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1 Biology 1 of 23

2 36 3 The Integumentary System 2 of 23

3 (The skin, hair, nails, and a variety of glands make up the integumentary system. The skin is the largest organ in the body.) 3 of 23

4 What are the functions of the integumentary system? 4 of 23

5 A. The integumentary system: 1. serves as a barrier against infection and injury. 2. helps to regulate body temperature. 3. removes waste products from the body. 4. provides protection against ultraviolet radiation from the sun. 5 of 23

6 The Skin B. The Skin 1. two main layers: a. epidermis b. dermis. 2. Hypodermis: a. layer of fat and connective tissue b. insulates the body 6 of 23

7 The Skin Structures of the Skin Hair follicle Sweat pore Nerves Blood vessels Hair Sebaceous gland Epidermis Dermis Muscle Sweat gland Hypodermis Fat 7 of 23

8 The Skin C. Epidermis 1. outer layer of the skin. 2. Made up of 2 layers: a. outer layer-- dead cells. b. inner layer -- living cells. 8 of 23

9 The Skin (Cells in the inner layer undergo rapid cell division, producing new cells that push older cells to the surface of the skin. Older cells flatten and their organelles disintegrate. Older cells also begin making keratin, a tough, fibrous protein. When these cells die, they form a waterproof covering on the skin s surface.) 9 of 23

10 The Skin 3. Keratin: tough, fibrous protein, helps skin be waterproof 4. Melanin: a. dark brown pigment b. protects skin from sun damage c. amount melanin present produces different skin colors 10 of 23

11 The Skin D. Dermis 1. inner layer of the skin 2. contains: * collagen fibers, * blood vessels, * nerve endings, *glands, *sensory receptors, *smooth muscles *hair follicles. 11 of 23

12 The Skin 3: contains 2 types of glands: a. sweat glands- Produces sweat to help cool the body b. sebaceous (oil) glands- Produces sebum, spreads out skin surface to keep it flexible and waterproof 12 of 23

13 Hair and Nails E. Hair (Hair covers most body surfaces) 1. Function: a. protects scalp from uv light from sun. b. provides insulation from cold. c. prevents dirt and other particles from entering the body. 13 of 23

14 Hair and Nails (Hair is produced by hair follicles, which are tubelike pockets of epidermal cells that extend into the dermis. An individual hair is a column of cells that have filled with keratin and died. The oily secretions of sebaceous glands help maintain the condition of each individual hair.) 14 of 23

15 Hair and Nails F. Nails 1.grow from rapidly dividing cells in the nail root. (white half moon at base of nail) 2.During cell division, cells fill with keratin to produce a nail 3. cover/ protect the fingertips and toes. 15 of 23

16 36 3 Continue to: - or - Click to Launch: 16 of 23

17 36 3 Keratin provides a. insulation. b. a waterproof covering. c. pigmentation. d. protection from UV radiation. 17 of 23

18 36 3 The dermis contains two types of glands: sweat glands and a. sebaceous glands. b. pigment glands. c. hair follicles. d. dermal glands. 18 of 23

19 36 3 All of the following are found in the dermis EXCEPT a. nerve endings. b. blood vessels. c. sebaceous glands. d. melanocytes. 19 of 23

20 36 3 The function of melanin is to a. help control the rate of heat loss by the skin. b. produce sweat. c. produce a waterproof covering on the surface of the skin. d. absorb harmful UV radiation. 20 of 23

21 36 3 The basic structure of human hair and nails is a. melanin. b. sebum. c. keratin. d. dermal cells. 21 of 23

22 END OF SECTION

The Integumentary System Dr. Ali Ebneshahidi

The Integumentary System Dr. Ali Ebneshahidi The Skin The integument system consists of the skin (cutaneous membrane) and its accessory organs. The skin is composed of three layers of tissue: the outer