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Unformatted text preview: Skin Function of Skin: • Physical barrier • Insulation • Storage (lipids, water) • Protection 6,000 sq inches of skin, 6 lbs 1/3 blood supply For the most part, constantly regenerated. 3 layers (from outside to inside): • Epidermis- outermost layer, Made of 5 layers, No blood supply and no nerve endings • Dermis- true skin, thickest and largest • Subcutaneous- fat reserve **as we age, the layers get thinner. In females, especially the dermis gets thinner wrinkling Epidermis: Stratum Corneum dead, keratinized cells constantly getting shed off, slothed off and new cells are replacing them constant turnover Stratum Lucidum few layers thick drastic structural changes nucleus, organelles start to disappear, cells are almost dead, but have keratin on them that help protect other layers of cell. Stratum Granulosm as the keratinocytes migrate up, they begin to undergo apoptosis, and increase the production of keratin. start to see granules in the cells. keratin helps make skin water resistant, trap UV rays Stratum Spinosum desmosomes- present between cells, form junction between cells, prevent cells from entering lower layer (1 st defense system) Stratum Germinativum (Basale) cells are made here and migrate to the upper layers. only layer with mitotic division Basale Keratinocytes- make up 95% of cells in layer. Keep replicating. Make keratin melanocytes- produce pigment, melanin langerhan cells- immune cell, dendritic cell, sample antigens and present to macrophages, B and T cells (2 nd defense system) Dermis main blood supply made up of connective tissue largest thickest later 95% white collagen –gives tensile and strength 5% elastin- helps give skin elasticity hair follicles, sweat glands, nerve endings, blood vessels, sebaceous glands subcutaneous layer adipose layer energy source insulation 3 main layers Dermis Epidermis Subcutaneous How Aging Affects Different Layers of Skin: • Decreased density and structural changes in all layers • Not much research on skin until mid to late 80’s because people were not as concerned with the skin because people don’t really die from skin disorders • Once people started researching, realized its important because o Pathologies that occur on skin reflect what is going on in internal organs Aging in skin may reflect aging of internal organs • 1 st study- 1963 Tindell & Smith o Looked at 165 individuals 65+ o Given full physical exam by physician and all were in good health Physical exams do not include good detailed look at the skin o Wanted to look at structural changes in the skin and found significant changes even though they were considered “healthy” o Findings: 100% had benign tumors 80% had seborrheic keratosis- 100% had lentigo (single)/lentigines (plural), senile freckles...
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This note was uploaded on 02/25/2012 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.
- Fall '08