To develop an understanding of the science behind keeping skin healthy, including how it functions to protect the body and what can be done to protect skin cells from mutations caused by excessive sun exposure.
This lesson is part of the Skin Deep Project, which examines the science behind skin. Skin Deep is developed by AAAS and funded by Neutrogena. For more lessons, activities, and interactives that take a closer look at the science behind skin, be sure to check out the Skin Deep Project page.
This lesson is the first of two lessons about skin cancer using the SCI: Skin Cancer Investigation interactive. In the first lesson, Skin Cancer 1: Exposing Healthy Skin to the Sun, students are introduced to the science behind keeping skin healthy including how it functions to protect the body and what can be done to protect skin cells from mutations caused by excessive sun exposure.
Skin Cancer 2: Types, Prevention, and Detection explores what happens when healthy skin cells mutate and grow uncontrollably, leading to skin cancer. This lesson continues use of the Skin Cancer Investigation interactive by beginning with "Skin Cancer: Types."
Students, like many people, take their skin for granted. They may be unaware that it is the largest organ in their body. (The human adult is covered in about 22 square feet of skin.) However, students are usually very aware of skin problems, particularly acne and other blemishes as they relate to physical appearance. High-school students may be particularly curious about the causes and prevention of skin problems but have little knowledge about skin cancer. The Skin Deep Project takes advantage of this curiosity by introducing students in grades 6 through 12 to the science of skin, its role in protecting the body from invading microbes, regulating temperature, and sensing the environment. Through the use of project materials and related lessons, students learn what they can do to protect their skin from disease and harmful bacteria, and most importantly, skin cancer caused by the damaging effects of the sun's ultraviolet rays (UV). They will learn about the layers of healthy skin and what happens when healthy cells mutate and grow uncontrollably.
In addition to the interactive, students using this lesson will access the online book The Science Inside the Skin for in-depth information about the science of skin.
It is important for students to understand the basics about cells and cell division. Normal skin constantly produces new cells to replace older, dead cells. New skin cells result from cell division, which is normally a regulated process controlled by DNA. At times, there is a breakdown in the process when new skin cells are produced unnecessarily or dying, damaged cells do not die. This breakdown can be because of DNA damage.
Exposure to the sun without adequate protection can damage DNA in skin cells. The UV rays in sunlight cause this damage. Occasional damage to DNA is normally repaired by the body. It is the long-term exposure to UV rays that causes irreparable damage to DNA. The mutated DNA causes cells to mutate and divide uncontrollably. This uncontrolled growth of abnormal cells is skin cancer.
Students also should understand that our skin is the first line of defense for our immune system. Working in conjunction with the digestive system, our body assimilates dietary fats and oils that are secreted through the skin via tiny glands. These secreted fluids, like sweat and oil, decrease the pH on the skin surface, which kills microorganisms. Our skin also works with the excretory system to release waste products like salts and urea as well as absorb vitamins A, D, E, and K and to encourage uptake of calcium through the capillary networks in the skin.
Ideas in this lesson are also related to concepts found in the following health education standards:
- Health Education Standard 1:
Students will comprehend concepts related to health promotion and disease prevention.
6. Describe how to delay onset and reduce risks of potential health problems during adulthood.
- Health Education Standard 3:
Students will demonstrate the ability to practice health-enhancing behaviors and reduce health risks.
1. Analyze the role of individual responsibility for enhancing health.
3. Analyze the short-term and long-term consequences of safe, risky, and harmful behaviors.
4. Develop strategies to improve or maintain personal, family, and community health.
- Health Education Standard 6:
Students will demonstrate the ability to use goal-setting and decision-making skills to enhance health.
1. Demonstrate the ability to utilize various strategies when making decisions related to health needs and risks of young adults.
3. Predict immediate and long-term impact of health decisions on the individual, family, and community.
6. Formulate an effective plan for lifelong health.
To make sure students understand the basics of cell division, ask them to use the Skin Cancer Investigation student esheet to go to the Biological Basis of Heredity: Cell Reproduction and read about cell reproduction, particularly the somatic cells that are duplicated by the cell division process called mitosis. Students should use the Cell Division and Skin Cancer Investigation student sheet and record their answers to these questions:
- What is the most common form of cell replication?
- (It is mitosis.)
- What are somatic cells?
- (They are body cells, such as those in skin, hair, and muscle.)
- What is mitosis?
- (It is cell division that produces new cells for growth, repair, and replacement of older cells.)
- How many phases of mitosis do somatic cells go through and in what amount of time?
- (They go through six phases in ½ to 1½ hours.)
Next, students should use the student esheet to go to and read the "Introduction and Part 1: Skin Form and Function" in the book The Science Inside Skin. This will introduce the science behind our skin surface and lay the groundwork for the in-class discussion. You also should read these sections in the book. Some studies have shown that students have misconceptions about dark skin providing added protection from the sun, and page 5 in particular discusses skin color.
To measure students' knowledge about skin and skin cell structure, discuss these questions with students during class:
- What is the largest organ in humans?
- (It is the skin.)
- What is the primary function of our skin?
- (Its primary function is to protect our body from infection, dehydration, and to help regulate our body's temperature.)
- How else does the skin act to protect you?
- (It has nerve endings that give us our sense of touch. It tells us when we feel pain, pressure, heat, or cold. It also works with other systems in our bodies to support and maintain the health of cells, tissue, and other organs.)
- The skin has three layers. Do you know what they are?
- (They are the epidermis, the dermis, and the subcutaneous tissue.)
- Do you think skin color provides added protection from environmental elements, like the sun?
- (Dark skin provides more protection against the damaging effects of the sun's UV rays, but these rays can still penetrate cells and cause mutation.)
In this part of the lesson, students will explore healthy skin and the science behind the three layers of skin using the SCI: Skin Cancer Investigation interactive activity. Using the interactive, they will explore the effects the sun has on skin and watch animations about the benefits and risks of sunlight. They also will read about the causes and common risk factors of skin cancer.
Students should use the student esheet and follow instructions to open the online interactive and work through it, stopping to answer each series of questions. You should check for student understanding by discussing these questions in class.
- What are the types of cells in the epidermis and how are they related to each other?
- (They are basal cells, squamous cells, and melanocytes. Basal cells divide and form the squamous cells, which reside in the layer above the basal cells. The basal layer contains the melanocytes.)
- What is melanin and what is its role in the epidermis?
- (It is a pigment produced by the melanocytes. It produces the color in skin and protects the skin from the harmful effects of the sun's UV rays.)
- What is keratin and what does it do?
- (Keratin is a protein produced by squamous cells. It reinforces skin cells, which helps protect the skin from nature.)
- What are the two primary features of the dermis?
- (It contains fibers that give skin its strength and elasticity, and it contains sensory nerve cells that give skin its sense of touch.)
- Describe the subcutaneous tissue.
- (It is the bottom layer of skin made up mostly of fat.)
Effects of the Sun on the Skin
- Name the main benefits of sunlight.
- (It provides the energy necessary for life, gives light and warmth to the earth, and helps plants grow. It also can help with depression.)
- What are some of the benefits of the sun's UV rays?
- (They help our bodies produce vitamin D, which is essential for healthy bones.)
- How are these rays harmful?
- (The sun's UV rays can burn our skin, damage our eyes, cause premature aging, and lead to skin cancer.)
- How do UV rays affect normal cell division?
- (Too much sun on unprotected skin damages cellular DNA, leading to mutations that cause cells to divide uncontrollably.)
- Why do some people have a greater chance of developing skin cancer compared to others?
- (This question should reveal students' misunderstandings about dark versus light skin. Lead students in a discussion about melanin and how even dark-skinned people can get skin cancer and why.)
- What are the main differences between benign and malignant tumors?
- (The main differences are: benign tumors are not life threatening while malignant tumors are; benign tumors do not recurr while malignant tumors are recurring; benign tumors do not spread to other parts of the body while malignant tumors can spread; and benign tumors do not interfere with regular body functions while malignant tumors can.)
Skin Cancer: Common Risk Factors
- What are the five most common risk factors of skin cancer?
- (They are actinic keratosis, genetics, environment, complexion, and age.)
- Can a person change his/her risk factors, and if so, how?
- (While risk factors such as genetics, complexion, and age can't be changed, you can reduce [or modify] your risk by doing things such as wearing hats and applying sunscreen to protect your skin, and by detecting and treating actinic keratosis at an early stage.)
- How can where you live increase your chances of developing skin cancer?
- (Sunny locations and high elevations increase exposure to damaging rays.)
- How does genetics play a role?
- (A person is more susceptible to getting melanoma if there's a history of it in the family.)
- What is actinic keratosis and how does it increase the risk of skin cancer?
- (It is a rough, scaly growth that is considered precancerous. If not treated, it can become a cancerous growth.)
Discuss in class with students the dichotomy of sunlight—how the sun is necessary for healthy bones and essential to life yet can cause harm and lead to illness and even death. Our society sees tan skin as healthy skin, but it can lead to cancer. What looks like healthy skin to students versus unhealthy skin, i.e., pale skin versus weathered, wrinkly skin? Ask students to examine their own skin. What do they see? How do they envision their skin changing as they age and what can they do to protect themselves from skin cancer?
Finally, ask students to do the "Check Your Knowledge" part of the interactive as a way for them to see for themselves what they have learned.
What is the likelihood students will be diagnosed with skin cancer when adults? The lesson, Cancer Risks, describes the environmental and hereditary factors that can lead to diagnosis later in life. This lesson can be particularly important in light of new studies that show that the incidence of skin cancer has doubled since 1994.