Chapter 5 Video Lecture Notes.docx - Integumentary System...

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Integumentary SystemWhat is it?SkinHairNailsSweat glandsSebaceous glandsWhat’s the structure of skin?
3. Dendritic (Langerhans):Star shaped macrophage that patrol deep ED4. Tactile (Merkel):Sensory receptorsEpidermis (ED): Layers1. Stratum basale (bay-say-lee)1. Base layer, firmly attached to dermis2. Single row of stem cells that actively divide (mitosis -- 2 daughter cells, 1 to surface in
25 days, other to remain)3. Lots of melanocytes (10-25%)2. Stratum spinosum1. Prickly layer (from keratinocytes), melanosomes, and dendritic cells2. Several layers thick, cells contain web system of intermediate pre-keratin filaments attached to desmosomes to resist tension and pulling3. Stratum granulosum1. 4 - 6 layers of flattened cells (thin layers)2. Cell appearance changes; cells flatten, nuclei and organelles disintegrate → keratinization begins & cells accumulate lamellar granules (slows water loss)3. Cells above this layer die because they are too far from capillaries to survive4. Stratum lucidum (thick skin only)1. Thick, translucent bands of 2 - 3 clear, flat dead keratinocytes5. Stratum corneum1. Horny layer: 20 - 30 rows of flat, ANUCLEATED, keratinized, DEAD CELLS, ¾ of skin thickness2. Function: protects deeper cells from environment, prevents water loss, protects from abrasion and penetration, acts as a barrier against biological, chemical, and physical assault
Dermis -- fibrous connection tissue (strong & flexible), vascular, deep to epidermis:CellsFibroblastsMicrophagesMast cellsWhite blood cellsStructure

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