1. Chapter 5 The Integumentary System and Body Membranes

2. Objectives
Classify, compare the structure of, and give examples of each
type of body membrane
2. Describe the structure and function of the epidermis and dermis.
3. List and briefly describe each accessory organ of the skin
List and discuss the three primary function of the integumentary
system
Classify burns and describe how to estimate the extent
of a burn injury

3. CLASSIFICATION OF BODY MEMBRANES
Classification of body membranes (Figure 5-1)
Epithelial membranes—composed of epithelial tissue and an underlying layer of connective tissue
Connective tissue membranes—composed largely of various types of connective tissue

5. CLASSIFICATION OF BODY MEMBRANES
Epithelial membranes
Cutaneous membrane—the skin
Serous membranes—simple squamous epithelium on a connective tissue basement membrane
Types
Parietal—line walls of body cavities
Visceral—cover organs found in body cavities
Examples
Pleura—parietal and visceral layers line walls of thoracic cavity and cover the lungs
Peritoneum—parietal and visceral layers line walls of abdominal cavity and cover the organs in that cavity
Diseases
Pleurisy—inflammation of the serous membranes that line the chest cavity and cover the lungs
Peritonitis—inflammation of the serous membranes in the abdominal cavity that line the walls and cover the abdominal organs

6. CLASSIFICATION OF BODY MEMBRANES
Epithelial membranes (cont.)
Mucous membranes
Line body surfaces that open directly to the exterior
Produce mucus, a thick secretion that keeps the membranes soft and moist

7. CLASSIFICATION OF BODY MEMBRANES
Connective tissue membranes
Do not contain epithelial components
Produce a lubricant called synovial fluid
Examples are the synovial membranes in the spaces between joints and in the lining of bursal sacs

8. THE SKIN
Structure (Figure 5-2)—two primary layers called epidermis and dermis
Epidermis
Outermost and thinnest primary layer of skin
Composed of several layers of stratified squamous epithelium
Stratum germinativum—innermost layer of cells that continually reproduce; new cells move toward the surface
As cells approach the surface, they are filled with a tough, waterproof protein called keratin; eventually cells flake off of body
Stratum corneum—outermost layer of keratin-filled cells
Skin pigment—produced by deepest epidermal layer; gives color to the skin
The brown pigment melanin is produced by specialized cells in deepest epidermal layer
Blisters—caused by breakdown of union between cells or primary layers of skin

10. THE SKIN Structure (cont.)
Dermal-epidermal junction—specialized area between two primary skin layers
Dermis
Deeper and thicker of the two primary skin layers; composed largely of connective tissue
Upper papillary layer of dermis characterized by parallel rows of tiny bumps called dermal papillae
Ridges and grooves in dermis form pattern unique to each individual
Basis of fingerprinting
Improves grip for tool use and walking
Deeper reticular layer of dermis filled with network of tough, interlacing, collagenous and stretchable elastic fibers
Number of elastic fibers decreases with age and contributes to wrinkle formation
Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels

11. THE SKIN Accessory structures of the skin Hair (Figures 5-5)
Lanugo—soft hair of fetus and newborn
Hair follicle—epidermal tubelike structure required for hair growth
Hair papilla—structure from which hair growth begins
Hair root—lies hidden in follicle
Hair shaft—visible part of hair
Arrector pili—specialized smooth muscle that produces “goose bumps” and causes hair to stand up straight

13. THE SKIN Accessory structures of the skin (cont.)
Receptors (Figure 5-2)
Specialized nerve endings—make it possible for skin to act as a sense organ
Meissner’s corpuscle—capable of detecting light touch
Pacinian corpuscle—capable of detecting pressure

15. THE SKIN Accessory structures of the skin (cont.) Nails (Figure 5-6)
Produced by epidermal cells over terminal ends of fingers and toes
Nail body—visible part of nail
Root—lies in a groove; hidden by cuticle
Lunula—crescent-shaped area nearest root
Nail bed may change color with change in blood flow

18. THE SKIN Accessory structures of the skin (cont.)
Skin glands—two types
Sweat, or sudoriferous, glands
Eccrine sweat glands
Most numerous, important, and wide-spread of the sweat glands
Produce perspiration or sweat, which flows out through pores on skin surface
Function throughout life and assist in body heat regulation
Apocrine sweat glands
Found primarily in axilla and around genitalia
Secrete a thicker secretion quite different from eccrine perspiration
Breakdown of secretion by skin bacteria produces odor
Sebaceous glands
Secrete oil or sebum for hair and skin
Level of secretion increases during adolescence
Amount of secretion is regulated by sex hormones
Sebum in sebaceous gland ducts may darken to form a blackhead

19. THE SKIN Skin cancer Functions of the skin
Protection—first line of defense against:
Infection by microbes
Ultraviolet rays from sun
Harmful chemicals
Cuts and tears

20. THE SKIN Functions of the skin (cont.) Temperature regulation
Skin can release almost 3000 calories of body heat per day
Mechanisms of temperature regulation
Regulation of sweat secretion
Regulation of blood flow close to the body surface
Sense organ activity
Skin functions as an enormous sense organ
Receptors serve as receivers for the body, keeping it informed of changes in its environment

21. THE SKIN
Burns
Treatment and recovery or survival depend on total area involved and severity or depth of the burn
Body surface area is estimated using the “rule of nines” (Figure 5-8) in adults
Body is divided into 11 areas of 9% each
Additional 1% located around genitals

23. THE SKIN Burns (cont.) Classification of burns
First-degree (partial-thickness) burns—only the surface layers of epidermis involved
Second-degree (partial-thickness) burns—involve the deep epidermal layers and always cause injury to the upper layers of the dermis
Third-degree (full-thickness) burns—characterized by complete destruction of the epidermis and dermis
May involve underlying muscle and bone
Lesion is insensitive to pain because of destruction of nerve endings immediately after injury—intense pain is soon experienced
Risk of infection is increased