Skin Flashcards
What are the functions of skin?
- Thermoregulation
○ Skin temp responsive to blood flow
○ Sweat produced by eccrine and apocrine
sweat glands - Protections against injury and pathogens
- Waterproofing and fluid conservation
- Absorption of UV and Vit D production
- Sensory
- Surface for grip
What are the 3 main structures of skin?
- Epidermis
- Dermis
- Subcutis
What are the layers going down?
- Stratum cornea
- Epidermis
- Papillary dermis
- Reticular dermis
- Hypodermis
What are some apendigeal structures?
- Pilo sebaceous unit ○ Follicle ○ Hair shaft ○ Sebaceous gland ○ Pilo erecti muscle ○ Sweat gland (apocrine and eccrine)
How are keratinocytes arranged in the epidermis?
- 4 layers ○ Stratum basale ○ Spinosum ○ Granulosum ○ Corneum
What are other cell types found in the epidermis?
○ Melanocyte
○ Langerhans (APC)
○ Merkel cell (involved in sensation) - right on basement membrane
What is the basement membrane zone?
- Specialized epidermal region
- Epidermis attached to dermis via hemi desmosomes, anchoring plaques and many proteins
What is the structure and composition of the dermis/subcutaneous layer?
- Supportive connective tissue
- Made of collagen, elastin, GAGs
- fibroblasts that synthesize these proteins
- Dermal dendritic cells + other immune cells
What is the composition of the subcutaneous layer?
- Connective tissue and fats
Where in an embryo de the epidermis, dermis and melanocyte originate from?
- Epidermis - ecotderm
- Dermis: mesoderm
- Melanocyte: neural crest
Where are keratinocytes found?
- Stratum corneum
How do keratinocytes differentiate?
- Basal cell
- Prickle cell
- Granular cell
- Keratin
What is the function of keratinocytes?
- Barrier function
- Prevents allergies and prevention of eczema
How is the epidermal seal created?
Keratinocytes stuck together by seal of fats and protein
What are melanocytes?
Dendritic cells in basal epidermal layer
Where is melanin produced?
Melanosomes
How is melanin transported?
- Keratinocytes produce Melanocyte stimulating hormone (paracrine effect)
- Packaged into melanosome which move down dendritic process
- Transferred by phagocytosis to adjacent keratinocyte
- Melanonid granules form protective cap around keratinocyte nuclei and protect DANN in nucleus from UV damage
What wavelength of light stimulates melanin production?
290-320nm activates to produce more melanin
What determines skin pigmentation?
Number and size of melanosomes determines skin pigmentation
