1. Integument Skin and its appendages

2. Skin functions ProtectionProtection against water, bacteria, sunlight, mechanical forces, dehydration, cold, etc. Retaining body fluidsRetaining body fluids (protects against dehydration) Temperature regulationTemperature regulation by varying peripheral blood flow, sweating, hair elevation, insulation by adipose tissue under the skin Food storageFood storage and fat metabolism in the subcutaneous hypodermis Vitamin DVitamin D formation by the action of ultraviolet light Sensory appreciationSensory appreciation of the environment by nervous receptors Friction surfaceFriction surface for motor tasks involving grasping, rubbing, scratching etc. Display and communication:Display and communication: social, sexual and diagnostic

3. Skin and its appendages

4. Epidermis Canadian Ladies Give Superb Backrubs

5. “Thick” skin http://www.med.uiuc.edu/histo/medium/atlas/image/b87a/40a8.htm

6. Stratum basale or germinativum Columnar to cuboidal Basophilic Mitotic activity –Proliferate to replace lost surface cells Desmosomes and hemidesmosomes Many tonofibrils Free nerve endings –pain

7. Stratum spinosum Cuboidal/flattened TonofilamentsTonofilaments/”spines” –Keratin bundles Malpighian layerMalpighian layer –Both basal and spinosum layers –mitosis Shrinkage during processing makes them prickly look prickly

8. Stratum granulosum/lucidum GranulosumGranulosum –3-5 layers Keratohyalin granulesKeratohyalin granules –Coarse, basophilic –Packed tonofilaments convert the cells to soft keratin Lamellar granulesLamellar granules –Lipid bilayers –Eventually act as barrier LucidumLucidum –2-3 layers, seen in thick skin –Translucent,eosinophilic –No organelles or nuclei

9. Stratum corneum 15-20 layers Flattened Non-nucleated Abundance of keratin thin skin This is thin skin Lucidum is missing Often granulosum is missing

10. Keratinocyte life cycle 2-3 weeks

11. Melanocytes Basal layer Appear paler –No tonofilaments or desmosomes Synthesize melanin –Golgi participates in production of melanosomes “injected” into keratinocytes 1 in 4 to 1 in 10 of basal layer cells

12. Langerhan’s cells Present in all layers Easily seen in spinosum Bone marrow derived Pale nucleus Pale cytoplasm Cell processes (long dendrites) Antigen presenting cell –Tissue macrophage –Poorly phagocytic

13. Merkel Cell Sensory cells with vesicles In or near basal layer Clear nuclei/multilobed No tonofilaments Sensory nerve endings –Mechanoreceptors –Attach to disc shape endings of some axons that penetrate the epithelium

14. Dermis Collagen and elastin –Elastin gives skin elasticity but makes wounds gape Fibroblasts, other ct cells Papillary dermisPapillary dermis –Superficial, thin –Fine collagen fibers –Blood vessels, lymphatics –Sensory nerve endings Reticular dermisReticular dermis –Coarse, irregular fibers –Blood vessels, nerves

15. Hypodermis Fatty layer Looser connective tissue Beneath dermis

16. Taking care of Wrinkles Alpha lipoic acidAlpha lipoic acid –Antioxidant –Fat and water soluble –Enhances capacity to heal –Good for scars and wrinkles Retinoic acidRetinoic acid –Decreases fine lines –Stimulates blood flow –Even pigmentation Free radical damage –Use antioxidants –Vitamins A,C, E Sloughing process slows as we age –Alpha Hydroxy Acids UV exposure –Inflammation –Inflexible collagen and elastin –Damages blood vessels Smoking –Decreases circulation

17. Arrector pili muscle Smooth muscle fibers Inserts to hair follicle beneath sebaceous gland “goose bumps”

18. Sebaceous gland Associated with hair follicles –Except where there is no hair! Sebum has weak antibacterial properites Mitosis in basal layer Cells lost by holocrine secretion

19. Acne Proprionibacterium acnesßProprionibacterium acnesß Retin A, tretinoinRetin A, tretinoin, –Increases cell turnover –Allows sebum to be released more easily AccutaneAccutane –Inhibits sebum production Benzoyl peroxideBenzoyl peroxide –Produces oxygen –Suppresses bacterial growth SulfurSulfur –Antibacterial and drying

20. Sweat glands Merocrine (eccrine)Merocrine (eccrine) –Exocrine glands with ducts –Simple cuboidal –Covers most skin –Myoepithelial cells ApocrineApocrine –Axillae, breasts, genital –Secretions with bacteria create odor

21. Hair VellusVellus –Fine, pale hair TerminalTerminal –Coarser hair Shape of bulb determines texture of hair Overlapping layers of keratin

22. Hair in skin http://www.pantene.com/haircare/hair_twh_5.htm Everything you ever wanted to know! Information on website is not needed for exam

23. Hair bulb and follicle structure Dermal PapillaDermal Papilla –Vascular –Cells covering papilla are source of shaft MedullaMedulla –2-3 layers cuboidal cells –Vacuolated, air (may be absent) CortexCortex –Largest region –Keratinized cells with melanin CuticleCuticle –Peripheral layer of hair –Flat, scale like, clear anucleate cells Hair bulb

24. Hair bulb and follicle Inner Root SheathInner Root Sheath –Comes out when hair is plucked Outer root sheathOuter root sheath –source of new epidermal cells during wound healing –Comes out when hair is ready to fall out 1. Hair we see sticking out of head 2. What we see when pluck hair 3. What we see when hair falls out (white)

25. Bulb ultrastructure * * * *

26. Hair growth Cyclical, not constant Cells near dermal papilla source of growth AnagenAnagen –Active growth phase –Hair resistant to falling out CatagenCatagen –Relatively short –regeneration TelogenTelogen –Resting –Long phase

27. Alopecia Alopecia AndrogenicaAlopecia Androgenica –Increases cell turnover (short anagen) –Allows sebum to be released more easily –Minoxidil tretinoin spray –Minoxidil and tretinoin spray Increase size of hair follicle Prolong growth phase (anagen phase) Increase blood flow to skin Alopecia areataAlopecia areata –Unknown origin, pathologic

28. Skin cancers Basal cellBasal cell –Slow growing, rarely metastasize MelanomaMelanoma –Incredibly malignant, spreads to bone, lung Basal cell carcinomamalignant melanoma

29. Apligraf Approved by FDA for venous ulcers and diabetic foot ulcers –Very successful Shelf life of 5 days Obtained from human foreskin Organogenesis, Inc. files for bankruptcy http://www.capecodonline.com/cctimes/archives/2002/sep/27/artificialskin27.htm

30. Side by side comparison

32. Type I hypersensitivity Immediate Anaphylactic Wheal and flare –urticaria Edema of papillary layer *

33. Type III hypersensitivity Can be hemorraghic Immune complex mediated –Antibodies already present in system –Antibody/antigen complexes Many PMNs Darker red is blood in dermis Serum sickness Artery has enlarged tunica media –Fibroid necrosis *

34. Type IV blister From poison ivy Notice blister in epidermis Lymphocytes in papillary layer of dermis *

35. Type IV T cell mediated Mantoux reaction –TB tine test Cell mediated Transplant rejection *