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65 Cards in this Set
- Front
- Back
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Functions of the skin |
Protection from damage Barrier (water and bacteria) Sensation Metabolic (Vit D3) |
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Three layers of skin? |
Epidermis Dermis Subcutis |
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What is the structure of the Epidermis? |
Stratified Squamous Epithelium |
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What is the structure of the dermis? |
Dense, irregular connective tissue: fibroblasts, Collagen I, elastin, blood, nerves and receptors. Divided into papillary and reticular dermis |
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What does the subcutis layer contain? |
Adipose tissue and blood vessels. |
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What layers or strata are found in the epidermis? |
Keratinocyte layers |
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(From top to bottom)
C L G S B |
Corneum Lucidum Granulosum Spinosum Basale |
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Barriers in the keratinocytes layers? |
Tight junctions Desmosomes and hemidesmosomes Keratin Phospholipid |
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Name 4 skin cell types found in the epidermis? |
Keratinocytes Melanocytes Langerhans cells Merkel cells |
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What are Keratinocytes? |
Stratified squamous keratinising epithelial cells Produce keratin |
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What are melanocytes? |
Pigment synthesising cell Melanosomes in cytoplasm contain melanin and are passed to keratinocytes - scattering of UV light. |
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What are Langerhans cells? |
Bone marrow derived. Dendritic, antigen presenting cells. |
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What are Merkel cells? |
Clear cells in SB. Plentiful in touch areas. Connected to keratinocytes and Afferent nerves. Neuroendocrine function |
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The epidermis: composition, function,disorder and pathology. |
Composed mainly of IV collagen, glycoproteins (laminin secreted by epithelial cells. Fibronectin from fibroblasts) and GAGs Function - adhesion, barrier, organisation of skin Disorders- renal disease, cancer, genetic disease Skin pathology - junctional epidermolysis bullosa, bullous pemphigold - separation of dermis and epidermis |
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How are Blistering Disorders classified? |
Classified according to the epidermal layer where the separation occurs. |
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How are blistering disorders caused? |
Are caused by auto-antibodies to constituents of epithelium or basement membrane. |
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What occurs in Pemphigus? |
IgG auto-antibodies to components of desmosomes: acantholysis |
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What occurs in Bullous pemphigoid? |
Deposition of IgG auto-antibodies to BM proteins |
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What occurs in Dermatitis herpetiformis? |
Deposition of IgA auto-antibodies to fibrils that bind BM to dermis, associated with coeliac disease. |
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What is epidermolysis bullosa? |
Group of rare inherited conditions causing separation of the epidermis from the dermis with minimal shearing forces, no inflammatory cell infiltrate. |
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Name three different types of EB |
EB simplex: Defective cytoskeleton Junctional EB: Defective hemidesmosomes Dystrophic EB: Defective BM collagen |
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What is the makeup of Dermis? |
Dense connective tissue: Collagen 70% -Papillary: conical papillae, richly vascularised, lymph and nerve. -Reticular: Horizontal collagen and elastin fibres -Contains hair and gland structures |
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What are the two different types of skin innervation |
Afferent nerve endings Efferent nerve endings |
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What are the different types of afferent nerve endings? |
Pacinian corpuscle Meissners corpuscle Ruffini corpuscle Free nerve endings |
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What do Pacinian corpuscles react to? |
Deep pressure Vibration (Found in subcutis) |
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What do the Meissners corpuscle react to? |
Light touch sensation (In papillary dermis) |
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What do the Ruffini corpuscle react to? |
Mechanoreceptors (dermis of feet) |
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What do free nerve endings detect? |
Pain, itch, temp Found in papillary dermis. |
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What do the efferent nerve endings detect? |
Vessel diameter and blood flow Information to sweat glands and erector pili muscles |
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Skin specialisations |
Hair follicles Sweat glands Sebaceous glands |
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Examples of systemic disease with skin involvement |
SLE - Butterfly rash, vasculitis AIDS - Kaposi Sarcoma RA - Vasculitis |
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Dermatitis overview |
Involves dermis and epidermis Acute - Urticaria Chronic - Psoriasis, Lichen planus Non specific - Eczema |
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What is Eczema? |
Group of diseases, giving red, itchy skin with tiny blisters. Scaly, crackling, bleeding. |
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What is the mechanism of eczema? |
Failure of the skin barrier causing loss of water and the influx of allergens. |
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What can the distribution suggest? |
The cause |
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Swelling in the epidermis is called |
Spongiosis |
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What can pronged rubbing or scratching of affected skin cause? |
Thickened skin, hyperkeratosis and acanthosis. |
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Chronic inflammation in the dermis can cause |
Oedema and fibrosis. |
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What is the difference between Psoriasis and eczema? |
The type of inflammatory cell involved, neutrophilic in Psoriasis. |
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Psoriasis gross appearance |
Red raised plaques covered by thick white scale that bleeds on removal. |
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Changes to epidermis in Psoriasis |
Rapid rate of epidermal cell renewal. Thin with parakeratosis: scales. |
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Changes to Dermis in Psoriasis |
Oedema and numerous capillaries |
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Infection of the skin: Overview of types |
Bacterial: Superficial/Deep Viral: Herpes, HPV Fungal: Ringworm, athletes foot Myobacteria: TB, Leprosy Protozoa: Leishmania Parasites: Scabies |
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Bacterial: Impetigo |
Staph/Strep Infection - Subcorneal bullae +/- neutrophils - Burst and spread: yellow crusting - Highly contagious, children |
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Bacterial: Cellulitis |
Strep pyrogenes/staph - Superficial dermis, spreading factor - Can lead to necrotising fasciitis Limbs - penetration injury/bite |
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Bacteria - Boil |
Infection in a hair follicle |
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Bacteria: Acne |
Infected follicle blocked with a keratin plug |
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What are the three types of skin cancer? |
Basal cell carcinoma Squamous cell carcinoma Melanoma |
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Basal cell carcinoma overview |
Most common 75-80% Rare in dark skin Linked to sun exposure Common on head, neck, chest, back, forearm and hands Non-metastasising cancer of basal cells Diagnosed by biopsy, removed and monitored. Curable |
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Basal cell carcinoma appearance |
Smooth translucent nodule (flesh/pink) with telangiectatic vessels under surface Can be flat, scaly erythematous plaque with vessels and modular borders Extends wide and deep, central depression and ulceration |
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Squamous cell carcinoma overview |
10-20% Linked to sun exposure and occupational exposure (arsenic/coal) Men x2 prevalence Malignancy of upper epidermal layers Intraepidermal or invasive Invasion can be from intraepidermal or other pre-malignant lesions Curable, diagnosed by biopsy, remove and monitor. 5year survival with metastases - 25% |
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Squamous cell carcinoma gross appearance |
Red, scaly, slightly elevated with irregular border. Ulcerates with raised red border and crusts Common on nose, forehead, ear, lip and hand. |
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Dysplasia overview |
Disordered growth, usually epithelial. Does not necessarily lead to cancer. If stimulus removed, tissue may become normal. |
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Skin pigmentation overview |
Varied skin colour is due to increased melanocytes activity. |
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Disordered pigmentation examples: |
Lentigo maligna Albinism: Lack of melanin due to lack of enzyme required to make melanin - tyrosinase Vitiligo: Macules of de pigmented skin enlarging over time. |
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What are Nevi? |
Congenital/acquired benign tumours |
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Nevi can be |
Pigmented/non, hairy/not, flat/elevated. |
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Nevi are more abundant on |
Sun exposed skin |
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Name 4 types of Nevi |
Nevocellular Nevi Junctional Nevi Compound Nevi Dermal Nevi |
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What are Dysplastic Nevi? |
Atypical groups of melanocytes at epidermal-dermal junction: pleiomorphism, mitoses.
Irregular border, pigmentation and surface Often >5mm Occur on exposed and unexposed skin. |
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Melanoma overview |
Rapidly progressing/metastatic Arise from pre-existing or new Nevi Uneven surface, irregular borders, slightly raised, black/brown colour Most common on areas exposed intermittently |
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3 types of Melanoma |
Lentigo malignant melanoma Superficial spreading Nodular |
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Melanoma staging |
Breslow thickness - Histological distance from deepest melanoma cell to SG of epidermis. Risk of metastasis: low. |
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Melanoma risk factors |
Excessive exposure to UV Risk in fair skinned Increase with FH History of 3 or more blistering sunburns under 20 Precious PUVA therapy, immunosuppressive or dysplastic Nevi |
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Melanoma ABCD |
Asymmetry Border (irregular) Colour Diameter |
