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Z OLD Tissues of the Body > Skin > Flashcards

Flashcards in Skin Deck (160):
1

In what ways does the macroscopic structure of human skin vary?

#NAME?

2

What causes variation in skin colour?

- Ethnicity 
- Site
- UV

3

What causes variation in skin hairiness?

#NAME?

4

What areas of the body are hair free?

Palms, soles of feet, lips

5

How does body hair vary between sexes?

Facial and more profuse body hair growth in men

6

How does hair vary with age?

#NAME?

7

How does hair vary between ethnicity?

#NAME?

8

What causes variation in laxity of skin?

#NAME?

9

What is the importance in variations of macroscopic state of skin?

Influence on susceptibility or manifestations of skin disease

10

What is vitiligo?

Autoimmune depigmentation

11

What is the importance of ethnicity in vitiligo?

More psychosocial impact if affects visible areas of dark-skinned races

12

What is alopecia areata?

Autoimmune hair loss

13

What may affect the psychosocial impact of alopecia areata?

If it effects scalp, especially in women

14

How does the affect of UV-induced abnormalities differ between different skin types?

- Sunburn doesn’t occur in black skin
- Skin ageing in whites
- Skin cancer in whites

15

What skin cancers are more common in whites?

- Basal cell carcinoma 
- Malignant melenoma

16

What is much of skin ageing and wrinkling due to?

UV induced injury to dermal and elastin

17

What is the problem with basal cell carcinomas?

Relatively benign cancer, but problematic if left because can cause ulcers

18

What is normal human skin made up of?

Epidermis and dermis

19

How does the dermis differ from the epidermis?

It is much thicker

20

What does the dermis contain?

- Blood vessels
- Arrector pilli muscles 
- Sweat glands

21

What does the epidermis consist of?

- Stratum corneum 
- Granular layer
- Prickle cell layer
- Basal layer

22

What does the epidermis have on the surface?

Stratum corneum

23

What does the stratum corneum consist of?

Layers of dead cells called corneocytes

24

What does the prickle cell layer do?

Interdigitates with the dermis

25

What kind of epithelium does the epidermis have?

Stratified squamous keratinised epithelium

26

What is the epidermis mainly made up of?

Keratinocytes and their products

27

What is keratinocytemitosis?

Cell division

28

Where does keratinocytemitosis occur?

Mainly in the basal cell layer

29

What happens when daughter keratinocytes?

They move upwards to form the prickle cell layer

30

What happens as daughter keratinocytes move upwards?

Terminal differentiation begins

31

What happens when keratinocytes undergo terminal differentiation?

They lose their ability to divide

32

What to keratinocytes synthesise?

Keratins

33

What are keratins?

Heterodimeric fibrous proteins

34

What do keratins contribute to?

The strength of the epidermis

35

What are keratins the main constituents of?

Hair and nails

36

What joins prickle cells

Prickle like desmosomes

37

What are desmosomes?

Intercellular junctions

38

What are basal keratinocytes full of?

Keratin

39

What happens to basal keratinocytes?

They undergo cell division

40

What abrupt changes occur in the granular layer?

#NAME?

41

What are the features of corneocytes?

Dead, anucleur

42

What does the granular layer contain?

Keratohyalin

43

What is keratohyalin?

Aggregations of keratins, other fibrous proteins (e.g. filaggrin, involucrin) and enzymes

44

What does filaggrin do?

Helps aggregate keratin

45

What does involucrin do?

Forms major part of corneocyte envelope

46

What do the enzymes in keratohyalin do?

#NAME?

47

What are enzymes that degrade the phospholipid bilayer called?

Phosphore lipase

48

What is the stratum corneum made up of?

Layers of flattened corneocytes

49

What is the major role of the stratum corneum?

Skin barrier formation

50

What is the barrier function of skin?

- Waterproofing 
- Physical and chemical barrier

51

What is the transit time of a keranocyte from the basal layer to the stratum corneum?

30-40 days

52

What type of cells are melanocytes?

Dendritic cells

53

Where do melanocytes originate from?

Neural crest

54

Where do melanocytes occur?

At intervals along the basal layer of the epidermis

55

When are melanocytes difficult to see?

Without special stains

56

What do melanocytes produce?

Melanin

57

What is melanin?

The main pigment that gives skin its colour

58

How do melanocytes differ in black/tanned skin?

They produce more melanin, but not an increased number of melanocytes

59

What kind of cells are Langerhans cells?

Dendritic

60

What is the origin of Langerhans cells?

Bone marrow

61

Where are Langerhans cells found?

Scattered through the prickle cell layer

62

When is it difficult to see Langerhans cells?

Without special stains

63

What is the purpose of Langerhans cells

Highly specialised capacity to present antigens to T lymphocytes

64

What do Langerhans cells mediate?

Immune reactions

65

Give an example of a stain that is used to show Langerhans cells and melanocytes?

S100 monoclonal antibodies stains

66

What happens to mature melanosomes?

They are transferred to neighbouring keratinocytes by pigment donation

67

What does pigment donation involve?

Phagocytosis of tips of dendritic processes

68

What do we need melanosomes for?

To protect DNA

69

Why is it important to protect DNA?

So we don’t get cancer

70

What do we need to balance DNA protection with?

The need for vitamin D

71

Where do melanosomes come to lie?

On the outer side of the cell

72

How does palmar skin differ from normal skin?

#NAME?

73

How does scalp skin differ from normal skin?

- Hair follicles and sebaceous glands
- Fat lobules 
- Fibrous septae

74

Give 4 examples of disorders of epidermal components?

- Psoriasis 
- Allergic contact dermatitis 
- Malignant melanoma 
- Vitiligo

75

What is psoriasis?

Abnormal epidermal growth and differentiation

76

What % of the population is affected by psoriasis?

2%

77

What causes psoriasis?

Unknown

78

What proves that psoriasis is influenced by genetic factors?

It runs in families

79

What is psoriasis associated with?

Extreme proliferation of epidermal basal layer

80

What does the extreme proliferation of the epidermal basal layer cause?

Gross thickening of prickle cell layer and production of excessive stratum corneum cells

81

How does psoriasis manifest clinically?

As excessive scaling

82

What may psoriasis involve?

Any area of skin, including the scalp

83

What can the effects of psoriasis be?

Depending on severity, can have severe effects on quality of life, general health, occupation etc

84

When is psoriasis particularly disruptive?

When it affects the whole body

85

What is allergic contact dermatitis mediated by?

Langerhans cells

86

What are Langerhans cells responsible for?

Presentation of antigens to T lymphocytes and for cutaneous delayed-type hypersensitivity reactions

87

What causes a malignant melanoma?

Malignant growth of melonocytes

88

What do melonocytes do?

‘Feed out’ melanin to surrounding keranocytes through dendrites

89

What do melanocytes to with age?

Often stop functioning in hair follices

90

What is the result of cessation of function of melanocytes in hair follicles?

Greying

91

What is a malignant melanoma?

An agressive tumour (neoplasm) of melanocytes

92

What is the most common primary site of malignant melanomas?

Skin

93

What is associated with good prognosis for malignant melanomas?

Retention of the tumour cells above the epidermal basement membrane

94

What is it called when the malignant melanoma is retained above the epidermal basement membrane?

Superficial spreading melanoma

95

What is associated with poor prognosis with malignant melanomas?

More penetrating, ‘modular’ melanomas

96

What are common moles?

Benign growths of melanocytes

97

When are moles concerning?

When they have irregular colouration or an irregular surface

98

What is vitiligo?

An autoimmune disease in which immune system attacks melanocytes

99

How does vitiligo usually present?

In symmetrical, localised areas of skin, causing well-demarcated depigmentation

100

Where is vitiligo more visible?

In dark skin

101

What could be the cause of the symmetrical pattern of vitiligo?

Could be that the process is under neural control

102

Why would it make sense that vitiligo is under neural control?

Melanocytes are derived embryologically from the neural crest

103

Where is the dermo-epidermal junction?

The basement membrane zone, below the basal layer of the epidermis

104

What are the features of the dermis?

Tough, fibrous and vascular layer

105

What makes up the main part of the dermis?

Extracellular matrix

106

What does the dermis extracellular matrix contain?

- Collagens, especially type I 
- Elastin
- Other extracellular matrix components

107

Other than extracellular matrix, what are the other dermal components?

- Blood vessels
- Lymphatic vessels 
- Mast cells 
- Nerves

108

What forms of damage to collagen and elastin are there?

#NAME?

109

What causes solar elastosis?

Excessive UV exposure

110

What are stretch marks also known as?

Striae

111

What follows wounding?

Scars

112

What do scars compose of?

Main collagen synthesised by fibroblasts

113

What results from grossly excessive scar tissue production?

Kelloids

114

What type of blood vessels are there in the skin?

- Smaller blood vessels in superficial dermis- mainly capillaries, small venules and arterioles
- Interconnecting vesicles 
- Larger blood vessels in deeper dermis

115

Give an example of a birthmark

Port wine stain

116

What causes a port wine stain?

Congenital malformation of blood vessels

117

How are tissue mast cells distributed in skin?

Around dermal blood vessels

118

What is the result of the release of histamine from mast cells?

Causes increased vascular permeability and leakage of plasma into extravascular sites, causing local oedema

119

What is oedema?

Swelling due to increased tissue fluid

120

What is the result of local oedema in the skin?

Causes urticaria and angio-oedema

121

Where may the release of histamine have serious consequences?

In vital structures such as the upper respiratory tract

122

Where are cutaneous sensory nerves of critical importance?

In transmitting sensation

123

Give 4 skin appendages

- Hair follicles 
- Sebaceous glands
- Sweat glands
- Nails

124

What do the hair follicles and the sebaceous glands form?

Pilosebaceous units

125

What kind of sweat glands are there?

- Ecrine 
- Aprocrine

126

Describe the structure of a pilosebaceous unit?

#NAME?

127

What is the hair sheath?

The projection of epidermis surrounding the hair follicle

128

What is typically true of sebaceous glands in the adult human face?

The are large and produce sebum

129

What do sebaceous gland ducts lead to?

Hair follicles

130

How do sebaceous glands secrete?

Holocrine secretion

131

What is acne?

A skin disease affecting sebaceous glands

132

What causes acne?

#NAME?

133

When do the changes in sebaceous glands causing acne occur?

Puberty

134

Where are sebaceous glands most abundant?

On face

135

What is hyperhidrosis?

Increased sweating

136

What causes hyperhidrosis?

Usually unknown

137

What may hyperhidrosis exclusively affect?

Palms and soles

138

Why is hyperhidrosis often a substantial problem?

#NAME?

139

How big are apocrine sweat glands?

Large

140

Where are apocrine sweat glands most abundant?

Axillae, genital and submammary areas

141

What is the functional value of apocrine sweat glands?

None

142

What do apocine sweat glands produce?

Odourless, protein rich, apocrine secretion

143

What digests the secretions of apocrine sweat glands?

Cutaneous microbes

144

What is the result of the digestion of the secretion of apocrine sweat glands?

Body odour

145

What are the main functions of skin?

- Barrier function 
- Sensation 
- Thermoregulation 
- Psychosexual communication

146

What forms the major barrier function of skin?

The stratum corneum

147

What does the stratum corneum form?

Major barrier preventing percutaneous absorption of exogenous substances

148

When must the skin barrier be overcome?

During percutaneous administration of drugs

149

When may be the barrier function of skin be seriously disrupted?

Diseases such as widespread scaling rashes

150

What does poor barrier function of skin lead to?

#NAME?

151

When may skin sensation be lost?

#NAME?

152

What is critically important in maintenance of body temperature?

#NAME?

153

What may happen if thermoregulation fails?

Serious consequences

154

What happens in vascular thermoregulation?

#NAME?

155

What does dilation of skin blood vessels lead to?

Heat loss

156

What does constriction of skin blood vessels lead to?

- Heat conservation 
- Pallor

157

What may cause a failure of vascular thermoregulation?

- Widespread vasodilation of erythyrodermic psoriasis 
- Inability to vasoconstrict in a cold environment

158

What may be the result of failure to vasoconstrict in a cold environment?

Leads to heat loss, causing the patient to become shivery and potentially hypothermic

159

How does thermoregulation by eccrine sweating work?

Evaporation of eccrine sweat causing cooling

160

How can skin be used for psychosocial communication?

The skin itself and its appendages can be manipulated in many ways as a means of communication and expression