Week 1 Flashcards
(195 cards)
1
Q
What is the outer layer of skin and what is its cell type?
A
Epidermis
Stratified cellular epithelium
2
Q
What layer is beneath the epidermis and what cell type is it?
A
Dermis
Connective tissue
3
Q
What skin layer is described - Ectoderm cells form single layer periderm, gradual increase in layers of cells and periderm cells cast off?
A
Epidermis
4
Q
What is the dermis formed from?
A
Mesoderm below the ectoderm
5
Q
What are pigment producing cells from neural crest?
A
Melanocytes
6
Q
What are developmental growth patterns of skin - not following vessels, nerves or lymphatics?
A
Blaschko’s lines
7
Q
Name four skin appendages?
A
- Nail
- Hair
- Glands
- Mucosae
8
Q
What makes up skin and is predominantly fat?
A
Sub-cutis
9
Q
Does the skin consist of dermo-epidermal junctions?
A
Yes
10
Q
What is stratified squamosu epithelium, 1.5mm thick?
A
Epidermis
11
Q
What is 95% of the epidermis?
A
Keratinocytes
12
Q
What do keratinocytes contain?
A
Structural keratins
13
Q
What are three other cell types in the epidermis?
A
Melanocytes (basal and suprabasal) Langerhans cells (suprabasal) Merkel cells (basal)
14
Q
What are the four epidermal cell layers?
A
- Keratin layer
- Granular layer
- Prickle cell layer
- Basal layer
15
Q
What three factors control regulation of epidermal turnover?
A
Growth factors
Cell death
Hormones
16
Q
Name two situations where regulation of epidermal turnover is lost?
A
Skin cancer and psoriasis
17
Q
What takes 28 days and involves keratinocytes migrating from basement membrane as well as continuous regeneration of epidermis?
A
Differentiation
18
Q
What layer is usually one cell thick and small cuboidal?
A
Basal layer
19
Q
The basal layer is highly metabolically active and has lots of what substance?
A
Intermediate filaments (keratin)
20
Q
What layer has larger polyhedral cells?
A
Prickle cell layer
21
Q
In the prickle cell layer there are lots of desmosomes - what connects to them?
A
Intermediate filaments
22
Q
What layers does the granular layer consist of?
A
2-3 layers of flatter cells
23
Q
What layer contains large keratohyalin granules?
A
Granular layer
24
Q
What contains structural filaggrin and involucrin proteins and is present in the granular layer?
A
Large keratohyalin granules
25
What layer has odland bodies, high lipid content, cell nuclei lost and is the origin of "cornified envelope"?
Granular layer
26
What are overlapping non-nucleated cell remnants called and what layer do they occur in?
Corneocytes
| Keratin layer
27
What makes up 80% of the keratin layer?
Keratin and filaggrin
28
What do lamellar granules release in the keratin layer?
Lipids
29
What layer is a tight waterproof barrier?
Keratin layer
30
What mucosa is present in lacrimal glands, eye lashes and sebaceous glands?
Ocular mucosa
31
Where do melanocytes migrate to in the first 3 months of foetal development?
From the epidermis to neural crest
32
What are pigment producing dendritic cells?
Melanocytes
33
What are the organelles in melanocytes called?
Melanosomes
34
What are the two types of melanin pigment made from tyrosine by melanocytes?
1. Eumelanin (brown or black)
| 2. Phaeomelanin (red or yellow)
35
Does melanin absorb light?
Yes - neutral density filter
36
How are full melanosomes transferred to adjacent keratinocytes?
Via desmosomes
37
What do melanocytes form a protective cap over?
Nucleus
38
What represents an autoimmune disease with loss of melanocytes?
Vitiligo
39
In what disorder is there a genetic partial loss of pigment production?
Albinism
40
What disorder involves melanin stimulating hormone produced in excess by the pituitary gland?
Neslons Syndrome
41
What is a tumour of the melanocyte cell line?
Malignant melanoma
42
What cells come from mesenchymal origin - bone marrow?
Langerhans cells
43
What level are Langerhans cells found in?
Prickle cell level in epidermis - also found in dermis and lymph nodes
44
What cells found in the prickle cell level are antigen presenting cells?
Langerhans cells
45
What cells are basal, between keratinocytes and nerve fibres and act as mechanoreceptors?
Merkel cells
46
What type of infection is merkel cell cancer caused by?
Viral
47
What appendages have adjacent sebaceous glands?
Hair follicles
48
Hair pigmentation occurs via what?
Melanocytes above dermal papilla
49
What are the three phases of hair follicles growth?
Anagen - growing
Catagen - involuting
Telogen - resting
50
Name a hormone that influences hair growth?
Thyroxine
51
What are the three types of hair follicles?
Lanugo (in utero), vellus, terminal
52
What phase of hair follicles growth is the shedding phase?
Telogen
53
In humans what is the telogen phase?
Asynchronus
54
What is the interface between the epidermis and dermis called? It also has a key role in epithelial-mesenchymal interactions including support, anchorage, adhesion, growth and differentiation of epidermal cells. Also semi-permeable membrane acting as a barrier and filter.
Dermo-epidermal junction
55
What are inherited skin fragility diseases of the DEJ due to?
Mutation in one of the proteins in the DEJ.
56
Name three acquired (auto-antibodies to proteins in DEJ) diseases of the DEJ.
1. Pemphigus
2. Pemphigoid
3. Dermatitis herpetiformis
57
Name two inherited skin fragility.
Epidermolysis Bullosa simplex
| Epidermolysis Bullosa dystrophica
58
Name an acquired blistering disorder?
Bullous pemphigoid
59
What are these cells components of: mainly fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells?
Dermis
60
What two fibres make up the dermis?
Collagen and elastin
61
Is ground substance present in the dermis?
Yes
62
What do fibroblasts secrete?
Collagen
63
Name some cells in the dermis which antigen present?
Langerhans cells
64
Name the cells in the dermis which are chemical messengers?
Mast cells
65
What substance do mucopolysaccharides and glycosaminoglycans make up in the dermis?
Ground substance
66
Are the blood vessels in horizontal or vertical plexi?
Horizontal
67
Name a condition caused by localised overgrowth of blood vessels?
Port wine stain "stone marks" (capillary or cavernous haemangiomas)
68
What do smaller non-contractile lymphatic vessels lead to?
Larger contractile lymphatic trunks
69
What gives continuous drainage of plasma proteins, extravasated cells and excess interstitial fluid?
Lymphatic vessels
70
What do the special receptors pacinian and Meissners corpuscles detect?
Pressure and vibration
71
What are the three types of skin glands?
1. Eccrine gland
2. Sebaceous gland
3. Apocrine gland
72
Where are the largest sebaceous glands present?
On the face and chest
73
What four things make up sebum?
Squalene, wax esters, triglycerides and free fatty acids
74
What produces sebum?
Sebaceous glands
75
Give two functions of sebaceous glands?
Controls moisture loss and protects against bacterial and fungal infection
76
What occurs as a result of increased sebum, blocked ducts and bacterial activity?
Acne
77
What do apocrine sweat glands develop as a part of?
Pilosebaceous unit
78
In what two locations are apocrine sweat glands found?
Axillae and perineum
79
What type of sweat glands are androgen dependent?
Apocrine
80
Where are eccrine sweat glands found?
On the whole skin surface (palms, soles and axillae in particular)
81
What is the nerve supply to the eccrine sweat glands?
Sympathetic cholinergic nerve supply - mental, thermal and gustatory stimulation
82
Give a function of eccrine sweat glands?
Cooling by evaporation
83
Name an acute skin failure?
Toxic epidermal necrolysis
84
What skin failure involves red skin all over?
Erythroderma
85
What can protein loss lead to?
Hypoalbuminaemia
86
What absorbs UV rays to protect DNA in the cells nuclei?
Melanin
87
Give two metabolism processes that take place in the skin?
Vitamin D metabolism
| Thyroid hormone metabolism
88
In vitamin D metabolism: what is cholecalciferol (7-dehydrocholesterol) converted to by UV?
Vitamin D3
89
What is vitamin D3 stored as in the liver and what is it then converted to in the kidney?
Hydroxycholecalciferol
| 1,25-dihydroxycholecaliferol
90
During metabolism of thyroid hormone: what is thyroxine (T4) converted to?
Triiodothyronine (T3)
91
Where does the majority of T4 to T3 conversion take place?
20% in thyroid gland and 80% in peripheral tissues including skin
92
What is the term for disseminated herpes simplex virus?
Eczema herpeticum
93
What type of disease is chronic discoid lupus erythematosus?
An autoimmune disease
94
Name four chemical signals/molecules that influence cell behaviour or help target pathogens?
1. Cytokines
2. Chemokines
3. Eicosanoids
4. Antimicrobial peptides
95
What is usually a protein/peptide or polysaccharide thast elicits an immune response?
Antigen
96
Are Langerhans cells an example of adaptive or innate immunity?
Innate
97
What is formed by terminal differentiation of keratinocytes to corneocytes?
Keratin layer
98
Name 3 important structural proteins in the keratin layer and epidermis?
1. Filaggrin
2. Involucrin
3. Keratin
99
What is the Stratum Corneum?
Keratin layer
100
What are the structural and functional cells of the epidermis?
Keratinocytes
101
What can keratinocytes be activated by?
UV light and sensitisers - e.g. allergic contact dermatitis
102
Give three immunological abilities of keratinocytes?
1. Sense pathogens via cell surface receptors
2. Produce antimicrobial peptides
3. Produce cytokines and chemokines
103
What is the type of dendritic cell that intersperses with keratinocytes in the epidermis?
Langerhans cels
104
Name antigen presenting cells characterised by the Birbeck granule (tennis racket)?
Langerhans cells
105
What do langerhans cells act as in the epidermis?
Sentinels
106
What does healthy skin contain a large number of in both the epidermis and dermis?
T cells
107
What T cells are mainly found in the epidermis?
CD8+
108
What T cells are found in the dermis?
CD4+ and CD8+
109
What CD4 cells associated with inflammation are related to psoriasis?
TH1
110
What CD4 cells associated with inflammation are related to atopic dermatitis?
TH2
111
Where are T cells produced?
Bone marrow
112
Where are T cells sensitised?
Thymus
113
What are TH1, IL2 and IFNg?
CD4 helper T cells
114
What two dendritic cells are found in the dermis?
Dermal - involved in Ag presenting and secretng cyto/chemokines
Plasmacytoid - produce IFNa (found in diseased skin)
115
What chromosome is related to MHC?
6
116
What do psoriasis, atopic dermatitis, bullous pemphigoid, contact dermatitis, morphea/systemic sclerosis, urticaria nad systemic lupus erythematosus all have in common?
Skin conditions associated inappropriate immune response/inflammation.
117
How is psoriasis triggered?
By environmental factors in genetically susceptible individuals
118
Psoriasis: immunopathogenesis - when keratinocytes are under stress what do they release?
Factors that stimulate pDC to produce IFNa and they release IL-1B/IL-6 and TNF
119
Psoriasis: immunopathogenesis - once chemical signals activate DC, which migrate to skin draining lymph node to present to and activate T cells, what T cells are affected?
TH1 and TH17
120
Psoriasis:immunopathogenesis - when T cells are attracted to the dermis by chemokines what do they secrete?
IL-17A/17F/22
121
Psoriasis: immunopathogenesis - what does secretion of IL-17A/17F/22 stimulate?
Keratinocyte proliferation, antimicrobial peptide release and neutrophil attracting chemokines
122
When dermal fibroblasts become involved in psoriasis immunopathogenesis - hwat to the release?
Keratinocytes and epidermal growth factors
123
Is atopic eczema histologically different from psoriasis?
Yes
124
Give two examples of impairment of skin barrier function in atopic eczema?
1. Mutations in fillagrin gene associated with severe onset disease
2. Decreased antimicrobial peptides in skin
125
What T cells along with dendritic cells, keratinocytes, macrophages and mast cells are involved in the lesions in atopic eczema?
TH2
126
What antibody is involved in type I immediate hypersensitvity?
IgE
127
What antibodies mediate type II and III hypersensitivity?
IgG and IgM
128
What does skin testing in type III hypersensitivity lead to?
Arthus reaction
129
What cells mediate type IV hypersensitivity?
TH1
130
Name the non-immune cells in the epidermis?
Keratinocytes
131
Name the immune cells in the epidermis?
Langerhans cells and T cells
132
Name the 4 dermis immune cells?
1. Dendritic cells
2. Macrophages
3. T cells
4. NK cells
133
What is a common target for idiosyncratic drug reactions?
Skin
134
Name a type I anaphylactic reaction to the skin?
Urticaria
135
Name two type II cytotoxic reactions to the skin?
Pemphigus and pemphigoid
136
Name a type III immune-complex mediated reaction?
Purpura/rash
137
Name a type IV cell-mediated delayed hypersensitivity reaction?
T-cell mediated erythema/rash
138
Which can be dose dependent - non-immunologically mediated reactions or immunologically mediated reactions?
Non-immunologically mediated reactions
139
What type of reactions are eczema, drug-induced alopecia, phototoxicity, skin erosion or atrophy from topically applied 5-fluorouracil or steroids, psoriasis, pigmentation and cheilitis/xerosis?
Non-immunologically mediated reactions
140
What are the three most common morphologies for skin reactions?
Exanthematous
Morbilliform
Maculopapular
141
Which are more likely to develop drug eruptions - females or males?
Females
142
Name a concomitant disease for development of drug eruptions>
Cystic fibrosis
143
Name two chemical risk factors for drugs involved in eruptions?
1. B-lactam compounds, NSAIDS
| 2. High molecular weight/hapten-forming drugs
144
Name the most common, idiosyncratic, T-cell mediated delayed type hypersensitivity type IV reaction?
Exanthematous drug eruptions
145
What is usually seen with an exanthematous drug eruption?
Widespread symmetrically distributed rash - mucous membranes usually spared
146
With an exanthematous drug eruption: what are involvement of mucous membrane and face, facial oedema & erythema, confluent erythema, fever, blisters, purpura, necrosis, lympjadenopathy, arthralgia and shortness of breath all indicators of?
A potential severe reaction
147
What are penicillins, sulphonamide antibiotics, erythromycin, streptomycin, allopurinol, anti-epileptics: carbamazepine, NSAIDs, phenytoin and chloramphenicol all associated with?
Exanthematous drug eruptions
148
What is the usual type of urticarial drug reaction called?
IgE mediated hypersensitivity type I (carbazepine)
149
Give two examples of pustular/bullous drug eruptions?
1. Acne
| 2. Acute generalised exanthematous pustulosis (AGEP)
150
Give four drugs that can cause acne?
1. Glucocorticoids
2. Androgens
3. Lithium
4. Isoniazid
151
Give three drugs that can cause AGEP?
1. Antibiotics
2. Calcium channel blockers
3. Antimalarials
152
What pustular/bullous drug eruption can be caused by ACE inhibitors, penicillin and furosemide?
Drug-induced bullous pemphigoid
153
What drug can trigger linear IgA disease?
Vancomycin
154
What kind of drug eruption causes well demarcated round/ovoid plaques, red and painful that occur on hands, genitalia, lips and oral mucosa?
Fixed
155
Name four drugs associated with fixed drug eruptions?
1. Tetracycline, doxycycline
2. Paracetamol
3. NSAIDS
4. Carbamazepine
156
Give four examples of severe cutaneous adverse reactions?
1. Stevens-Johnson syndrome
2. Toxic epidermal necrolysis
3. Drug reaction with eosinophilia and systemic symptoms (DRESS)
4. Acute generalised exanthematous pustulosis (AGEP)
157
What severe cutaneous adverse reactions can tramadol, pantoprazole, phenytoin, carbamazepine, cephalosporins and sulfonamide antibiotics cause?
SJS
| TEN
158
What type of reaction is skin toxicity, systemic toxicity and photodegradation?
Acute phototoxic drug reactions
159
Give three chronic phototoxic drug reactions?
Pigmentation, photoageing and photocarcinogenesis
160
Give the definition of phototoxic cutaneous drug reactions
Non-immunological mediated skin reaction which will arise in any individual providing there is enough photo-reactive drug and the appropriate wavelength of light.
161
Can immunosuppression cause increased sensitivity to light?
Yes
162
What are the major patterns of cutaneous phototoxicity caused by chlorpromazine and amiodarone?
Immediate prickling with delayed erythema and pigmentation.
163
What are the major patterns of cutaneous phototoxicity caused by quinine, thiazides and DCMT?
Exaggerated sunburn
164
What are the major patterns of cutaneous phototoxicity caused by calcium channel antagonists?
Exposed telangiectasia
165
What are the major patterns of cutaneous phototoxicity caused by psoralens?
Delayed 3-5 days erythema and pigmentation
166
What are the major patterns of cutaneous phototoxicity caused by nalidixic acid, tetracycline naproxen and amiodarone?
Increased skin fragility
167
What is skin testing not indicated for?
Serum sickness reactions (type III) or for T-cell mediated reactions (type IV) and can potentially trigger SJS, TEN and DRESS.
168
What are two hardening methods for photosensitivity?
Phototherapy and PUVA
169
What can chromophore removal be used for?
Treating photosensitivity
170
Give the normal metabolite pathway for pophyrias?
Glycine + Succinyl coA forms ALA > PBG > HMB > URO > COPRO > PROTO > HAEM
171
Give the four main groups of porphyrias?
1. Phototoxic skin porphyrias (such as erythropoietic protoporphyria)
2. Blsitering and fragility skin porphyrias
3. Acute attack porphyria
4. Severe congenital porphyrias
172
List the three most common skin porphyrias in Scotland?
1. Porphyria cutanea tarda
2. Erythropoietic protoporphyria
3. Variegate porphyria
173
What enzyme is involved in porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
174
Where is porphyria cutanea tarda blisters most commonly seen?
Backs of hands
175
Give four presentations of porphyria cutanea tarda other than fragility and blisters?
1. Hyperpigmentation
2. Hypertrichosis
3. Solar urticaria
4. Morphoea
176
What are four possible underlying causes of Porphyria cutanea tardas?
1. Alcohol
2. Viral hepatitis
3. Oestrogens
4. Haemochromatosis
177
What is the enzyme involved in erythropoietic protoporphyria?
Ferrochelatase
178
What are quantative RBC porphyrins, fluorocytes, transaminases, red cell indices all investiagtions for?
Erythropoietic protoporphyria
179
Give three management options other than behavioural for erythropoietic protoporphyria?
1. Prophylactic TL-01 phototherapy
2. Anti-oxidants
3. Avoid iron
180
What is the enzyme affected for acute intermittent porphyria?
PB deaminase
181
What are the five virulence factors?
1. Adhesin
2. Invasin
3. Impedin
4. Aggressin
5. Modulin
182
What is the virulence factor that enables binding of the organism to host tissue?
Adhesin
183
What is the virulence factor that enables the organism to invade a host cell?
Invasin
184
What is the virulence factor that enables the organism to avoid host defence mechanisms?
Impedin
185
What is the virulence factor that causes damage to the host directly?
Aggressin
186
What is the virulence factor that induces damage to the host indirectly?
Modulin
187
What are the most important adhesins in Staph aureus?
Fibrinogen-binding
| Collagen binding
188
Name a toxin in Staph aureus that has specific toxicity for leukocytes?
Panton-Valentine Leukocidin
189
What two severe skin infections is PVL associated with?
Recurrent furunculosis
| Necrotising fascilitis
190
What - linked with PVL and alpha toxin is responsible for necrotising pneumonia and contagious severe skin infections?
CA-MRSA
191
What are the four diagnostic criteria for necrotising pneumonia?
1. Fever - 39
2. Diffuse macular rash and desquamation
3. Hypotension
4. > 3 organ systems involved
192
Name three skin infections caused by Streptococcus pyogenes?
1. Impetigo
2. Cellulitis
3. Necrotising fascilitis
193
Name a way Strep pyogenes adheres?
Hyaluronic acid capsule
194
Is impetigo contagious?
Yes
195
Name an important S.pyogenes disease that involves pyrogenic exotoxins?
Toxic shock like syndrome
