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integumentary system
| Integumentary system | "covering" 2 regions |
| 2 regions of integumentary system | 1. epidermis 2. dermis |
| epidermis | epithelial cells outer most shield avascular+ innervated gets nutrients from dermis by diffusion |
| Dermis | much thicker and tougher. made of fibrous conn. tissue vascularized |
| Hypodermis( Superficial Facia) | deep to the skin. contains fat/adipose tissue and some areolar stores fat and anchors to muscle and allows skin to slide shock absorber, contains unwanted fat. |
| epidermis | keratinized strat. squamos -4 cell types -4~5 layers |
| 4 cells of epidermis | 1.keratinocytes 2.melanocytes 3.langerhan 4.merkel |
| Keratinocytes | -most numerous. makes keratin -increased in areas with more friction(hands/feet) -tightly bound by desmosomes -highly mitotic(dividing) -cells dead at surface -24-45 day life span |
| melanocytes | -makes melanin -make colored pigment in deepest epidermis -spidershaped. arims that touch every keratinocyte in basal layer -melanin travels to top layer..protects from uv rays |
| langerhan's cells | -rise from bone marrow. move to epidermis -asters go around keratinocytes -phagocytes that take in foreign substances& help activate immune system |
| Merkel Cell | -spiky hemisphere shape -in epidermal with dermal junction each is connected to a sensory disclike nerve called merkel disc. |
| Merkel disc | senses touch |
| Layers of Epidermis | 4-5 layers -5 in thicker skin areas s=stratum s. Basale s. Cornuem s. lucidem s. spinosum s. granulosum |
| s. basale (bottom layer) | deepest, attached to the dermis -single layer of cells. has youngest keratinocytes -germinating layer(growing) -highly mitotic -aka. Stratum germinativum -high # of melanocytes(10-25% of layer) |
| Stratum Germinativum | s. basale |
| s. Spinosum | -7 cell layers thick -contain weblike system~ Intermediate filaments -prickly name from shrinking due to diminishing nutrients yet maintains desmosomes -langerhan's cells most abundent |
| Intermediate Filaments | tension resisting bundle of keratin. - in stratum spinosum |
| s. Granulosum (granular layer) | -cells flattened, nuclie disappear& accumulate - has 2 granules -cells die above this layer |
| Granules in s. Granulosum | !. keratohyaline- keratin aggregation 2. lamellated granules- water proof glycolipids. "plated" |
| S. lucidem | -"clear layer" -only present in thick skin -thin translucent layer -flattened keratinocytes -keratohyaline attaching to keratin |
| s. coreum | -horny layer -75% of epidermis -20-30 cell layers thick mostly dead calls -aids in avoiding abrasions -dandruff comes from this -average person will shed 40 lbs/lifetime |
Created by:
britsiaj
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