The Structure and Function of the Skin Flashcards

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1
Q

Where is the epidermis?

A

The outer layer

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2
Q

Describe the epidermis

A

Stratified cellular epithelium

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3
Q

Where is the dermis?

A

Beneath the epidermis

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4
Q

Describe the dermis

A

Connective tissue

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5
Q

Where does the epidermis come from and how does it form?

A

Ectoderm cells form a single layer periderm. This gradually increases in layers of cells and the periderm cells cast off

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6
Q

How is the dermis formed?

A

From mesoderm below ectoderm

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7
Q

What are melanocytes

A

Pigment producing cells

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8
Q

Where do melanocytes migrate from

A

The neural crest

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9
Q

What 5 things does the skin consist of?

A
Epidermis
Appendages
Dermo-epidermal junction
Dermis
Sub-cutis
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10
Q

Give 4 examples of Appendages

A

Nails
Hair
Glands
Mucosae

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11
Q

What is the majority of the epidermis made up of and what does it contain?

A

keratinocytes. It contains structural keratins

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12
Q

What are the 4 types of epidermal cell layers

A

Keratin
Granular
Prickle cell
Basal

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13
Q

How is the regulation of epidermal turnover controlled

A

Growth factors
Cell death
Hormones

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14
Q

In what two scenarios is there a loss of control in the epidermal turnover

A

Skin Cancer

Psoriasis

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15
Q

Histologically, what happens to the cells in psoriasis

A

They migrate

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16
Q

Where do keratinocytes migrate from?

A

The basement membrane

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17
Q

How thick is the basal layer

A

One cell thick

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18
Q

What type of cell makes up the basal layer

A

Small cuboidal

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19
Q

What is the main feature of the basal layer

A

It is highly metabolically active

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20
Q

What are there lots of in the prickle cell layer

A

desmosomes (connections)

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21
Q

What connects to desmosomes

A

Intermediate filaments

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22
Q

What is the granular layer made up of

A

2-3 layers of flatter cells

High lipid content

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23
Q

What is unusual about the cells in the granular layer

A

Cell nuclei are lost

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24
Q

What is the main function of the keratin layer

A

To provide a tight waterproof barrier to keep you from losing water

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25
Q

What common skin disease affects keratinocytes and what does it cause?

A

HPV - causes warts

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26
Q

Where are the mucosal membranes in the body

A
Eyes
Mouth
Nose
Genito-urinary tract
Gi tract
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27
Q

What are the 3 other types of epidermal cells

A
Melanocytes (basal & suprabasal)
Langerhans cells (suprabasal)
Merkel cells (basal)
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28
Q

At what stage do melanocytes migrate from the epidermis to the neural crest

A

In the first 3 months of foetal development

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29
Q

What are the organelles called that melanocytes contain

A

Melanosomes

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30
Q

What is the function of melanocytes

A

To convert tyrosine to melanin

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31
Q

What absorbs light

A

Melanin

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32
Q

How are melanosomes transferred to adjacent keratinocyte

A

Via dendrites

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33
Q

What do melanin caps protect?

A

The nuclear DNA in basal cells

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34
Q

What represents an autoimmune disease with loss of melanocytes

A

Vitiligo

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35
Q

What happens in Albinism

A

A genetic partial loss of pigment production

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36
Q

What happens in Nelson’s syndrome

A

Melanin stimulating hormone is produced in excess by the pituitary

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37
Q

What is the function of Langerhans cells

A

Involved in the skin immune system

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38
Q

What is the appearance of Birbeck granules

A

Racket organelles

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39
Q

Where are Merkel cells found

A

Between keratinocytes and nerve fibres

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40
Q

What do Merkel cells act as

A

Mechanoreceptors

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41
Q

Describe Merkel cell cancer

A

Rare
Caused by viral infection
High mortality

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42
Q

What is there always next to a hair follicle

A

Adjacent sebaceous gland

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43
Q

What are the 3 phases of hair follicle growth

A

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

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44
Q

Describe Alopecia areata

A

Autoimmune hair loss

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45
Q

What 3 sections make up the nail plate

A

Ventral
Intermediate
Dorsal

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46
Q

What is the Dermo-epidermal Junction

A

The interface between epidermis and dermis

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47
Q

What does the dermo-epidermal junction play a key role in

A

Epithelial mesenchymal interactions
Support, anchorage, adhesion, growth and differentiation of epidermal cells
Semi-permeable membrane acting as barrier and filter

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48
Q

What are present in the dermo-epidermal junction

A

Lots of proteins, fibrils and keratins

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49
Q

What is an inherited disease of the DEJ?

A

Epidermolysis bullosa

50
Q

What is an acquired disease of the DEJ

A

Pemphigus, pemphigoid, dermatitis herpetiformis

51
Q

What is the difference between inherited and acquired diseases of the DEJ

A

Inherited is due to a mutation in one of the proteins in the DEJ
Axquired is due to auto-antibodies to proteins in DEJ

52
Q

Describe Epidermolysis Bullosa dystrophica

A

Deformity of the hands and feet - the skin fuses as it tries to over heal causing fingers and toes to stick together

53
Q

At what age does Bullous Pemphigoid occur

A

Any age

54
Q

What are the two fibres found in the dermis

A

Collagen and Elastin

55
Q

Name 5 cells found in the dermis

A
fibroblasts
Macrophages
Mast cells
Lymphocytes
Langerhans cells
56
Q

Name the 5 components of the dermis

A
Cells (fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells)
Fibres (collagen and elastin)
Ground substance
Vessels
nerves
57
Q

What do macrophages do?

A

Hunt for antigen presentation

58
Q

What do lymphocytes do

A

Control immune reactions

59
Q

What are 2 risk factors for photoaging

A

UV light and smoking

60
Q

What happens to the collagen in photoaging?

A

Collagen gets depleted

61
Q

Describe the blood supply in the skin

A

Greater than metabolic needs

62
Q

What happens in photoaging

A

Collagen gets depleted

63
Q

How is Bullous Pemphigoid controlled

A

With the use of steroids

64
Q

Name the 5 components of the dermis

A
Cells (fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells)
Fibres (collagen and elastin)
Ground substance
Vessels
nerves
65
Q

What is the main protein in the dermis

A

Collagen

66
Q

What is the function of the fibroblasts

A

To secrete collagen

67
Q

What is the function of macrophages

A

scavengers, antigen presentation

68
Q

What is the function of mast cells

A

Chemical messengers

69
Q

What 2 factors lead to photoaging

A

UV lights and smoking

70
Q

What happens in photoaging

A

Collagen gets depleted

71
Q

Are blocked lymphatics easy or difficult to treat?

A

Difficult

72
Q

Describe the deep vascular plexus

A

It is horizontal

73
Q

What is the term given to the overgrowth of the blood vessel population

A

Angioma

74
Q

Where are angiomas often found

A

The face

75
Q

What are angiomas associated with?

A

Epilepsy

76
Q

What is seen histologically in an angioma

A

Dilated vascular spaces

77
Q

What happens if there is no protein in the blood supply

A

You get oedema

78
Q

What can cause infection in the lower leg

A

Blockage in the lymphatics

79
Q

Are blocked lymphatics easy or difficult to treat?

A

Difficult

80
Q

What are the 2 types of special receptors in the nerves of the skin and what do they do?

A

Pacinian (pressure)

Meissners (vibration)

81
Q

What nervous system supplies the skin

A

The autonomic

82
Q

Where are sebaceious glands found

A

Everywhere but the palms of the hands and soles of the feet

83
Q

What is required for sweat glands to work

A

Motor nerve

84
Q

Where are neurofibromatosis often found

A

Back, spine and brain

85
Q

What is neurofibromatosis

A

Overgrowth of the nerve endings

86
Q

What are the 3 types of skin glands

A

Eccrine
Sebaceous
Apocrine

87
Q

What type of gland works to cool you down

A

Ecrine (sweat)

88
Q

Over activity of which type of gland results in acne

A

Sebaceous

89
Q

What are apocrine sweat glands dependent on

A

Androgen

90
Q

Where are sebaceious glands found

A

Everywhere but the palms of the hands and soles of the feet

91
Q

What are the functions of eccrine glands (3)

A

Cooling by evaporation

Moisten palms/ soles to aid grip

92
Q

What are the main two functions of sebaceous glands

A

Control moisture loss and protect from bacterial and fungal infections

93
Q

What is the main target of the treatment of acne

A

To target the oil gland to stop it secreting as much

94
Q

When does odour occur from sweat

A

After bacterial decomposition

95
Q

How do apocrine sweat glands develop

A

As part of pilosebaceous unit

96
Q

Where are apocrine sweat glands located

A

Axillae and perineum

97
Q

What are apocrine sweat glands dependent on

A

Androgen

98
Q

What occurs in cumulative irritant hand dematitis

A

Extra fluid between epidermal cells which can be seen between vesicle cells

99
Q

What are the functions of eccrine glands (3)

A

Cooling by evaporation

Moisten palms/ soles to aid grip

100
Q

What are the 6 main functions of the skin

A
Barrier
Metabolism and detoxification
thermoregulation
immune defence
communication
sensory functions
101
Q

What is Erythroderma largely made up of

A

Keratin loss or general protein loss (very dry appearance)

102
Q

If the barrier is broken down, what happens

A

Dehydration
Hypoalbuminaemia
Infection

103
Q

What is the 2 way barrier of the skin

A

Epidermis

104
Q

What is the underlying cause of ichthyosis

A

Cholesterol not being properly metabolised

105
Q

What can induce ichthyosis

A

Statins

106
Q

What occurs in cumulative irritant hand dematitis

A

Extra fluid between epidermal cells which can be seen between vesicle cells

107
Q

What happens in frostbite

A

There is so much vasocontstriction that the person has lost tissue

108
Q

Describe the relationship between the wavelength of light and the depth of penetration into skin tissue

A

The longer the wavelength the deeper the penetration - more chance of skin cancer with deeper penetration as it can cause more damage

109
Q

What does melanin do

A

Absorbs UV rays to protect DNA in the cells’ nuclei

110
Q

In which 3 ways is the skin metabolically active

A

Vitamin D metabolism
Thyroid hormone metabolism
Defence against chemicals, drugs, pollutatnts and sunlight

111
Q

What is another name for crusted scabies

A

Norwegian scabies

112
Q

Where does the conversion of Thyroxine T4 to Triiodothyronine T3 occur

A

Mostly (80%) in periphera (to thyroid)l tissues including skin and 20% in the thyroid

113
Q

What does thermoregulation do

A

Protect against being too hot or too cold by controlling sweating, shivering and blood supply

114
Q

What amount of sweat can be produced by 1 person in a day

A

20L

115
Q

What happens in frostbite

A

There is so much vasocontstriction that the person has lost tissue

116
Q

What are the 2 most important cells in the immune defence in the skin

A

Langerhans’ and T cells

117
Q

What are examples of non-specific immune defence responses

A

Itch, localised prickling

118
Q

What are specific responses in immune defence

A

Memory response to some infection that you have previously been exposed to

119
Q

What is another name for crusted scabies

A

Norwegian scabies

120
Q

What is chronic discoid lupus erythematosus

A

An autoimmune disease which is caused by an inappropriate immune response

121
Q

Name some types of sensory functions of the skin

A

Touch, pressure, vibration
Pain and itch
heat and cold
nerve endings and receptors in the skin

122
Q

What condition is often associated with diabetes mellitus

A

Neuropathic ulcer (leprosy)