1. Integumentary System

2. A system composed of multiple types of tissue: –Epithelial tissue –Connective tissue –Muscle tissue –Nervous tissue Also includes, hair and nails.

3. Integumentary System The function of the system is: – to protect the body – maintain homeostasis – regulate temperature – respond to stimuli Skin makes up the largest portion of the system.

4. Structure of Skin Your skin is composed of two main layers: Epidermis Dermis

5. The epidermis is the outermost layer made of two parts: 1.Exterior Layer: 25-30 layers of dead skin cells that are continually shedding 2.Interior Layer: living cells that divide in order to replace dead cells, contains melanin Structure of Skin Epidermis

6. Melanin is a pigment that accounts for the differences in skin color among people. Melanin also helps protect underlying cells from UV light, which can lead to the development of skin cancer. Structure of Skin Epidermis

7. Outer Layer of Epidermis

8. Fun Fact! Every 4 weeks, all cells of the epidermis are replaced by new cells! That’s a whole lot of skin…

9. A man standing behind 21 square feet of skin substitute – the amount covering an average human body!

10. The epidermis on your fingers, palms, toes and soles of your feet formed ridges and grooves before your were born. The ridges are important for gripping because they increase friction. Structure of Skin Epidermis

11. These fingerprints and footprints are often used to identify individuals since each person has a unique set. The shapes of the fingerprints form in the womb and can depend on nutrition, position in the womb and growth rate. Structure of Skin Epidermis

12. Fun Fact! Identical twins DO NOT have the same fingerprints!

13. Structure of Skin Your skin is composed of two main layers: Epidermis Dermis

14. The dermis is the inner, thicker portion of the skin. The thickness varies between parts of the body. Structure of Skin Dermis

15. The dermis contains: Oil glands Sweat glands Blood Vessels Nerves Hair Follicles

16. Structure of Skin Dermis Blood Vessels- deliver materials to cell, pick up wastes Nerves/receptors- send messages to your brain to explain touch, heat, etc Hair- protect skin, provide insulation Sweat glands- cool and clean body surface Oil glands- usually connected to hair follicle, keeps skin and hair from drying out, protect from pathogens

17. Below the dermis is a layer of fat which helps the body absorb impact, retain heat, and store energy. Structure of Skin Dermis Fat Layer Or Hypodermis

18. Protection- your skin is the first line of defense from pathogens and UV rays. Protect your skin by wearing sunscreen EVERY day! Function of Skin

19. Homeostasis- your skin regulates your body temperature by increasing or decreasing the blood flow Also, when your body heats up your sweat glands release liquid to cool your skin Function of Skin

20. Your skin has nerve endings and receptors for touch, pain, and heat. Your receptors send messages to your brain/spinal cord so that you can move or make adjustments. Function of Skin

21. Other animals use skin for gas exchange Other Animals Skin

22. Section Check

23. Section 1 Check Question 1 What part of the skin responds to external stimuli such as heat and pressure? D. muscle tissue C. connective tissue B. nervous tissue A. epithelial tissue

24. Section 1 Check The answer is B, nervous tissue. Nerve endings

25. Section 1 Check Question 2 Why is your skin considered an organ? Answer Skin is composed of cells and tissues. A group of tissues that work together to perform a specialized function are called an organ.

26. Section 1 Check Question 3 The thicker portion of skin that is composed of blood vessels, nerves, nerve endings, hair follicles, sweat glands, and oil glands is called the _______. D. fat tissue C. epidermis B. subcutaneous layer A. dermis

27. Section 1 Check The answer is A, dermis.

28. Section 1 Check Question 4 What gives skin color? D. fat tissue C. cellulose B. melanin A. tanning

29. Section 1 Check The answer is B, Melanin.

30. Section 1 Check Question 5 Which is not a function of your skin? D. Allowing water to escape through pores. C. Preventing pathogens from entering the body B. Protecting your organs from harm. A. Maintaining homeostasis.

31. Section 1 Check The answer is D. Your skin protects your body from harm, regulates temperature, maintains homeostasis and responds to stimuli.