The summer sun may feel good on your body, but its invisible UV rays wreak havoc on your skin. Exposing the skin to UV light causes photo-aging: premature wrinkling, brown discolorations, and other unattractive signs of sun exposure. Even worse, UV light increases your risk of skin cancer.
Exposure to UV radiation causes about 90% of all skin cancer cases. The connection between skin cancer and UV light is so strong that the World Health Organization has classified UV radiation (whether from tanning beds or the sun) as a Group 1 carcinogen (cancer-causing agent). Group 1 carcinogens are those carcinogens that are known with virtual certainty to cause cancer. In addition to UV light, Group 1 carcinogens include tobacco and plutonium. In terms of the number of cancers caused, UV radiation is far worse than tobacco. More people develop skin cancer because of UV light exposure than develop lung cancer because of smoking. The increase in cancer risk due to UV light is especially great if you have ever had blistering sunburns as a child or teen.
Besides UV light exposure, other risk factors for skin cancer include:
- having light-colored skin
- having a lot of moles
- being diagnosed with precancerous skin lesions
- having a family history of skin cancer
- having a personal history of skin cancer
- having a weakened immune system
- being exposed to other forms of radiation or to certain toxic substances such as arsenic
What exactly is skin cancer? Skin cancer is a disease in which skin cells grow out of control. It is caused mainly by excessive exposure to UV light, which damages DNA. Therefore, skin cancer most often develops on areas of the skin that are frequently exposed to UV light. However, it can also occur in areas that are rarely exposed to UV light. Skin cancer affects people of all skin colors, including those with dark skin. It also affects more people altogether than all other cancers combined. One in five Americans develops skin cancer in his or her lifetime.
At the end of the chapter, you will learn about the different types of skin cancer and how to identify if a growth is a mole or potentially cancerous.
Chapter Overview: Integumentary System
In this chapter, you will learn about the structure and functions of the integumentary system. Specifically, you will learn about:
- The functions of the organs of the integumentary system—the skin, hair, and nails—including protecting the body, helping to regulate homeostasis, and sensing and interacting with the external world.
- The two main layers of the skin: the thinner outer layer called the epidermis and the thicker inner layer called the dermis.
- The cells and layers of the epidermis and their functions, including synthesizing vitamin D and protecting the body against injury and pathogens, UV light exposure, and water loss.
- The composition and layers of the dermis and their functions, including cushioning other tissues, regulating body temperature, sensing the environment, and excreting wastes.
- The specialized structures in the dermis, which include sweat and sebaceous (oil) glands, hair follicles, and sensory receptors that detect touch, temperature, and pain.
- The structure and biological functions of hair, which include retaining body heat, detecting sensory stimuli, and protecting the body against UV light, pathogens, and small particles.
- The structure and functions of nails, which include protecting the fingers and toes, enhancing the detection of sensory stimuli, and acting like tools.
As you read this chapter and learn more about the skin, think about the following questions:
- What is skin cancer and how does it form?
- What are the similarities and differences of various types of cancer?
- How can people decrease their risk of getting skin cancer?