Skin Flashcards
How large and weight is the skin
3.6kg
2m2
What are the three layers of the skin
Epidermis
Dermis
Subcutis
How is the skin a waterproof barrier
Tight junctions between cells in the stratum granulosum, epidermal lipids and keratin in stratum corneum form both an inside-out and outside-in barrier to water
Prevents trans epidermal wall loss
Describe the role of the epidermis
Waterproofing
Physical barrier
Immune function
Vitamin D synthesis (endocrine)
UV protection
Thermoregulation
Describe the role of the dermis
Thermoregulation
Vitamin D synthesis (endocrine)
Sensory organ
Describe the role of the subcutis
Thermoregulation
Energy reserve
Vitamin D storage
Endocrine organ
Shock absorber
What converts 7-dehyrocholestrol into previtamin D3 by UVB
Plasma membranes of epidermal keratinocytes and dermal fibroblasts
When do serum vitamin D peak
24-48 hours after exposure
What type of solubility is vitamin D
Lipid soluble - can be stored in subcutis adipocytes
How is skin the site of hormone action
Androgens act on follicles and sebaceous glands
Thyroid hormones act on keratinocytes, follicles, dermal fibroblast, sebaceous glands, eccrine glands
What does skin colour depend on
Melanin
Carotenoids
Oxy/deoxyhaemoglobin
Describe melanin
Synthesised in melanosomes within melanocytes from tyrosine
Transported via dendrites to adjacent keratinocytes
Pheomelanin - red/yellow
Eumelanin - brown/black
What do all skin types contain more of
Eumelanin than pheomelanin
How does the skin act as an immune organ
Innate and acquired immune functions
Epidermis
- langerhans cells
Dermis
- regulatory T cells
- natural killer cells
- dendritic cells
- macrophages
- mast cells
What layer is only present in thick skin
Stratum lucidum
How would you know where skin is located
If it has no apocrine sweat gland it will not be located in the axilla and genital region
What are the layers of the skin
Epidermis (outermost first)
- stratum corneum (keratinised tissue) - dead
- stratum lucidum (thick skin only) - dead
- stratum granulosa (thin layer) - alive (being to produce precursor)
- stratum spinosum
- stratum basal (germinating layer - mitosis)
Dermis
- capillary layer
- reticular layer
Hypodermis
- subcutaneous (adipose) tissue
Where are melanocytes found
Stratum basal (bottom layer of the epidermis)
What is the epithelium of the epidermis
Stratified squamous epithelium
What is acne
Pilosebaceous unit - hair follicle and associated sebaceous gland
Increased sebum production from these glands leads to the development of comedones, papules and pustules on the skin
What substances allows the skin to remain hydrated and keep slightly acidic
Natural moisturising factor
What are the 3 signs a patient would present with if the skin was penetrated by allergens
Redness
Itchiness
Dryness
What causes redness
Dilation of vessels
What causes dryness
Skin cells damaged therefore leak water
What causes itchiness
Stimulation of proprioceptors by the release of histamine
Why does acne occur
Hair follicle becomes blocked with sebum/skin cells/bacteria
What are the three types of junctions with adhere skin cells together
Adherens junctions
Desmosomes/coreneodesmosomes
Tight junctions
