This chapter describes the structure and functions of the epidermis and dermis, hair, and nails. In addition, the chapter outlines the types of skin cancer and risk factors for skin cancer.
- 13.1: Case Study - Skin Cancer
- 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.
- 13.2: Introduction to the Integumentary System
- In addition to the skin, the integumentary system includes the hair and nails, which are organs that grow out of the skin. Because the organs of the integumentary system are mostly external to the body, you may think of them as little more than accessories, like clothing or jewelry, but they serve vital physiological functions. They provide a protective covering for the body, sense the environment, and help the body maintain homeostasis.
- 13.3: Skin
- The epidermis is the outer of the two main layers of the skin, the inner layer being the dermis. It averages about 0.10 mm thick and is much thinner than the dermis. The epidermis is thinnest on the eyelids (0.05 mm) and thickest on the palms of the hands and soles of the feet (1.50 mm). The epidermis covers almost the entire body surface. It is continuous with, but structurally distinct from, the mucous membranes that line the mouth, anus, urethra, and vagina.
- 13.4: Hair and Nails
- Hair is a filament that grows from a hair follicle in the dermis of the skin. It consists mainly of tightly packed, keratin-filled cells called keratinocytes. The human body is covered with hair follicles except for a few areas, including the mucous membranes, lips, palms of the hands, and soles of the feet.
- 13.5: Case Study Skin Cancer Conclusion and Chapter Summary
- Skin cancer begins in the outer layer of skin, the epidermis. There are three common types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma.
Skin and its layers. Shown is a drawing of the layers of skin and associated glands and vessels (epidermis, dermis, fatty tissue, blood vessels, follicle, oil gland, sweat gland).Image used with permission (Public Domain; National Cancer Institute; NIH).