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CHAPTER 5-THE INTEGUMENTARY SYSTEM I. THE INTEGUMENTARY SYSTEM includes the skin and its derivatives (hair, nails, glands). A. Functions of the Skin Include: 1. Covering and protecting the body 2. Regulating body temperature 3. Excreting certain wastes 4. Sensing B. The skin is the largest body organ. II. STRUCTURE OF THE SKIN A. The skin varies in thickness, depending on what part of the body it covers. B. The skin is composed of three primary layers: the epidermis, the dermis and the subcutaneous layer (hypodermis). C. The Epidermis-outer layer of the skin. 1. This portion of the skin is composed of squamous epithelial tissue which contains flat, scaly cells. 2. The epidermis also contains several sublayers of epithelial tissue known as strata. a. The Stratum Corneum is the outer layer of the epidermis and it is made up of dead cells that are covered with a thick protein known as keratin. This protein acts to waterproof the skin and to prevent the invasion of microbes into the skin. b. The Stratum Germinativum (basale)-deepest layer of the epidermis. This layer contains special stem cells that develop into all of the cells of the epidermis. These new cells push towards the surface over time. This layer also contains special cells known as melanocytes which produce and store melanin (a brown/tan pigment). 1) What is the function of melanin? D. The Dermis-deeper layer of the skin. 1. This portion of the skin is composed of thick connective tissue which contains nerves, blood vessels and lymphatic vessels. The dermis is made up of two layers (the upper Papillary Layer and the deeper Reticular Layer). 2. The dermis also contain numerous collagen fibers for strength and elasticity. 3. What are striae? E. The Subcutaneous Layer-layer between the skin and the body’s inner organs. This layer is primarily composed of adipose tissue. III. STRUCTURES ASSOCIATED WITH THE SKIN A. Hair-covers and protects many areas of the body. Hair is composed of keratinized epithelial tissue. Hair root vs. hair shaft. 1. Hair follicle-base of hair, holds the hair in place. 2. Papilla of the hair-blood vessels located at the base of the hair. C. Nails-also made up of keratin. These serve as protective coverings over the ends of the fingers and toes. 1. Nail root-anchors the nail in place, it is made up of keratinized epithelium. 2. Lunula-white, half-moon shaped structure at the base of the nail. This is an area where keratin and other cells have mixed with air. 3. The Cuticle-band of epidermis that surrounds the nail. 4. Nail Body-portion of nail we see. Contains the free edge. D. Glands of the Skin 1. Sudoriferous (Sweat) Glands-cover most of the body. These release perspiration (sweat) which acts to cool the body and remove salt related wastes from the body. a. Types of sweat glands: 1) Eccrine glands-found all over the body. 2) Apocrine glands-located in the armpits. Mammary glands are specialized types of apocrine sweat glands. b. Perspiration-primarily composed of water. It does contain salt. 1) Perspiration is the major salt removal system for the body. 2. Sebaceous Glands-secrete an oily material known as sebum into hair follicles. a. Sebum is a protective and moisturizing compound. It can also protect the skin from some bacteria. b. Sebum production is highly regulated by the sex hormones (testosterone and estrogen). 3. Ceruminous Glands-secrete a waxy material known as cebum in the ear canal. a. Cebum functions by trapping dirt and dust in the external ear canal. IV. MEDICAL WORD ELEMENTS-pages 83-86. V. PATHOLOGY A. Lesions-areas of tissue that have been damaged by injury or infection. 1. Primary vs. Secondary-page 87. B. Burns 1. 1st degree burns 2. 2nd degree burns 3. 3rd degree burns C. Neoplasm-any abnormal growth on any tissue or organ in the body. 1. Can be benign (noncancerous) or malignant (cancerous). D. Types of Skin Cancers 1. Basal Cell Carcinoma-most common type of skin cancer, least likely to spread (metastasize). Is usually removed via surgery. 2. Squamous Cell Carcinoma-is likely to spread, usually requires surgery and some form of additional therapy (radiation/chemotherapy). 3. Malignant Melanoma-most severe form of skin cancer. ABC’s of malignant melanoma: VI. DISEASES/CONDITIONS/PROCEDURES-pages 93-103.