Activity 5.1.1: Under Your Skin

Introduction

The skin is the largest organ inthe human body; ifyou spread it out, it would cover about twenty square feet of surface area and weigh about ten pounds. You are constantly shedding skin cells and replacing them with new ones. About 35,000 dead, flattened skin cells are shed from the skin every minute. At this rate, a person is likely to shed over nine pounds of skin every year. These fallen flakes, together with other dust and particles, contribute to the dust in our homes. Microscopic dust mites could be, at this very moment,feeding on the skin cells you shed last night.

Our skin, along with our hair and nails, make up an important human body system called the integumentary system. Theintegumentary system, especially the skin, provides the body’s first line of defense. Skin functions to keep out invaders and protect the body from injury, but it also works to keep important materials inside the body.Liquid oozes from the pores to both protect and regulate. Tiny sensors in the skin help a person feel touch, temperature and, unfortunately, pain. The skin is a living, functioning organ that plays a key role in maintaining the body’s homeostasis. The skin protects the human body, but it also allows us to connect with the outside world.

In this activity, you will build a model of a cross section of the skin. You will examine the tissues that make up skin as well as the accessory organs, such as hair follicles and sweat glands that are found within the skin’s layers. You will also investigate the way in which your skin deals with stress and how the organ changes as you age. Your skin plays a huge role in protecting and regulating the body. See if you can come up with a list of all the ways this amazing organ keeps balance in your life.

Equipment

  • Computer with Internet access
  • Laboratory journal
  • Microscope
  • Prepared slideof human skin
  • Colored pencils
  • Skin diagram

Procedure

  1. Use reference textbooks or the websites listed in Step 5 to investigate the structure of the skin. Find detailed images of the skin and its associated accessory structures.
  2. Using your skin diagram, label your diagram with the following structures. You will draw in nerves and blood vessels.
  • Epidermis
  • Dermis
  • Subcutaneous layer (fat lobules)
  • Nerves
  • Blood vessels
  • Sebaceous gland
  • Sweat gland
  • Hair follicle
  • Arrector pili muscle
  • Dermal papillae
  1. Use different colors for the different structures on your skin diagram. You can use the colors that are closest to the skin diagram you look up online.
  2. In your laboratory journal, list the parts of the skin and write one sentence next to each that describes the function of that part. The websites below may help you find information on function.
  • National Geographic : Skin
  • Health Encyclopedia: Body by Design – The Integumentary System
  • The Merck Manual’s Online Medical Library
  1. Investigate the role of the following proteins in the skin.
  • Keratin
  • Collagen
  • Elastin
  • Melanin
  1. Write a brief description of the functions of the proteins found in skin. Write what layer of the skin each of the proteins is found in.
  2. Open up your laboratory journal or notebook and find the “Tissues” concept map you created in the Activity 1.2.1. Review the four main types of human tissue – epithelial, connective, muscle and nervous.
  3. Answer conclusion question 1.
  4. Use a microscope to view the prepared slide of the human skin. Use colored pencils to draw what you see in your laboratory journal. Make sure to note the magnification.
  5. Labelthe structures you can see under the microscope. Identify the specific types of tissue that make up the epidermis and the dermis. You may need to use the Internet to find this information.
  6. Answer conclusion question 2.
  7. Go to the National Geographic Health and the Human Body webpage on Skin, accessible at .
  8. Select Stresses on the Skin on the blue bar below the main picture.
  9. View what happens to the skin when you experience a shallow cut and when you experience a deep cut. Use the scroll bar to view what happens to the skin when it is cut, when it heals and when it is repaired.
  10. In your laboratory journal, list the steps of healing that occur after a deep cut. Mention key skin layers that are affected as well as other human body systems that assist in the healing process.
  11. Return to the Stresses on the Skin main page. Click on sun exposure to investigate how your skin type responds to sunlight.
  12. Choose the skin tone that is closest to your own. Use the scroll bar at the bottom of the picture to watch what happens to the skin as sun exposure increases.
  13. In your laboratory journal, describe what happens in the skin when a person tans versus when he/she burns. Also describe the potential consequences of prolonged sun exposure.
  14. Select Effects of Aging on the blue bar below the main picture. Read the information on the main page and then click “Continue.”
  15. Use the dial at the bottom left of the screen to watch what happens to the skin over the course of a person’s lifetime.
  16. In your laboratory journal, create a timeline that describes the changes in the skin that occur from infancy to old age. Mention key skin layers as well as the proteins you researched in Step 6.
  17. Answer conclusion question 3 and 4.
  18. With your partner, brainstorm a list of functions of the skin. You have looked at the structure of the skin. But how are all these components related the skin’s function in the body? Refer back to your model for hints.
  19. Create a formal list of functions of the skin in your laboratory journal. Leave space between items in your list. You may use the Internet or textbooks to check your brainstorm list and to add more items.
  20. Circle each function on the list that relates to “protection” in the human body.
  21. Next to or below each function, list other human body systems that are involved in this function.
  22. Share your list with the class. See which group can come up with the most functions of the human skin.
  23. Answer the remaining conclusion questions.

Conclusion

  1. Based on what you know about the structure and function of different types of tissue in the body, what specific type(s) of tissue do you think make up human skin? Explain your reasoning.
  1. How does the epithelial tissue found in the epidermis of the skin differ in structure from the connective tissue found in the dermis of the skin? How is this structure linked to the function of each layer?
  1. You cut yourself slicing your morning bagel on the same morning your brother gets a wicked paper cut. Using your knowledge of the skin, explain why your injury will take much longer to heal.
  1. Explain why a person is more likely to have acne during adolescence than during young adulthood. Make sure to mention the exocrine glands that are found in the skin.
  1. Describe how other human body systems interact with the skin to protect the body.
  1. Explain how the skin helps in regulating body temperature. Mention at least two of the structures you labeled in your model.
  1. Knowing what you do about the structural components of the skin, why do you think collagen is used in cosmetic procedures to fill and hide wrinkles?
  1. How do the skin proteins – keratin, melanin, elastin and collagen – each contribute to our physical identity? How about the dermal papillae?

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Human Body Systems Activity 5.1.1 Under Your Skin – Page 1