Skin Flashcards

1
Q

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

A

NAME?

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2
Q

What causes variation in skin colour?

A
  • Ethnicity
  • Site
  • UV
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3
Q

What causes variation in skin hairiness?

A

NAME?

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4
Q

What areas of the body are hair free?

A

Palms, soles of feet, lips

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5
Q

How does body hair vary between sexes?

A

Facial and more profuse body hair growth in men

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6
Q

How does hair vary with age?

A

NAME?

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7
Q

How does hair vary between ethnicity?

A

NAME?

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8
Q

What causes variation in laxity of skin?

A

NAME?

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9
Q

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

A

Influence on susceptibility or manifestations of skin disease

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10
Q

What is vitiligo?

A

Autoimmune depigmentation

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11
Q

What is the importance of ethnicity in vitiligo?

A

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

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12
Q

What is alopecia areata?

A

Autoimmune hair loss

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13
Q

What may affect the psychosocial impact of alopecia areata?

A

If it effects scalp, especially in women

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14
Q

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

A
  • Sunburn doesn’t occur in black skin
  • Skin ageing in whites
  • Skin cancer in whites
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15
Q

What skin cancers are more common in whites?

A
  • Basal cell carcinoma

- Malignant melenoma

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16
Q

What is much of skin ageing and wrinkling due to?

A

UV induced injury to dermal and elastin

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17
Q

What is the problem with basal cell carcinomas?

A

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

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18
Q

What is normal human skin made up of?

A

Epidermis and dermis

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19
Q

How does the dermis differ from the epidermis?

A

It is much thicker

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20
Q

What does the dermis contain?

A
  • Blood vessels
  • Arrector pilli muscles
  • Sweat glands
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21
Q

What does the epidermis consist of?

A
  • Stratum corneum
  • Granular layer
  • Prickle cell layer
  • Basal layer
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22
Q

What does the epidermis have on the surface?

A

Stratum corneum

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23
Q

What does the stratum corneum consist of?

A

Layers of dead cells called corneocytes

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24
Q

What does the prickle cell layer do?

A

Interdigitates with the dermis

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25
Q

What kind of epithelium does the epidermis have?

A

Stratified squamous keratinised epithelium

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26
Q

What is the epidermis mainly made up of?

A

Keratinocytes and their products

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27
Q

What is keratinocytemitosis?

A

Cell division

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28
Q

Where doeskeratinocytemitosis occur?

A

Mainly in the basal cell layer

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29
Q

What happens when daughter keratinocytes?

A

They move upwards to form the prickle cell layer

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30
Q

What happens as daughter keratinocytes move upwards?

A

Terminal differentiation begins

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31
Q

What happens when keratinocytes undergo terminal differentiation?

A

They lose their ability to divide

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32
Q

What to keratinocytes synthesise?

A

Keratins

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33
Q

What are keratins?

A

Heterodimeric fibrous proteins

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34
Q

What do keratins contribute to?

A

The strength of the epidermis

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35
Q

What are keratins the main constituents of?

A

Hair and nails

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36
Q

What joins prickle cells

A

Prickle like desmosomes

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37
Q

What are desmosomes?

A

Intercellular junctions

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38
Q

What are basal keratinocytes full of?

A

Keratin

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39
Q

What happens to basal keratinocytes?

A

They undergo cell division

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40
Q

What abrupt changes occur in the granular layer?

A

NAME?

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41
Q

What are the features of corneocytes?

A

Dead, anucleur

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42
Q

What does the granular layer contain?

A

Keratohyalin

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43
Q

What is keratohyalin?

A

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

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44
Q

What does filaggrin do?

A

Helps aggregate keratin

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45
Q

What does involucrin do?

A

Forms major part of corneocyte envelope

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46
Q

What do the enzymes in keratohyalin do?

A

NAME?

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47
Q

What are enzymes that degrade the phospholipid bilayer called?

A

Phosphore lipase

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48
Q

What is the stratum corneum made up of?

A

Layers of flattened corneocytes

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49
Q

What is the major role of the stratum corneum?

A

Skin barrier formation

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50
Q

What is the barrier function of skin?

A
  • Waterproofing

- Physical and chemical barrier

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51
Q

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

A

30-40 days

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52
Q

What type of cells are melanocytes?

A

Dendritic cells

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53
Q

Where do melanocytes originate from?

A

Neural crest

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54
Q

Where do melanocytes occur?

A

At intervals along the basal layer of the epidermis

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55
Q

When are melanocytes difficult to see?

A

Without special stains

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56
Q

What do melanocytes produce?

A

Melanin

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57
Q

What is melanin?

A

The main pigment that gives skin its colour

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58
Q

How do melanocytes differ in black/tanned skin?

A

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

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59
Q

What kind of cells are Langerhans cells?

A

Dendritic

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60
Q

What is the origin of Langerhans cells?

A

Bone marrow

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61
Q

Where are Langerhans cells found?

A

Scattered through the prickle cell layer

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62
Q

When is it difficult to see Langerhans cells?

A

Without special stains

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63
Q

What is the purpose of Langerhans cells

A

Highly specialised capacity to present antigens to T lymphocytes

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64
Q

What do Langerhans cells mediate?

A

Immune reactions

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65
Q

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

A

S100 monoclonal antibodies stains

66
Q

What happens to mature melanosomes?

A

They are transferred to neighbouring keratinocytes by pigment donation

67
Q

What does pigment donation involve?

A

Phagocytosis of tips of dendritic processes

68
Q

What do we need melanosomes for?

A

To protect DNA

69
Q

Why is it important to protect DNA?

A

So we don’t get cancer

70
Q

What do we need to balance DNA protection with?

A

The need for vitamin D

71
Q

Where do melanosomes come to lie?

A

On the outer side of the cell

72
Q

How does palmar skin differ from normal skin?

A

NAME?

73
Q

How does scalp skin differ from normal skin?

A
  • Hair follicles and sebaceous glands
  • Fat lobules
  • Fibrous septae
74
Q

Give 4 examples of disorders of epidermal components?

A
  • Psoriasis
  • Allergic contact dermatitis
  • Malignant melanoma
  • Vitiligo
75
Q

What is psoriasis?

A

Abnormal epidermal growth and differentiation

76
Q

What % of the population is affected by psoriasis?

A

2%

77
Q

What causes psoriasis?

A

Unknown

78
Q

What proves that psoriasis is influenced by genetic factors?

A

It runs in families

79
Q

What is psoriasis associated with?

A

Extreme proliferation of epidermal basal layer

80
Q

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

A

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

81
Q

How does psoriasis manifest clinically?

A

As excessive scaling

82
Q

What may psoriasis involve?

A

Any area of skin, including the scalp

83
Q

What can the effects of psoriasis be?

A

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

84
Q

When is psoriasis particularly disruptive?

A

When it affects the whole body

85
Q

What is allergic contact dermatitis mediated by?

A

Langerhans cells

86
Q

What are Langerhans cells responsible for?

A

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

87
Q

What causes a malignant melanoma?

A

Malignant growth of melonocytes

88
Q

What do melonocytes do?

A

‘Feed out’ melanin to surrounding keranocytes through dendrites

89
Q

What do melanocytes to with age?

A

Often stop functioning in hair follices

90
Q

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

A

Greying

91
Q

What is a malignant melanoma?

A

An agressive tumour (neoplasm) of melanocytes

92
Q

What is the most common primary site of malignant melanomas?

A

Skin

93
Q

What is associated with good prognosis for malignant melanomas?

A

Retention of the tumour cells above the epidermal basement membrane

94
Q

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

A

Superficial spreading melanoma

95
Q

What is associated with poor prognosis with malignant melanomas?

A

More penetrating, ‘modular’ melanomas

96
Q

What are common moles?

A

Benign growths of melanocytes

97
Q

When are moles concerning?

A

When they have irregular colouration or an irregular surface

98
Q

What is vitiligo?

A

An autoimmune disease in which immune system attacks melanocytes

99
Q

How does vitiligo usually present?

A

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

100
Q

Where is vitiligo more visible?

A

In dark skin

101
Q

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

A

Could be that the process is under neural control

102
Q

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

A

Melanocytes are derived embryologically from the neural crest

103
Q

Where is the dermo-epidermal junction?

A

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

104
Q

What are the features of the dermis?

A

Tough, fibrous and vascular layer

105
Q

What makes up the main part of the dermis?

A

Extracellular matrix

106
Q

What does the dermis extracellular matrix contain?

A
  • Collagens, especially type I
  • Elastin
  • Other extracellular matrix components
107
Q

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

A
  • Blood vessels
  • Lymphatic vessels
  • Mast cells
  • Nerves
108
Q

What forms of damage to collagen and elastin are there?

A

NAME?

109
Q

What causes solar elastosis?

A

Excessive UV exposure

110
Q

What are stretch marks also known as?

A

Striae

111
Q

What follows wounding?

A

Scars

112
Q

What do scars compose of?

A

Main collagen synthesised by fibroblasts

113
Q

What results from grossly excessive scar tissue production?

A

Kelloids

114
Q

What type of blood vessels are there in the skin?

A
  • Smaller blood vessels in superficial dermis- mainly capillaries, small venules and arterioles
  • Interconnecting vesicles
  • Larger blood vessels in deeper dermis
115
Q

Give an example of a birthmark

A

Port wine stain

116
Q

What causes a port wine stain?

A

Congenital malformation of blood vessels

117
Q

How are tissue mast cells distributed in skin?

A

Around dermal blood vessels

118
Q

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

A

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

119
Q

What is oedema?

A

Swelling due to increased tissue fluid

120
Q

What is the result of local oedema in the skin?

A

Causes urticaria and angio-oedema

121
Q

Where may the release of histamine have serious consequences?

A

In vital structures such as the upper respiratory tract

122
Q

Where are cutaneous sensory nerves of critical importance?

A

In transmitting sensation

123
Q

Give 4 skin appendages

A
  • Hair follicles
  • Sebaceous glands
  • Sweat glands
  • Nails
124
Q

What do the hair follicles and the sebaceous glands form?

A

Pilosebaceous units

125
Q

What kind of sweat glands are there?

A
  • Ecrine

- Aprocrine

126
Q

Describe the structure of a pilosebaceous unit?

A

NAME?

127
Q

What is the hair sheath?

A

The projection of epidermis surrounding the hair follicle

128
Q

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

A

The are large and produce sebum

129
Q

What do sebaceous gland ducts lead to?

A

Hair follicles

130
Q

How do sebaceous glands secrete?

A

Holocrine secretion

131
Q

What is acne?

A

A skin disease affecting sebaceous glands

132
Q

What causes acne?

A

NAME?

133
Q

When do the changes in sebaceous glands causing acne occur?

A

Puberty

134
Q

Where are sebaceous glands most abundant?

A

On face

135
Q

What is hyperhidrosis?

A

Increased sweating

136
Q

What causes hyperhidrosis?

A

Usually unknown

137
Q

What may hyperhidrosis exclusively affect?

A

Palms and soles

138
Q

Why is hyperhidrosis often a substantial problem?

A

NAME?

139
Q

How big are apocrine sweat glands?

A

Large

140
Q

Where are apocrine sweat glands most abundant?

A

Axillae, genital and submammary areas

141
Q

What is the functional value of apocrine sweat glands?

A

None

142
Q

What do apocine sweat glands produce?

A

Odourless, protein rich, apocrine secretion

143
Q

What digests the secretions of apocrine sweat glands?

A

Cutaneous microbes

144
Q

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

A

Body odour

145
Q

What are the main functions of skin?

A
  • Barrier function
  • Sensation
  • Thermoregulation
  • Psychosexual communication
146
Q

What forms the major barrier function of skin?

A

The stratum corneum

147
Q

What does the stratum corneum form?

A

Major barrier preventing percutaneous absorption of exogenous substances

148
Q

When must the skin barrier be overcome?

A

During percutaneous administration of drugs

149
Q

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

A

Diseases such as widespread scaling rashes

150
Q

What does poor barrier function of skin lead to?

A

NAME?

151
Q

When may skin sensation be lost?

A

NAME?

152
Q

What is critically important in maintenance of body temperature?

A

NAME?

153
Q

What may happen if thermoregulation fails?

A

Serious consequences

154
Q

What happens in vascular thermoregulation?

A

NAME?

155
Q

What does dilation of skin blood vessels lead to?

A

Heat loss

156
Q

What does constriction of skin blood vessels lead to?

A
  • Heat conservation

- Pallor

157
Q

What may cause a failure of vascular thermoregulation?

A
  • Widespread vasodilation of erythyrodermic psoriasis

- Inability to vasoconstrict in a cold environment

158
Q

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

A

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

159
Q

How does thermoregulation by eccrine sweating work?

A

Evaporation of eccrine sweat causing cooling

160
Q

How can skin be used for psychosocial communication?

A

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