Epidermis Flashcards
histology
study of the structure and composition of skin tissue
physiology
studly of the function of skin tissue
6 primary functions
protection, absortion, secretion,sensation, excretion, and regulation of temp.
how does the skin protect us?
-melanin-from UV radiation
-acid mantle-protects against bacteria and TEWL
is slightly acidic (5.5-5.6)
What is the acid mantle made up of?
sebum, sweat (lactic acid), water and keratohyalin
how does the skin regulate temperature?
- perspiration/evaporation to cool the body,
- arrector pili muscles cause goose bumps to trap warmth in.
stratum germinativum
- AKA basal layer
- 1 layer
- 70-90% water
- Mitotic
- held together by desmosomes (cell process)
- melanocytes every 10-15 cells (skin color)
stratum spinosum
- AKA spiney layer
- 5-8 layers
- 60-70% water
- Keratin production for strength and protection
- Langerhans immune cells to detect and process foreign antigens
stratum granulosum
- AKA grainy layer
- 3-5 layers
- 20-60% water
- transitional layer between living and dead cells
- Keratohyalin- an intercellular lipid glue that replaces the desmosomes
- Membrane Coating Granules- make cell 6X stronger
stratum lucidum
- AKA clear layer
- 3-5 layers
- 10-20% water
- epidermal ridges that form our fingerprints
- thickest on palms and soles
stratum corneum
- AKA horny layer
- 15-20 layers
- 5-10% water
- desquamation occurs which is the skin natural shedding process
keratinization process
the 28 day upward migration of skin cells from the stratum germinativum to the stratum corneum
basement membrane
- AKA dermo-epidermal junction
- separates the epidermis and dermis
- transports nutrients from the vascular dermis to the -avascular epidermis.
melanin
pigment produced by the malanocyte to give us our skin color
melanogenesis
-process by which melanin is produced
-the melanosome (an organelle) is stimulated
-It uses tyrosine (amino acid) and tyrosinase (enzyme)
to produce melanin
-melanin is produced and transported from the melanocyte to the surrounding cells
3 types of UV rays
UVA
UVB
UVC
UVA
- AKA aging ray
- longest ray that penetrates deep into the dermis
- causes damage to collagen and elastin, may lead to cancer
UVB
- AKA burning ray
- second longest ray that penetrates into the epidermis
- causes sunburns, premature aging, and may lead to skin cancer
UVC
- shortest length
- does not reach the earths surface
physical sunscreen
works immediately after application to relect or scatter the suns UV radiation, eg. titanium dioxide, zinc oxide
chemical sunscreen
absorbs and traps UV radiation, eg. octinoxate
these are considered over the counter drugs (OTC)
