Skin Flashcards
Alopecia Areata
autoimmune hair loss
- psychosocial impact if effects scalp - especially in women
UV induced abnormalities
- sunburn doesn’t occur in black skin
- skin ageing in whites (photoageing)
skin cancer in whites - basal cell carcinoma
- malignant melanoma
Epidermis
- stratum corneum - (horny layer - barrier - made up of layers of flattened corneocytes)
- granular layer (keratinocytes differentiate into corneocytes)
- prickle cell layer (joined by desmosomes)
- basal layer (keratinocytes mitosis occurs here mainly)
Melanocytes
- occurs at intervals along the basal layer of the epidermis
- dendritic - professional antigen presenting cell
- produce melanin - main pigment that gives skin its colour - produces more melanin but the actual cells are not increased in number in black or tanned skin
Melanosomes lie on the sunny side of nucleus to protect it from UV light
Langerhans cells
- dendritic cells of bone marrow origin
- scattered through the prickle cell layer
- highly specialised capacity to present antigens to T lymphocytes
- mediate immune reactions e.g. Allergic contact dermatitis
Psoriasis
- abnormal epidermal growth and differentiation
- in 2% of the population
Extreme proliferation of the epidermal basal layer, causing gross thickening of the prickle cell layer and production of excessive stratum corneum cells (manifesting clinically as excessive scaling) - loss of fluid, protein, other nutrients, heat
- excessive absorption of potentially harmful exogenous agents especially drugs
Allergic contact dermatitis
- Langerhans cells and T lymphocytes
Malignant melanoma
- an aggressive malignant tumour (neoplasm) of melanocytes
- retention of tumour cells above the epidermal basement membrane is associated with a good prognosis
Vitiligo
autoimmune depigmentation
- psychosocial impact if affects visible areas in dark-skinned raves
- much less noticeable in whites
- immune system attacks melanocytes - usually in symmetrical localised areas of skin
Acne
a skin disease affecting sebaceous glands
- sebaceous gland ducts become obstructed
- increased sebum production
- infection with normally harmless skin bacteria
Hyperhidrosis
increased sweating
- may affect only the palms and soles
- embarrassing wet hands - substantial problem
Barrier function of skin
Stratum Corneum - major barrier preventing percutaneous absorption of exogenous substances
- can be seriously disrupted by many diseases
Sensation problems
Due to leprosy and diabetic sensory neuropathy
- minor injuries not noticed - injection leads to loss of tissue
Thermoregulation
Vascular thermoregulation
- dilation of skin blood vessels
- constriction of skin blood vessels lead to pallor and heat conservation
(failure can lead to hypothermia)
Thermoregulatory eccrine sweating
- evaporation of eccrine sweat causes cooling
IMPORTANCE IN THE MAINTENANCE OF BODY TEMPERATURE
