q

List 4 skin conditions associated with long-term sun exposure.

A
  1. Actinic keratosis
  2. Squamous cell carcinoma
  3. Basal cell carcinoma
  4. Malignant melanoma
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23
Q

What are 2 treatments for psoriasis?

A
  1. Vitamin D analogues (promote differentiation)

2. Steroids (suppress inflammation)

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24
Q

List 4 functions of skin.

A
  1. Barrier
  2. Sensation
  3. Thermoregulation
  4. Psychosexual communication
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25
Q

What are the skin’s 2 means of thermoregulation?

A
  1. Vascular (i.e., dilation and constriction of blood vessels)
  2. Sweating (i.e., evaporation of sweat causes cooling)
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26
Q

What component of the skin allows it to perform its sensory function?

A

Sensory nerves

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27
Q

What layer of the skin provides a barrier against exogenous materials?

A

Stratum corneum

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28
Q

What are the 4 main layers of the epidermis?

A
  1. Stratum CORNEUM
  2. Stratum GRANULOSUM
  3. Stratum SPINOSUM
  4. Stratum BASALE
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29
Q

Which epidermal layer is only present in the palms and soles?

A

Stratum LUCIDUM

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30
Q

What shape are the cells of the stratum basale?

A

Columnar or cuboidal

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31
Q

What shape are the cells of the stratum spinosum?

A

Irregular polyhedral

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32
Q

What holds the cells of the stratum spinosum together?

A

Desmosomes

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33
Q

What shape and colour are cells of the stratum granulosum?

A

Squamous

Dark (due to granules of keratohyalin)

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34
Q

What shape and colour are the cells of the stratum lucidum?

A

Squamous

Translucent

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35
Q

What is the predominant cell type in the epidermis?

A

Keratinocytes

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36
Q

What do keratinocytes produce?

A

Keratins

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37
Q

What is the function of keratins?

A

Strength

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38
Q

Where do keratinocytes divide?

A

Stratum basale

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39
Q

Where do keratinocytes lose their ability to divide and begin to differentiate?

A

Stratum spinosum

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40
Q

Where do keratinocytes lose their plasma membranes and begin to differentiate into corneocytes?

A

Stratum granulosum

41
Q

Where would you find keratohyallin granules?

A

Stratum granulosum

42
Q

List 5 components of keratohyallin granules.

A
  1. Keratins (intermediate filaments)
  2. Phospholipases (degrade plasma membrane)
  3. Fillaggrin (binds keratins)
  4. Involucrin (forms cornified envelope)
  5. Transglutaminases (cross-link proteins)
43
Q

What is the role of filaggrin?

A

Binds keratins in the skin

Remember: filament aggregating

44
Q

What layer contains flattened corneocytes?

A

Stratum corneum

45
Q

How long does it take for a keratinocyte to travel from the basal layer to the stratum corneum?

A

28 days

46
Q

What happens to keratinocytes in the stratum basale?

A

Divide

47
Q

What happens to keratinocytes in the stratum spinosum?

A

Stop dividing

Begin to differentiate

48
Q

What happens to keratinocytes in the stratum granulosum?

A

Lose their cell membranes

Begin to differentiate into corneocytes

49
Q

What is the main cell type found in the stratum corneum?

A

Flattened corneocytes

50
Q

How do corneocytes break down?

A

Desmosomes weaken

Corneocytes sloughed off as squames (a.k.a. scales)

51
Q

What thickens the cornified layer of skin?

A

Exposure to abrasion

52
Q

Describe the process of keratinocyte differentiation.

A

Stratum basale: cells divide
Stratum spinosum: cells stop dividing and begin to differentiate
Stratum granulosum: cells lose their plasma membranes and begin to differentiate into corneocytes
Stratum corneum: flattened corneocytes form a barrier

53
Q

What is the function of dendritic cells?

A

Antigen-presenting

54
Q

What are melanocytes?

A

Dendritic cells of neural crest origin found in the stratum basale

55
Q

What is the origin of melanocytes?

A

Neural crest

56
Q

Where are melanocytes found?

A

Stratum basale

57
Q

What is melanin?

A

Pigment produced by melanocytes

58
Q

What are Langerhans cells?

A

Dendritic cells of bone marrow origin found in the stratum spinosum

59
Q

What is the origin of Langerhans cells?

A

Bone marrow

60
Q

Where are Langerhans cells found?

A

Stratum spinosum

61
Q

Compare melanocytes and Langerhans cells.

A

Melanocytes: dendritic, neural crest origin, found in the stratum basale
Langerhans cells: dendritic, bone marrow origin, found in the stratum spinosum

62
Q

What are Merkel cells?

A

Mechanoreceptors receptors located in the stratum basale

63
Q

In which part of the body are Merkel cells (mechanoreceptors) particularly abundant?

A

Fingertips

64
Q

How would you determine the prognosis in malignant melanoma?

A

Depth of malignant cell penetration

Note: neoplasm above the basement membrane is associated with good prognosis

65
Q

What is the prognosis for a malignant melanoma with a Breslow thickness of < 1 mm?

A

5-year survival rate of 95-100%

66
Q

What is the prognosis for malignant melanoma with a Breslow thickness of > 4 mm?

A

5 year survival rate of < 50%

67
Q

What are the ABCD’s of melanoma and what are they used for?

A
  1. Asymmetry
  2. Border
  3. Colour
  4. Diameter
    Used to distinguish melanomas from benign moles
68
Q

What causes moles?

A

Benign growths of melanocytes

69
Q

What is the dermo-epidermal junction?

A

The area where the basement membrane anchors the epidermis to the underlying dermis

70
Q

What is epidermolysis bullosa?

A

A group of inherited disorders that cause the skin to blister
Remember: “butterfly children”

71
Q

What causes epidermolysis bullosa?

A

Defects in type VII collagen synthesis weakens anchoring at the dermo-epidermal junction

72
Q

What type of connective tissue is the dermis?

A

Dense irregular

73
Q

Which layer gives the skin its resilience?

A

Dermis

74
Q

What is the characteristic structure of the dermis? (Hint: must resist shear in multiple planes.)

A

Basket-weave

75
Q

The dermis consists of ECM and cellular structures. List 6 of its cellular structures.

A
  1. Blood vessels
  2. Lymph vessels
  3. Nerves
  4. Fibroblasts
  5. Adipocytes
  6. Immune cells
76
Q

How are keloids (lumpy scars) formed?

A

Excessive fibroblast activity following wounding

77
Q

What is hyperhidrosis?

A

Excessive sweating

78
Q

Where would you find sebaceous glands?

A

At the base of hair follicles

79
Q

What type of secretion would you find in sebaceous glands?

A

Holocrine

80
Q

What causes acne?

A

Obstruction of sebaceous glands

81
Q

Why is acne more common in the face?

A

Sebaceous glands are large and abundant

82
Q

List 3 triggers for acne.

A
  1. Increased sebum production at puberty
  2. Infection by normally harmless skin bacteria
  3. Abnormal differentiation of sebaceous glands, leading to their obstruction
83
Q

Compare intrinsic and extrinsic aging of the skin.

A

Intrinsic: chronological
Extrinsic: caused by sun exposure

84
Q

What causes solar elastosis?

A

Excess elastic fibre deposition in the dermis due to UV exposure

85
Q

What causes stretch marks?

A

Collagen fibres oriented along stress lines in the dermis

86
Q

What causes hair to stand on end?

A

Contraction of arrector pilli mucles

87
Q

Where would you find eccrine (i.e., merocrine) sweat glands?

A

Most of the skin

88
Q

Where would you find apocrine sweat glands? (Nb apocrine sweat glands use MEROCRINE secretion.)

A

Armpits, nipples, genitals, anus

89
Q

Compare the function of eccrine sweat glands and apocrine sweat glands.

A

Eccrine: thermoregulation
Apocrine: odour production

90
Q

Compare the secretions of eccrine sweat glands and apocrine sweat glands.

A

Eccrine: watery
Apocrine: protein-rich

91
Q

Sweat itself is odorless. How may it cause body odour?

A

Proteins in sweat from apocrine glands are broken down by bacteria on the skin surface, releasing odor

92
Q

What causes port wine stains?

A

Malformed capillaries

93
Q

How might mast cells cause local edema?

A

Release of heparin, histamine, and cytokines increases blood flow to the area

94
Q

What is the effect of allergens on mast cells?

A

Trigger de-granulation, releasing heparin, histamine, and cytokines to launch an immune response

95
Q

Compare urticaria and angioedema.

A

Urticaria: allergic response, edema of the upper dermis
Angioedema: allergic response, edema of the lower dermis

96
Q

What is the effect of leprosy on nerves?

A

Damage and inflammation

97
Q

List 2 causes of diabetic foot ulcers following injury.

A
  1. Damage to nerves impedes SENSATION

2. Damage to vasculature impedes HEALING

98
Q

What are the 4 mechanoreceptors of the skin?

A
  1. Pacinian corpuscles
  2. Meissner’s corpuscles
  3. Ruffini’s corpuscles
  4. Merkel cells
99
Q

What happens in Raynaud’s phenomenon?

A

Cold-induced spasm of arteries blocks blood flow to the fingers and toes

(BMED) TOB 1-5 (8 decks)

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