1. What type of tissue you observe Friday?

2. Integumentary System Integument: any covering or enclosure -Derma: skin Dermatologist?

3. Stratified squamous epithelial cells

4. Components Skin Accessory features: – Sudoriferous glands (sweat glands) – Sebaceous glands (oil glands) – Hair – Nails

5. Skin accounts for how much of your body weight? Average = 15%, 8 pounds

6. What is the skin’s square footage? Covers up to 22 square feet (2 square meters) if all spread out

7. Did you know? As a fetus, you had webbed hands and feet

8. apoptosis

9. Function Protection – Cushioning, insulation, first defense Healing Synthesizes vitamin D when exposed to UV Sensory reception Maintain homeostasis – Temperature, Waste, water Window into inner workings…examples: – Jaundice, anemia, shock, etc

10. Where is the thinnest skin located? Eyelids 0.01 to 0.015 cm thick

11. Where is the thickest skin found? Palms and heels About 0.46 cm thick

12. Labeling

14. Two types of tissue Epidermis Moisture proof Protective outer covering Thin Avascular Outer layer = dead cells Melanocytes – make melanin Constantly shedding Dermis Connective tissue Makes up majority of the skin Provides support Strength and suppleness “true” skin – stays the same throughout entire life

15. Epidermis and dermis of (a) thick skin and (b) thin skin (which one makes the difference?)

16. Epidermis: layers (on left) and cell types (on right)

17. Epidermis… Stratum germinativum Cells die as move upwards Stratum corneum Cells undergo keratinization – Tough protein – Deposited within a cell – Hardens and flattens the cells – Makes skin water-resistant

18. Dander Dead, sloughed off cells When clump together = dandruff

19. How much skin will you lose over your lifetime? About 40 pounds of skin cells are shed

20. How often is your outer layer of skin “turned over”? monthly

21. Dermis Collagen + elastin in a gel-like substance Strong and stretchable

22. Stretch marks: striae Dermal tearing Extreme stretching of the skin

23. Blister Separation of epidermal and dermal layers by a fluid-filled pocket

24. Dermis… Also contains: – Blood and lymph vessels – Nerve endings – Hair follicles – Sweat and sebaceous glands – Collagen and elastin

25. tattoos

26. Subcutaneous Layer Not part of the skin = hypodermis Loose connective tissue and adipose Insulates from extreme temperature changes in external environment Anchors skin to underlying structure – Some areas have no subcutaneous layer – connect directly to bone…

27. Subcutaneous injection Rich supply of blood vessels