Skin Flashcards
1
Q
In what ways does the macroscopic structure of human skin vary?
A
NAME?
2
Q
What causes variation in skin colour?
A
- Ethnicity
- Site
- UV
3
Q
What causes variation in skin hairiness?
A
NAME?
4
Q
What areas of the body are hair free?
A
Palms, soles of feet, lips
5
Q
How does body hair vary between sexes?
A
Facial and more profuse body hair growth in men
6
Q
How does hair vary with age?
A
NAME?
7
Q
How does hair vary between ethnicity?
A
NAME?
8
Q
What causes variation in laxity of skin?
A
NAME?
9
Q
What is the importance in variations of macroscopic state of skin?
A
Influence on susceptibility or manifestations of skin disease
10
Q
What is vitiligo?
A
Autoimmune depigmentation
11
Q
What is the importance of ethnicity in vitiligo?
A
More psychosocial impact if affects visible areas of dark-skinned races
12
Q
What is alopecia areata?
A
Autoimmune hair loss
13
Q
What may affect the psychosocial impact of alopecia areata?
A
If it effects scalp, especially in women
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
15
Q
What skin cancers are more common in whites?
A
- Basal cell carcinoma
- Malignant melenoma
16
Q
What is much of skin ageing and wrinkling due to?
A
UV induced injury to dermal and elastin
17
Q
What is the problem with basal cell carcinomas?
A
Relatively benign cancer, but problematic if left because can cause ulcers
18
Q
What is normal human skin made up of?
A
Epidermis and dermis
19
Q
How does the dermis differ from the epidermis?
A
It is much thicker
20
Q
What does the dermis contain?
A
- Blood vessels
- Arrector pilli muscles
- Sweat glands
21
Q
What does the epidermis consist of?
A
- Stratum corneum
- Granular layer
- Prickle cell layer
- Basal layer
22
Q
What does the epidermis have on the surface?
A
Stratum corneum
23
Q
What does the stratum corneum consist of?
A
Layers of dead cells called corneocytes
24
Q
What does the prickle cell layer do?
A
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
