2. Skin Anatomy and Physiology Basics Course

3. Course Author—Dr. Patti Farris Dr. Farris is a Nu Skin Professional Advisory Board Member. She is a clinical assistant professor at Tulane and in private practice in Metairie, Louisiana. She has authored twenty-five scientific publications and is known for her expertise in the treatment of aging skin. She has appeared in over 200 health related television segments including appearances on CNN, NBC Weekend, and Regis and Kathie Lee. She has been quoted extensively in magazines (e.g., Newsweek, Allure, In Style, and Oprah Magazine ).

4. Did You Know? The skin is an organ ; in fact, it is our body’s largest organ, covering more surface area and weighing more than any other organ. Find out more about the basic functions and physiology of the skin in this course.

5. Objectives After viewing this course, you should have an understanding of the following: The six purposes of the skin. The skin’s different layers: hypodermis, dermis, and epidermis. Basic skin anatomy and physiology.

6. Introduction

7. Six Purposes of the Skin The skin certainly is a complex and fascinating organ, but it carries out some very practical and important functions for our bodies: Protection Thermoregulation Excretion Secretion Sensation Vitamin synthesis

8. Purposes of the Skin Protection: The skin serves as a protective barrier between the body and the environment.  Prevents microorganisms and other substances from entering the body.  Prevents loss of fluid from the body.  Cushions blood vessels, muscles, bones, and internal organs.  Guards against UV (ultraviolet) damage. Thermoregulation: Helps maintain a constant body temperature. Excretion: Evaporation of perspiration cools the body and eliminates some substances (i.e., salt, sebum, fatty acids) and helps to maintain the acid mantle.

9. Purposes of the Skin (continued) Secretion: Sebaceous glands secrete sebum on to the surface of the skin to fortify lipids and fatty acids within the moisture barrier and to help regulate the pH of the acid mantle. Sensation: Nerves in the skin send the brain information about the outside environment. Vitamin synthesis: In the presence of sunlight, the skin produces vitamin D, which is necessary for the absorption of calcium and phosphorus.

10. The Skin The skin is a complex organ composed of multiple layers. All layers of the skin can be divided into two main sections: Epidermis Dermis Beneath these sections is a subcutaneous layer of fat called the hypodermis. While not an official section of the skin, the hypodermis provides essential support. Epidermis Dermis Hypodermis Muscle

11. Hypodermis (deepest section) The hypodermis refers to the fat tissue below the dermis that insulates the body from cold temperatures and provides shock absorption. Fat cells in the hypodermis also store nutrients and energy. Hypodermis Fat Cells

12. Hypodermis (deepest section) The hypodermis is thickest in the buttocks, palms of the hands, and soles of the feet. As we age, the hypodermis begins to atrophy, contributing to the thinning of aging skin. Hypodermis Atrophies with age

13. Dermis (found between the hypodermis and epidermis) The dermis is a fibrous, mesh-like network of tissue that provides structure and resilience to the skin. Dermal thickness varies but is on average 2 mm thick. Major components of the dermis include the following: Collagen. Elastin. Glycosaminoglycans. Blood and lymph vessels. Specialized cells: mast cells and fibroblasts. Dermis Epidermis Blood Vessels Mast Cell Collagen Fiber Elastin Fiber Fibroblast Cell Dermal - Epidermal Junction Glycosaminoglycans

14. Epidermis (outermost section) The epidermis consists of anywhere between 50 cell layers (in thin areas) to 100 cell layers (in thick areas) and acts as a protective shield for the body. Skin cells within the epidermis are referred to as keratinocytes. Average epidermal thickness is 0.1 mm (about the thickness of one sheet of paper).

15. Epidermis (outermost section) The epidermis is composed of five horizontal layers : 1)Stratum basale 2)Stratum spinosum 3)Stratum granulosum 4)Stratum lucidum 5)Stratum corneum

16. Review Six purposes of the skin: protection, thermoregulation, excretion, secretion, sensation, and vitamin synthesis. Major layers of the skin: Epidermis – functions as a protective shield for the body. Dermis – provides structure and support. Hypodermis – subcutaneous fat serves to insulate and absorb shock. *For more detailed information on each layer of the skin and for tips on how to properly maintain the skin to achieve your desired skin care results, please reference the Skin Anatomy and Physiology Advanced course.

17. Test Your Knowledge

19. Congratulations! You have completed the Skin Anatomy and Physiology Basics course.