Skin Flashcards
Describe the macroscopic features of skin
Colour Hair Thickness Laxity Oiliness
Describe what factors cause variation in the macroscopic appearance of skin
Age Sex Ethnicity Exogenous influences e.g. UV exposure Site e.g. lips
Give 3 conditions where variations in skin change the epidemiology of the disease.
Vitiligo: more psychosocial impact in dark skinned races, less noticiable in whites
Alopecia Areata: greater psychoscial impact in women especially on scalp
UV induced abnormalities e.g. basal cell carcinoma and malignant melanoma more likely in whites along with skin ageing. Sunburn does not occur in black skin
State the 4 regions of the epidermis in decending depth
stratum corneum
granular layer
prickle cell layer
basal layer
Describe keratinocyte differentiation
Keratinocyte mitosis occurs in the basal layer
Daughter keratinocytes move into the prickle cell layer where terminal differentiation begins. (cells lose ability to divide)
In granular layer, cells lose plasma membrane and begin differentiating into corneocytes
The stratum corneum consists of flattened corneocytes
Describe melanocytes and where they are found.
Basal layer of epidermis
Dendritic cells of neural crest origin
Produce melanin, responsible for skin pigmentation
Produce more melanin rather than more cells present in darker skins
Describe Langerhans cells and where they are found.
Prickle cell layer of epidermis
Dendritic cells of bone marrow origin
Highly specialised to present antigens to T lymphocytes
Mediate immune reactions
Describe the location of the epidermal basement membrane.
Occurs at the dermo-epidermal junction below the basal layer of the epidermis
Give the cellular constituents of the dermis
Fibroblasts Blood vessels Lymphatic vessels Mast Cells Nerves
Give the components of the extracellular matric of the dermis
Collagens particularly Type 1
Elastin
Ground substance
Give 4 skin appendages
Hair follicles
Sebaceous gland
Eccrine and apocrine sweat glands
Nails
Give 4 main functions of skin
Barrier to prevent loss of fluid, heat, protein and other nutrients as well as preventing entry of harmful substances and pathogens
Sensation
Thermoregulation by both vascular and eccrine sweating methods
Psychosexual communication