1. Objectives  List functions of skin  Explain role of skin in temperature regulation  Describe layers of skin and characteristics  Explain factors that affect skin color  Describe accessory organs of skin

2. Chapter 5: Integumentary System

3. Functions  Protection  Temperature Regulation  Vitamin D  Sensory  Excretion

4. Epidermis Dermis Hypodermis Or subcutaneous Structure of the skin

5. Integumentary System  Consists of skin and accessory organs  Skin is 2 regions:  Dermis  Epidermis  A fatty layer lies deep (hypodermis)  Hair Follicles  Skin Glands  Nails Skin is the body’s outer covering and its largest organ.

6. Epidermis  Tissue type: Stratified Squamous Epithelium  Keratinocytes: make up 90% of cells in epidermis

7. Epidermis  No direct blood supply  Nutrients must diffuse into the epidermis

8. Cells in the Epidermis 1.Keratinocytes – produce a protein called keratin 2.Melanocytes - make dark skin pigment melanin 3.Merkel cells – associated with sensory nerve endings 4.Langerhans cells – macrophage-like dendritic cells

9. Epidermis: most superficial

10.  Stratum Corneum:  Many layers of dead cells  keratinocytes - keratin, Moisture lock  Stratum Lucidum:  Stratum Granulosum:  Statum Spinosum:  Stratum Basale:

11. Desquamification : shedding of outermost layer of a tissue Your skin constantly sheds dead cells, about 30,000 to 40,000 every minute! That’s 9 pounds per year!

12.  Stratum Corneum:  Stratum Lucidum:  Protect from UV  Thick layer  Only in frequently used areas  Stratum Granulosum:  Statum Spinosum:  Stratum Basale:

13.  Stratum Corneum:  Stratum Lucidum:  Stratum Granulosum:  Thin middle layer  Layers of keratinocytes  Initiate keratinization  Statum Spinosum:  Stratum Basale:

14.  Stratum Corneum:  Stratum Lucidum:  Stratum Granulosum:  Statum Spinosum:  Cells interlock to support skin  Resist tension  Langerhans cells (found more here than other layers)  Stratum Basale:

15.  Stratum Corneum:  Stratum Lucidum:  Stratum Granulosum:  Statum Spinosum:  Stratum Basale:  Single layer of cells  Rest on basement membrane  Cells divide continuously  Youngest cells found here  Melanocytes & Merkel cells here

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

17. Review 1. The functions of the skin include all of the following except: a. Taking in nutrients b. Preventing entry of microorganisms c. Retarding water loss d. Regulating body temperature

18. Review 1. Which layer of the Integumentary System is the foundation for the skin? a. Epidermis b. Hypodermis c. Dermis d. Stratum Corneum

19. Review 1. Which of the following is NOT considered an accessory organ of the Integumentary System? a. nails b. hair c. arteries d. glands

20. Review 1. Which of the following cell types is responsible for sensory in the epidermis? a. Langerhans b. Keratinocytes c. Melanocytes d. Merkel