Introduction to General Dermatology Flashcards
What are the three layers of the skin? (inner to outer)
- Hypodermis (subcutaneous tissue)
- Dermis
- Epidermis (composed of 5 distinct layers)
Describe the composition of the dermis
- Collagen and elastin matrix with mucopolysaccharide gel
- Fibroblasts, dermal dendritis cells and macrophages
Describe the function of melanocytes
- Synthesize melanosomes (collections of melanin)
- Melanosomes get excreted and phagocytosed into keratinocytes, where they sit above the nucleus
Describe the function of Langerhans cells
Process antigens and migrate to lymph nodes to induce an immune response
What are the 5 layers of the epidermis? (inner to outer)
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
Mnemonic for layers of the epidermis?
- Come (corneum)
- Lets (lucidum)
- Get (granulosum)
- Some (spinosum)
- BOOZE (basale)
Brief description of function / makeup of each layer of epidermis?
- Basale: least differentiated, divides to regenerate superficial layers
- Spinosum: Keratinocytes and Langerhans cells accumulate
- Granulosum: keratohyalin and a hard protein envelope, Lamellar bodies release lipids, cells die
- Lucidum: Dead cells with dispersed keratohyalin (only in palms and soles, acc to kenhub)
- Corneum: Dead keratin containing cells, also lipids and hard protein envelope
What are the three phases of the hair cycle? Brief description of each
- Anagen: growing phase, 80-90% of hair
- Catagen: Growth stops, follicles shrink. Lasts 2-3 weeks, 1-3% of hairs
- Telogen: Resting phase, 1-4 months, up to 10% hair
What are the main functions of the skin?
- Thermoregulation: insulation / heat transfer
- Immunity
- Barrier / protection (protects against chemicals / organisms and keeps water / electrolytes in)
- Sensation (temp. touch. pain)
- Vitamin D synthesis
- “interpersonal communication” (appearance / smell)
Describe the step in vitamin D synthesis that occurs in the skin
- UV light converts 7-dehydrocholesterol to cholecalciferol
- Cholecalciferol = vitamin D3
What are some external causes of skin disease?
- Temperature (hot or cold)
- UV light exposure
- Chemicals
- Infection
- Trauma
What are some internal causes of skin disease?
- Systemic disease
- Genetics
- Drugs
- Infection
What is a common cause of photosensitivity? How is the disease distributed over the body? What types of light are patients vulnerable to?
- Medications / pharmaceuticals
- Areas exposed to light are affected
- Can be sensitive to UVA, UVB, visible light, or a combination of these
What is Bullous Pemphigoid?
- An autoimmune skin disease mostly in elderly people
- Involves the formation of blisters (bullae) in the space between the epidermal and dermal skin layers
Define macule and patch in regards to the description of skin lesions
- Macule Small circumscribed area
- Patch Larger circumscribed area
Define papule and plaque in regards to the description of skin lesions
- Papule Small raised area
- Plaque Larger Raised area
Define vesicle and bulla in regards to the description of skin lesions
Vesicle Small Fluid filled area
Bulla Large Fluid filled area
Define pustule and abscess in regards to the description of skin lesions
Pustule Small Pus filled area
Abscess Large Pus filled area
Define erosion and ulcers in regards to the description of skin lesions
Erosion Loss of Epidermis
Ulcer Loss of Epidermis and dermis
What is Erythema?
- Redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries.
- Occurs with skin injury, infection, or inflammation.
What factors are important in describing the distribution of a dermatosis?
- Isolated (solitary) or multiple
- Localized or diffuse
- Symmetrical?
What can Eruptive xanthoma be a sign of? How does it appear?
Hyperlipidaemia
- Appears as multiple fatty papule’s on the skin surface
What can Acanthosis Nigricans be a sign of? How does it appear?
- Can be a sign of insulin resistance, obesity, malignancy
- Appears as hyperkeratosis and Hyperpigmentation, papules with a ‘velvety’ appearance
What can Pretibial myxoedema be a sign of? How does it appear?
Thyroid disease, occurs in 5% of Graves
- Appears as multiple rough, red plaques on the feet & ankle
