Transcript WARM UP 11/21

Warm Up 11/17
1. 3 functions of skin
2. 2 layers of skin
3. 4 things skin protects against
4. what is homeostasis
5. how does the skin helps us lose
heat?
NOTES Ch 5 11/17
Epidermis
1. EPIDERMIS
* outer layer
* thin
* avascular
* epithelial
tissue
EPIDERMIS
3 types of cells:
1. KERATINOCYTES – makes cells hard and
tough
2. MELANOCYTES – produce melanin; gives
skin color, blocks UV
3. LANGERHAN’S CELLS – destroys microbes
4 layers of the epidermis
1. STRATUM CORNEUM – top layer
* dead stratified squamous cells
* cytoplasm replaced by keratin
* prevents drying out
* cells constantly flaked off
CALLUS – outward thickening of this
layer due to friction –protective
response
CORN – inward thickening due to friction
(Stratum lucidum) – in thick skin
2. STRATUM GRANULOSUM – 2nd layer
* makes keratin
3. STRATUM SPINOSUM – 3rd layer
* Langerhan’s cells
4. STRATUM BASALE – bottom layer
* has melanocytes
* mitosis happens here fast
* gets nutrients from the dermis
below it
EPIDERMAL CELL CYCLE
- Cells produced in basale
- Move up
- Keratin added in granulosum
- Cells die
- Move up to corneum
- Shed off - DESQUAMATE
( about 35 days)
Dermal-Epidermal Junction
• Area between the epidermis and dermis
• Glue-like basement membrane
BLISTERS – when this junction pulls
apart or is irritated
(burns, friction, or chemicals)
1. Stratum
corneum
2. Stratum
granulosum
3. Stratum
spinosum
4. Stratum basale
SKIN COLOR
• Produced by MELANOCYTES in the
epidermis STRATUM BASALE layer
• All races have about the same concentration
of melanocytes
• Amount of MELANIN produced gives the
different SKIN COLOR
• Melanin can be BLACK, BROWN, OR
YELLOW TINTS
2 FACTORS THAT CAUSE
SKIN COLOR
1. GENETICS
* Each person inherits 4-6 pairs of
genes for melanin production (dark
skin = more production)
* ALBINISM – genetic disorder where
no melanin is produced
2. ENVIRONMENT
* Sunlight, UV light, X-rays – cause
temporary melanin production (tan)
* melanin darkens in sunny locations
as a defense mechanism to protect
tissues under it
FRECKLES – concentrated spots of
melanin
VITILIGO – patches of light and dark in
areas
AGE SPOTS – melanin collecting in spots
SKIN CANCER