Dermatology Flashcards
What are the functions of the skin?
Barrier against environmental insults Temperature regulation Sensation Vitamin D synthesis Immunosurveillance
What is erythroderma?
Intensereddening of the skin due toinflammatoryskin disease, affecting >90% of surface area. It is erythematous and exfoliative.
What are the complications of erythroderma?
Hypothermia (thermoregulation lost)
Infection (barrier lost)
Renal failure (insensible losses)
High output cardiac failure (dilated skin vessels)
Protein malnutrition (high skin cell turnover)
What are the signs of erythroderma?
Skin is erythematous, thickened, inflamed, and scaly, with no sparing
What are the symptoms of erythroderma?
Pruritis, fatigue, anorexia, feeling cold.
What are the causes of erythroderma?
Pruritis, eczema, drugs, cutaneous T cell lymphoma
What are the four major cell types of the epidermis?
Keratinocytes
Langerhan cells
Melanocytes
Merkel cells
What is the function of keratinocytes?
To form a protective barrier
What is the function of Langerhan cells?
Antigen presenting cells
What is the purpose of melanocytes?
Produce melanin, which pigments the skin and protects cell nuclei from UV DNA damage
What is the function of Merkel cells?
Contain specialised nerve endings, for sensation.
What are the layers of the epidermis?
Stratum basale (basal layer)
Stratum spinosum
Stratum granulosum
(Stratum lucidum in areas of thicker skin (palm, sole))
Stratum corneum (horny layer, superficial)
What does each layer of the epidermis represent?
A different stage of keratinocyte maturation
Total turnover time ~30 days
What is the dermis composed of?
Collagen, elastin, glycosaminoglycans (strength, elasticity)
Immune cells, nerve cells, skin appendages, lymphatics, blood vessels
What are sebaceous glands?
Glands producing sebum through hair follicles (pilosebaceous unit) onto the skin.
They become active after puberty, stimulated by the conversion of androgen to dihydrotestosterone.
When is sebum production increased?
With associated bacterial colonisation, in conditions such as acne vulgaris.
What are the functions of eccrine and apocrine glands?
Regulate bodily temperature
Where are eccrine and apocrine glands found?
Eccrine are widespread
Apocrine are active following puberty, and are found in axillae, areolae, genitalia, and anus
How are eccrine and apocrine glands innervated?
By the sympathetic nervous system
What are the three main types of hair?
Lanugo hair (downy hair on foetus/newborn) Vellum hair (short bodily hair) Terminal hair (coarse long hair)
What are the three growth phases of a hair follicle?
Anagen (active growth, rapid hair root division and shaft elongation)
Catagen (resting stage)
Telogen (regression stage)
What are nails comprised of?
A nail plate arising from the nail matrix at the posterior nail fold. It rests on the nail bed, which contains blood capillaries.
