1. The Integumentary System The Skin and its Appendages

2. The Skin Two main components • Epidermis • Dermis • (Hypodermis)

3. Epidermis Cells of the Epidermis • Keratinocytes • Melanocytes • Dendritic Cells (Langerhans cells)

4. Epidermis Layers of the Epidermis • Thick Skin • Stratum Basale • Stratum Spinosum • Stratum Granulosum • Stratum Lucidum • Stratum Corneum • Thin Skin • Absence of Stratum Lucidum

5. Epidermis Layers of Epidermis • Stratum Basale (germinatum) • Single row of stem cells • 10-25% melanocytes • very small amount of tactile cells

6. Epidermis Layers of the Epidermis • Stratum Spinosum • several cells thick • weblike intermediate filament network • melanin granules and dendritic cells present

7. Epidermis Layers of the Epidermis • Stratum Granulosum • Keratinization Begins • Keratohyaline granules • Lamellar granules

8. Epidermis Layers of the Epidermis • Stratum Lucidum • Only present in thick skin • 2-3 rows of clear, flat, dead keratinocytes

9. Epidermis Layers of the Epidermis • Stratum Corneum • anucleate • 20-30 cells thick • ¾ of epidermis • high keratin content • thickened, glycoprotein covered plasma membranes • loses 50k cells/min

10. Dermis Composition • Connective Tissue proper • Rich nerve and vascular supply • contains hair follicles, glands, and sensory receptors Layers • Papillary Layer • Reticular Layer

11. Dermis Papillary Layer • Thin • areolar • highly vascularized • low density (great for phagocytes) • Dermal papillae (form friction ridges in thin skin)

12. Dermis Reticular layer • 80% of Dermis • dense irregular connective tissue • blood vessel network (cutaneous plexus) • cleaveage and flexure lines

13. Appendages of the Skin • Hair and Hair Follicles • Nails • Sweat Glands • Eccrine Glands • Apocrine Glands • Sebaceous (oil) Glands

14. Appendages of the Skin Hair and Hair Follicles • Structure of hair • Structure of a hair follicle • Types and growth of hair • Hair thinning and baldness

15. Appendages of the skin Structure of a hair (fig 5.5) • Produced by hair follicles • Conists primarily of dead keratinized cells • cells contain hard keratin Regions • Shaft • Root Concentric Layers • Medulla • Cortex • Cuticle

16. Appendages of the skin Structure of a Hair Follicle (fig 5.5) • Epithelium based • Hair bulb • Hair follicle receptor • Hair papillae • Peripheral connective tissue sheath • Epithelial root sheath

17. Appendages of the Skin Types and Growth of Hair • Vellus Hair • Terminal Hair

18. Appendages of the Skin Hair Thinning and Baldness • Alopecia • True Baldness (Male Pattern)

19. Appendages of the Skin Nails (fig 5.6) • Scale-like modification of epidermis • hard keratin • free edge, nail plate, root • nail bed • nail matrix • nail folds and cuticle

20. Appendages of the Skin Sweat (Sudoriferous) Glands • Eccrine (Merocrine) Sweat Glands • Apocrine Sweat Glands

21. Appendages of the Skin Sebaceous (Oil) Glands • Simple branched alvolar glands • secrete sebum • holocrine type glands • secrete into hair follicles and occasionally pores

22. Skin Functions Protection • Chemical Barriers • acid mantle • Physical Barriers • Biological Barriers • dendritic cells, macrophages, DNA

23. Skin Functions Body Temperature Regulation Heat Loss • Vaodilation • heat loss through sweat evaporation Heat conservation • Vasoconstriction

24. Skin Functions Cutaneous Sensation

25. Skin Functions Metabolic Functions • Produces vitamin D precursor • disarm cancer causing chemicals • activate some steroid hormones

26. Skin Functions Blood Resevoir • 5% of total blood volume

27. Skin Functions Excretion • ammonia, uric acid, urea, salt, water.

28. Homeostatic Imbalances of Skin Skin Cancer • Basal Cell Carcinoma • Squamous Cell Carcinoma • Melanoma • Asymmetry • Border Irregularity • Color • Diameter • Elevation

29. Study Guide Will Post Wednesday