Week 1 Flashcards
1
Q
The layers of skin
A
Epidermis
Glands / hairs/ nails
Dermis
Sub cutis
2
Q
What is the layer between epidermis and dermis called
A
Dermo-epidermal junction
3
Q
Function of dermo-epidermal junction
A
Semi permeable membrane filtering substances that crosses
Anchors the epidermis to the dermis
4
Q
The dermis is mainly
A
Connective tissue
5
Q
The Sub cutis layer is mainly
A
Fat
6
Q
The layers of epidermis (from top to low)
A
Keratin layer
Granular layer
Prickle cell layer
Basal layer
7
Q
What are basal stem cells
A
Cells that can differentiate into a specific type of cell of the epidermis and migrate through it to replace it
8
Q
Where are basal stem cells located at
A
Basal layer of epidermis
9
Q
What cells are in the epidermis
A
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
Basal cells
10
Q
Which type of cells make up the most of epidermis
A
Keratinocytes
11
Q
Function of langerhans cells
A
Dendritic cells involved in immunological functions of the skin
12
Q
Function of Merkel cells
A
Mechanoreceptor cells
13
Q
Function of melanocytes
A
Pigment producing dendritic cells protecting against sun damage
14
Q
Where are langerhan cells located at
A
Prickle cell layer of epidermis
15
Q
Where are Merkel cells located at
A
Basal layer of epidermis
16
Q
Where are melanocytes located at
A
Basal layer of epidermis
17
Q
Basal cells at the basal layer are which type of cells
A
Cuboidal cells
18
Q
Features of structure of prickle cell layer
A
Large polyhedral cells
with a lot of desmosomes in between the cells acting as connections
19
Q
Features of granular layer
A
2-3 layers of flatter cells
Cells do not have nuclei
Lamellar bodies
20
Q
Features of keratin layer
A
Mostly corneocytes (dead keratinocytes)
Lamellar granules
Waterproof barrier
21
Q
Function of keratin layer
A
Prevents entry of unwanted substaces
Prevents excessive loss of water
22
Q
The cells at the outermost layer of epidermis are
A
Dead cells (corneocytes) which are continually shed and replaced from below
23
Q
What makes the keratin layer waterproof
A
Cells are close to each other
Lamellar granules release lipids which is hydrophobic
24
Q
How do melanocytes protect us against sun damage
A
- Melanocytes produce melanin
- Melanin absorb light and are contained in melanosomes
- Melanosomes are then transported to adjacent keratinocytes by dendrites of the melanocytes
- This induces pigmentation and protect the basal cells against UV radiation by absorbing the UV light (because it is black)
25
What causes different skin colours
1. Due to different activity level of melanocytes.
- e.g. melanocytes in black skin has higher activity level = produce more melanin = more pigmentation
2. Ratio between eumelanin and phenomelanin
26
What is vitiligo and what causes it
Vitiligo = patches of skin losing colour
Due to autoimmune destruction attacking melanocytes
27
What causes albinism
Genetic disorder reducing melanin production
28
What causes skin hyperpigmentation in Addison's disease
High ACTH stimulating melanocytes to produce more melanin
29
Structure of hair follicles
Specialized keratins
Hair papilla is in the dermis layer and it extends into the epidermal layer and out of the skin
Sebaceous gland next to it
Arrector pili muscle attached to the hair follicles
30
Function of arrestor pili muscle
It contracts to erect the hair when you're cold to provide thermal insulation
= causes goosebumps
31
What condition affects the arrestor pili muscle
Leprosy
32
What causes hair to be pigmented
Melanocytes in epidermis
33
What are the phases of growth of hair
Anagen
Catagen
Telogen
34
What is anagen
Growth of new hair
35
What is catagen
end of active hair growth and cuts individual hairs off from the blood supply and from the cells that produce new hair (forms club hair)
36
What is telogen
resting period when strands remain in their follicles till they shed
37
Most hair at any time are in which phase
Anagen
38
Why can animals' fur shed at the same time whereas human hair does not
Because animals have synchronous telogen phase whereas in humans the telogen phase of each hair is different
39
List the outer structures of the nail
Nail plate
Nail folds
Eponychium
40
What are the nail folds
The skin around the nail that protects the margin of the nails
41
What is the eponychium
keratin layer of the skin that extends over the proximal nail plate
42
What are the structures underneath the nail plate
Nail bed
Germinal matrix
Hyponychium
43
What is the nail bed
Directly underneath the nail plate providing a smooth surface for the nail plate to glide over during growth
44
How do nail plates grow
Cells in germinal matrix divide and become keratinised. The continuous cell division pushes the nail plate, letting it glide over the nail bed = nail becomes longer
45
What is the hyponychium
The area underneath the free edge of nail plate
46
What are the 2 layers of dermis
Papillary dermis
Reticular dermis
47
Describe the papillary dermis and reticular dermis layers
Papillary dermis is thinner and it is just below the epidermis
Reticular dermis layer is thicker and contains several structures
48
What structures are in reticular dermis layer
Blood vessels
Pilosebaceous units (sebaceous gland + hair follicle)
Lymphatics
Nerves
49
Structures in dermis
Blood vessels
Lymphatics
Nerves
Collagen and elastin fibres
Hair follicles
Glands
Cells
50
What cells are present in dermis
Macrophage
Mast cells
Langerhans cells
Fibroblasts
51
What are the 2 types of aging
Intrinsic and extrinsic
52
What is intrinsic aging
Inevitable physiological process that causes skin to look more saggy and less firm, hollowed cheeks as you age
53
What is extrinsic aging
Skin aging due to external factors such as UV light, smoke particles, pollutants on top of intrinsic aging
54
If an area of skin aging is mostly due to extrinsic aging, what would the features be
Coarse wrinkles (deep wrinkles)
Loss of elasticity
Rough texture appearance
Hypertrophic photoaging
55
If an area of skin aging is mostly due to intrinsic aging, what would the features be
Fine wrinkles
Dry skin
Thin skin
Telangiectasia
Atrophic photoaging
56
Atrophic photoaging increases the risk of
Non melanoma skin cancer
57
What type of plexus do vessels in dermis form
horizontal plexuses
58
Dilation of lymphatic vessels in the dermis can cause
Chronic lymphoedema
59
Dilation of blood vessels in the dermis can cause
Angioma
60
What structures are responsible for the innervation of the skin
Free sensory nerve endings
Special receptors
Motor nerve fibre
61
What are the special receptors for sensory innervation of the skin
Pacinian corpuscle
Meissners corpuscle
62
Pacinian corpuscle is for what type of sensory
Pressure
63
Meissner corpuscle is for what type of sensory
Vibration
64
Where is Meissener's corpuscle located at
Papillary layer of the dermis
65
Where is Pacinian corpuscle located at
Reticular layer of dermis
66
What is alopecia areata and what causes it
Patchy hair loss
Due to autoimmune destruction of hair papilla causing hair to fall out
67
Does hair grow back in affected areas in alopecia
Yes, because the stem cells are not attacked
68
What are the 3 types of glands present in skin
Apocrine
Eccrine
Sebaceous
69
What is eccrine gland
Sweat glands that open directly onto the skin surface
70
What is apocrine gland
glands that drain into hair follicles
71
What are sebaceous glands
Glands in hair follicles that secrete sebum
72
When do sebaceous glands become active and start producing sebum
During puberty
73
What happens when sebaceous glands are clogged because they produce too much sebum
Acne
74
Function of sebum
Control moisture loss from skin
Protects against infection
75
On which body parts are sebaceous glands found
Everywhere except Soles and palms
76
On which body parts are eccrine glands found
Everywhere ESPECIALLY palms, soles, forehead and axillae
77
Function of eccrine gland
Thermal regulation
Aid grip
78
On which body partsare apocrine glands found
Axillae
Groin
Eyelids
Ears
Perineal region
79
Functions of the skin
Barrier
Metabolism and Detoxification
Thermoregulation
Immune defense
Sensation
80
What is metabolised by the skin
Thyroid hormones
Vitamin D
81
What does the skin do to thyroid hormones
Converts T4 into metabolically active T3
82
Around how much % of thyroid hormones are metabolised (converted) by the skin
80%
83
Role of Vitamin D
To increase serum Ca2+ when there is a decrease.
By increasing absorption of Ca2+ from digested food in intestines and reabsorption of Ca2+ in kidneys
84
2 forms of Vitamin D
Vitamin D2
Vitamin D3
85
Which form of Vitamin D is more effective in raising serum vitamin D (metabolically active form)
Vitamin D3
86
Vitamin D2 is obtained by
Ingestion of plants esp mushroom
87
Vitamin D3 is obtained by
Mostly made by the skin
ingestion
88
How does the skin synthesise vitamin D3
By the action of ultraviolet B from sunlight on 7-dehydrocholesterol
89
What happens to vitamin D3 after it is synthesised in the skin
Stored in the liver then it is converted into its biologically active form in the kidneys
90
Causes of vitamin D deficiency
Lack of sunlight
Lack of vitamin D in diet
Malabsorption
Kidney disorders
91
Vitamin D deficiency can cause
Osteomalacia
Rickets in children
Secondary hyperparathyroidism
92
What is rickets
A condition that affects the development of bones in children causing bone pain, poor growth and weak bones that can lead to bone deformities
93
What can be caused if there is damage to skin barrier
Fluid loss
Protein loss -> hypoalbuminaemia
Infection
94
What factors that contribute to skin act as an immunological defence against pathogens
Keratin layer
Keratinocytes
Immune cells of the epidermis and dermis
95
How do keratinocytes provide immunological defence against pathogens
When they sense pathogens using cell surface receptors:
Produce anti-microbial peptides (AMP)
Produce cytokines and chemokine
96
What are the immune cells in the epidermis
Langerhan cells
T cells
97
What are the immune cells in the dermis
T cells
Dermal dendritic cell
Plasmacytoid dendritic cell
Macrophages
Neutrophils
Mast cells
98
What is a characteristic feature of Langerhan cells
Birbeck granules
99
Which type of T cell is the main T cell found in dermis layer
CD8+
100
Which types of T cells are found in the epidermis layer
CD4+ and CD8+
101
What are CD8+ cells
Differentiate into cytotoxic cells
102
What are CD4+ cells
Helper cells that differentiate into different helper cells to produce different cytokines
They also instruct CD8+ cells and B cells
103
What are the different Helper T cells differentiated from CD4+
Th1
Th2
Th17
104
Th1 function
Secrete IL2 and IFNy to activate macrophages
105
Th2 function
Secrete IL4 IL5 IL13 to stimulate B cells
106
Th17 function
Secrete IL17 to modulate immunity
107
Function of the dendritic cells in the dermis
To present antigens to T and B cells
108
Which immune cell is responsible for allergy
Mast cells
109
What type of disorder is psoriasis classified as
Autoimmune disorder
110
Pathogenesis of psoriasis
1. Keratinocytes under stress release AMP and cytokines that stimulate plasmacytoid dendritic cells in dermis to produce other cytokines
2. these chemical signals causes dendritic cells to present to T cells
3. Th1 and Th17 predominant
4. Causing inflammation cascade
5. Causes keratinocyte proliferation and increased epidermal turnover
111
What are the 5 types of psoriasis
Chronic plaque psoriasis
Inverse psoriasis
Guttate psoriasis
Pustular psoriasis
Generalised psoriasis
112
Which immune complex is mainly present in psoriasis
Th1
Th17
113
Which type of psoriasis is the most common
Chronic plaque psoriasis
114
What are the clinical features presented in chronic plaque psoriasis
Plaques that are :
Symmetrical
Scaly
Well demarcated
itchy
115
Where are chronic plaque psoriasis usually found
Extensor surface distribution
Scalp
Lower back
116
Where are the extensor surfaces
Front of the knee
Back of the elbow
117
What are the clinical features caused by inverse psoriasis
Smooth erythematous plaques
118
Where is inverse psoriasis usually found
Areas where the skin rubs against each other
- axilla
- groin
- gluteal cleft
- genital area
119
What clinical features are caused by guttate psoriasis
Sudden emergence of multiple small tear drop shaped erythematous plaques
120
Guttate psoriasis usually occurs after
Streptococcal infection e.g. Strep throat
121
What may be a common illness patients with Guttate psoriasis have a week before rashes appear
Tonsilitis
122
What clinical features are presented in pustular psoriasis
Multiple red round spots (petechiae)
Multiple pustules
123
Where are pustular psoriasis commonly found and what is the other name for pustular psoriasis
On palms and soles
Hence it is also called palmoplantar pustulosis
124
What are the subtypes of generalised psoriasis
Erythrodermic psoriasis
Generalised pustular psoriasis
125
Risk factors for developing psoriasis
Genetics
Obesity
Smoking
HIV
126
Risk factors that can exacerbate psoriasis
Skin trauma (Koebner Phenomenon)
Streptococcal infection
Stress
Drugs
Withdrawal of steroids
Hormones
127
What is Koebner's phenomenon
Skin trauma leads to new lesions occurring at sites of skin trauma meaning it triggers psoriasis in an area that was not previously affected
128
Koebner's phenomenon can be seen in which other conditions except from psoriasis
Vitiligo
Lichen Planus
129
What drugs can exacerbate psoriasis (BALI)
Beta blockers
ACEi
Antimalarials (hydroxychloroquine)
Lithium
Indomethacin (NSAID)
130
Psoriasis is associated with which other conditions
Psoriatic arthritis
IBD
higher risk of developing other autoimmune diseases
131
Apart from the skin, what other signs of psoriasis can be see
Nail involvement
- nail pitting
- nail onycholysis
- thickening of nail bed
132
Why should patients with psoriasis avoid scratching
Because it can lead to skin trauma -> Koebner's phenomenon -> psoriasis flare up
133
What is a sign of psoriasis
Auspitz sign
134
What is Auspitz sing
Removal of surface scale reveals tiny bleeding points
135
What will a biopsy of psoriatic skin show
Thickened epidermis
Parakeratosis: Retention of nuclei of corneocytes at keratin layer (they should not have nuclei because they are dead cells)
Inflammatory cells
136
What is parakeratosis
Retention of nuclei of corneocytes at keratin layer due to abnormal differentiation and proliferation of keratinocytes
137
Management of chronic plaque psoriasis
1. Topical therapy
2. Phototherapy
3. Systemic therapy
138
Describe the topical therapy for psoriasis
Emollients with
1. Topical steroid + Topical vitamin D
2. Stop topical steroid but continue topical vitamin D twice daily
3. Stop topical vitamin D but continue topical steroid twice daily
139
Examples of topical vitamin D
Calcipotriol
Calcitriol
140
Why do you need to stop using topical steroid after certain amount of time
To avoid side effects such as unstable psoriasis / striae
141
How long can you use a potent topical steroid for
4 weeks
142
Mildly potent topical steroids are used in psoriasis for areas such as
Face
Groin
Breasts
143
What are the drugs commonly used for topical steroid + topical via D therapy for psoriasis
Betamethasone (steroid) + calcipotriol
144
What are the alternatives topical treatments for psoriasis if topical steroids + vitamin D are ineffective / contraindicated
Tar
Dithranol
145
When is phototherapy indicated for psoriasis
If
- extensive psoriasis
- nail disease which cannot be treated topically
- ineffective topical therapy
146
What types of phototherapies are there for psoriasis
UVB
PUVA (psoralen + UVA)
147
When is PUVA used and why shouldn't it be used unless necessary
PUVA used if UVB is ineffective
PUVA is not used unless necessary due to its side effects: increase risk in skin cancer, skin irritation
148
PUVA + usage of which drug can increase risk of skin cancer
Ciclosporin (medication used in systemic therapy for psoriasis)
149
PUVA should be avoided in which group of people
- those that are using / likely to use ciclosporin
- young
- light skin type (they are already prone to skin cancer)
150
When is systemic therapy indicated in psoriasis
If psoriasis is not controlled by topical therapy
+ significant impact on wellbeing
+ extensive psoriasis / nail disease / ineffective phototherapy
151
Describe the order of drugs used in systemic therapy for psoriasis
1. Methotrexate
2. Ciclosporin
3. Acitretin
152
Contraindications for methotrexate
Those that are pregnant / planning to be pregnant
153
Advise given to patients who are going to use methotrexate
Contraception during treatment and 6 months after ending treatment
154
When is ciclosporin used in psoriasis
For patients considering pregnancy
For rapid disease control
For patients with palmoplantar pustulosis
155
What does atopy mean
When a patient has predisposition to abnormally exaggerated IgE response to allergen
156
Atopic individuals are at risk of developing which conditions
Atopic dermatitis
Asthma
Allergic rhinitis
Food allergy
157
Atopic dermatitis is most common in
Children, most present symptoms by the age of 5
158
Causes of atopic dermatitis
Multifactorial - genetics, environment, immunological
159
What genetic factor contributes to causing atopic dermatitis
Mutation in FLG gene which codes for filaggrin protein. Filaggrin protein is required for effective skin barrier hence mutation in FLG gene -> ineffective skin barrier
160
How does ineffective skin barrier contribute to atopic dermatitis
Ineffective skin barrier allows antigens to enter the skin more easily which causes sensitization of the allergen then trigger inflammation in allergen stage
161
Which immune complexes are mainly present in atopic dermatitis
Th2
Mast cells
162
Patients with atopic dermatitis are more likely to have
Food allergy
Allergic rhinitis
Asthma
163
What can trigger flares of atopic dermatitis
Certain chemicals in soaps / detergents / shampoo / perfume
Stress
Food
Fabrics
Hormones
Dry weather
164
Symptoms of atopic dermatitis
Pruritus
Erythema
Scaling
Dry skin
Nodular pruigo
Flexural distribution of symptoms in older children / adults
165
What is the distribution of atopic dermatitis in infants
Extensor surfaces
Face - cheeks
Neck
Scalp
Eyelids
166
What are nodular pruigo
Very itchy nodules most commonly present in black people with atopic dermatitis
167
What can you see in skin biopsy of atopic eczema
Spongiosis - intraepidermal oedema
168
Diagnostic criteria for atopic dermatitis
Pruritus + 3 or more of the following:
- flexural dermatitis (or extensor dermatitis in infants)
- PMH of flexural dermatitis
- PMH of asthma / allergic rhinitis
- Dry skin in the last 12 months
169
What is the first line treatment for atopic dermatitis
Identify and avoid triggers
170
Management for mild atopic dermatitis
Emollients
Mild potency topical steroids (hydrocortisone)
171
Management for moderate atopic dermatitis
Emollients
Moderate potency topical steroids
Topical calcineurin
Bandages
172
Management for severe atopic dermatitis
Emollients
Potent topical steroids
Topical Calcineurin
Phototherapy
Systemic therapy
173
What drugs are used in the systemic therapy for atopic dermatitis
Methotrexate
Azathioprine
Prednisolone
174
Which drugs that are used in systemic therapy for atopic dermatitis are not safe in pregnancy
Methotrexate
Azathioprine
175
Complications of atopic dermatitis
Infection due to ineffective skin barrier
Mental health
176
What infections are at increased risk due to atopic dermatitis
S aureus
Eczema herpeticum
177
What symptoms does S aureus infection cause in a patient with eczema
Oozing rash (weeping eczema) fluid seeping onto skin surface due to blood vessel dilatation causing fluid to leak out
Oedema
178
Eczema herpeticum is caused by
Herpes simplex virus
179
Treatment of eczema herpeticum
IV aciclovir
180
What does acanthosis mean
Increased thickness of epithelium
181
What does parakeratosis mean and in which condition is it present
Persistence of nuclei in the keratin layer
Present in psoriasis
182
What does hyperkeratosis mean
Increased thickness of keratin layer
