Anatomy 9/18/06
Terms
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- Skin (general)
-
-largest bodily organ
-part of the integumentary system
-has 3 layers (epidermis, dermis, and subcutaneous)
-avg thickness= 2mm (half for eyelids, lips, gentialia; twice for palms and soles of feet) - Skin (purpose)
- 1. protects (almost impermeable layer) 2. resists water movement (lose 500 cc's per day through evaporation) 3. temp regulator 4. metabolic regulation 5. initiates immune system 6. sensory receptors 7. excretion (uses sweat)
- Skin (epidermis)
- outermost layer (epithelial tissue; little or no matrix)
- Skin (dermis)
-
-largest layer
-middle layer
(connective tissue; blood vessels)
contains papilary (outer) and reticular (inner) layers - Skin (subcutaneous)
-
-known as the hypodermis
-innermost layer (loose connective tissue)
-contains alot of blood vessels - Skin (sensory receptors)
- -lets you communicate w/ the outside world
- Skin (metabolic regulation)
-
-uses UV rays from sun to produce vitamin D3
- in order to absorb calicum through intestinal wall - Epidermis (Stratum Bassalic)
-
-bottom layer of epidermis
-HIGHLY MITOTIC
-contains skin stem cells
-give rise to keratinocytes (maunfactures keratin) - Epidermis (Keritinocytes)
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-basic skin cells
-90% of epidermis - Epidermis (Melanocytes)
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-produce melanin
-gives pigment (color and tone of skin)
-8% of epidermis - Epidermis (Langerhens)
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-phagocytic macrophage
-engulfs non-functional cells and invaders
-protects dermis
-starts immune response - Epidermis (Tacitle cells)
-
-(Merkel)
-sensory cells
-very fine sense of touch
-squeeses the cells together to Merkel
-lets you read braille, feel difference in fine fabrics - Epidermis (cell erosion/production)
-
-surface cells constantly get worn away
-constantly producing new cells
-Keratinocytes start to die in stratum granulosum and fill with keratin - Epidermis (Stratum Lucidum)
-
-2-3 cell layers thick
-only found on palms and soles of feet
-gives pale pigment to hands and feet
-filled with cleidin (a modified melanin) - Epidermis (stratum Corneum)
-
-30-50 cells thick
-flat squamous cells
-almost impermeable
-Cornification - Epidermis (Cornification)
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-staggering and overlapping of cells
-prevents H2O and viruses from going all the way through the epidermis - Epidermis (stratum spinosum)
-
-alive
-located in direct blood supply - Epidermis (Gradulosum)
-
-cells are oxygen deprived.
-die at top of layer and become kerantized
-lose structural integrity - Epidermis (Melanin)
-
-protects against UV rays by absorption
-exocytosis gives melanin to keratin to cover
-too much= skin cancer