Chapter 4

1. Chapter 4 The Integumentary System

2. Chapter 4The Integumentary System Multimedia Asset Directory Slide 27 Integumentary Repair Animation Slide 57 Eczema Movie Slide 74 Skin Cancer Movie

3. The Integumentary System • Contains the largest organ in the body, the skin • Contains smaller organs that lie within the skin • Hair • Hair follicles • Nails • Oil glands • Sweat glands • Sensory receptors • The skin is engaged in a constant battle with infectious agents

4. Figure 4.1: Anatomy of the skin Illustration of a section of skin showing key structures. Source: Icon Learning Systems.

5. Prefixes • a- = without • an- = without • ep- = upon, on, over • epi- = upon, on, over • intra- = within • per- = through • sub- = beneath

6. Word Roots • aden = gland • auto = self • bi = life • cutane = skin • crypt = hidden • derm, derma, dermat = skin • eryth, erythr = red • heter = other • hidr = sweat

7. Word Roots (cont.) • kerat = horny tissue, outer hard layer • leuk = white • myc = fungus • necr = death • onych = nail • pachy = thick • rhytid = wrinkles • scler = thick • seb = sebum, or oil • trich = hair • xer = dry

8. Suffixes • -ectomy = surgical removal, or excision • -ia = condition of a diseased or abnormal state • -is = pertaining to • -itis = inflammation • -malacia = softening • -opsy = view of • -osis = condition of

9. Suffixes (cont.) • -ous = pertaining to • -phagia = eating or swallowing • -plasty = surgical repair • -rrhea = excessive discharge • -tome = instrument used to cut material

10. Anatomy and Physiology • The skin establishes a physical barrier that protects against • Loss of body fluids • Damage due to physical injury or UV light • Invasion by microorganisms • The skin helps regulate body temperature by forming an insulating blanket around the body • Sweat glands assist in temperature control when it’s hot and help remove waste materials • Skin provides valuable information about the outside environment

11. The Skin • Covers your body to protect it from the outside environment • As a protective and insulating cover, it helps your body to maintain homeostasis • Two distinct layers • Epidermis • Dermis

12. Epidermis • Thin, outermost layer of the skin • Includes many layers of cells that are packed tightly and do not permit blood vessels to penetrate • The deepest layer is responsible for new cell production • Cells are replaced every 7–10 days as new cells push older cell layers upward

13. Figure 4.2: Layers of the epidermis

14. Epidermis • As cells approach the skin, they become filled with the tough, waterproof protein, keratin, and eventually die • The superficial layers of the skin are filled with mostly dead cells composed of keratin • Keratin is a major component of the hair and nails

15. DNA within the Epidermis • The color of skin is determined by the genes within the DNA of specialized skin cells located deep within the epidermis • These genes regulate the amount of pigment protein produced by these cells • The protein is a brown color and is called melanin • The more melanin produced, the darker the skin becomes • Melanin protects your skin from UV light which can damage DNA and lead to skin cancer • Exposure to UV light stimulates the production of melanin to increase this protective shield, this effect is called tanning

16. Dermis • Thick, deep layer of the skin • Composed of connective tissue which contains blood vessels and is rich in the protein collagen • Collagen serves as a glue to bind the dermis with thick, tough fibers and with the underlying layer of tissue known as the subcutaneous layer • Subcutaneous layer is comprised of mostly fat

17. Dermis (cont.) • The dermis also contains the protein elastin • Gives skin the ability to stretch and retract • Aging skin has decreased elastin production causing skin to lose its elasticity • The dermis contains the following accessory organs • Hair • Hair follicles • Nails • Oil glands • Sweat glands • Sensory receptors

18. Hair • The skin covering your body is filled with hair • The only body areas lacking hair are • Palms of the hands • Soles of the feet • Eyelid surfaces • Hair provides some protection from UV light and assists in the sensation of touch • Hair consists of the hair root and hair shaft • Hair root is embedded in the skin • Hair shaft is above the skin surface

19. Figure 4.3: The hair and hair follicle, and associated structures Source: Icon Learning Systems.

20. Hair Follicles • The hair follicle is a supportive sheath of epithelial cells that surrounds most of the hair root • It is a downward growth of the epidermis into the dermis which surrounds the hair root • The deepest part contains layers of cells that divide to produce new hair cells • The hair cells are pushed up by younger hair cells and when moved toward the skin surface, they undergo death and replacement by keratin • As a result of this replacement the hair shaft is composed mainly of keratin and is nonliving • Hair receives its color by melanin production

21. Nail • Formation begins in the epidermis, and the nails fill with keratin and die as they are pushed upward and forward • The white area is called the lunula • The visible pink area is the nail body • The cuticle is a flap of dead epidermal cells at the proximal edge of the nail • An alternate word for cuticle is eponychium

22. Figure 4.4: Nail structure, side view and cross sectional view Source: Icon Learning Systems.

23. Sebaceous Glands • Sebaceous glands are also called oil glands • The fluid released from these glands is an oily fluid that lubricates the skin and hair • This oily fluid is called sebum • Sebum is a mixture of lipids, salts, water, and cholesterol • Sebaceous glands are connected to a hair follicle by a short duct that carries sebum • When these ducts become plugged by sebum, it is commonly called a blackhead, and it may lead to a pimple if bacteria grows

24. Sweat Glands • Widely distributed throughout skin in great numbers • They secrete a watery substance called sweat • Composed of water, salts, and urea • Sweat helps maintain body temperature • Aids the kidneys in the elimination of metabolic wastes

25. Sensory Receptors • The skin contains millions of microscopic structures known as sensory receptors • Each receptor is a specialized ending to a neuron and is capable of initiating a nerve impulse when stimulated by • Change in temperature • Pressure change • Movement of nearby tissues • Damage to nearby cells • The receptors are physically connected to the brain by way of sensory nerves

26. Sensory Receptors (cont.) • Once the impulse is received and interpreted by the brain, the sensations of heat and cold, pressure and fine touch, and pain may be brought to awareness • The presence of sensory receptors enables you to detect changes in the outside world, and gives the body the ability to respond to these changes

27. Integumentary Repair Animation Click here or on the screenshot to view the animation. Return to Directory

28. Word Root and Terms Formed from the Word Root • colla = glue • Collagen • cutane = skin • Subcutaneous • derm, derma, dermat = skin • Dermis • Epidermis • Hypodermic • Intradermal

29. Word Root and Terms Formed from the Word Root • elast=change shape • Elastin • onych=nail • Eponychium • ker=horn • Keratin • Keratogenic • melan=black, dark • Melanin • seb=oily fluid • Sebaceous glands • Sebum

30. Other Important Terms • Cuticle • Hair • Hair follicle • Hair root • Hair shaft • Nail • Lunula • Sensory receptor • Sweat glands

31. Integumentary System Specialization • Dermatology • The medical field that specializes in the health and disease of the integumentary system • Dermatologist • A physician specializing in dermatology

32. Symptoms and Signs of the Integumentary System • Abrasion • A skin wound caused by scraping • Abscess • A collection of pus from a localized infection • Alopecia • A loss or lack of scalp hair; also called baldness • Cellulite • A local uneven surface of the skin caused by fat deposition, usually in the thighs and buttocks

33. Figure 4.5: Alopecia or balding Source: BioPhoto Associates/Photo Researchers, Inc.

34. Symptoms and Signs of the Integumentary System (cont.) • Cicatrix • A scar • Comedo • An elevated lesion formed from the buildup of sebum and keratin; also called a pimple • Contusion • An injury to the skin causing discoloration and swelling without breaking the skin surface; also called a bruise • Cyst • A closed sac or pouch containing fluid

35. Symptoms and Signs of the Integumentary System (cont.) • Diaphoresis • Profuse sweating • Edema • Swelling caused by accumulation of fluid • Erythema • General term for redness of the skin • Fissure • A narrow break or slit in the skin

36. Symptoms and Signs of the Integumentary System (cont.) • Furuncle • A localized skin infection originating from a hair follicle • Induration • The formation of local hard areas on the skin or elsewhere • Jaundice • An abnormal yellow coloring of the skin; also called xanthoderma • Keloid • An overgrowth of scar tissue

37. Figure 4.6: Furuncle Courtesy of Jason L. Smith, MD.

38. Figure 4.7: Keloid Courtesy of Jason L. Smith, MD.

39. Symptoms and Signs of the Integumentary System (cont.) • Laceration • A torn or jagged wound • Lesion • A change in tissues due to disease or injury • Macule • A discolored flat spot, such as a freckle • Nevus • A circumscribed pigmented area, a mole, or a birthmark; plural form is nevi

40. Figure 4.8: Nevus Courtesy of Jason L. Smith, MD.

41. Symptoms and Signs of the Integumentary System (cont.) • Pallor • Abnormal lack of skin color; paleness • Papule • A small, solid, circumscribed skin elevation • Petechia • A pinpoint skin hemorrhage; the plural form is petechiae • Pruritus • Itching

42. Figure 4.9: Purpura Courtesy of Jason L. Smith, MD.

43. Symptoms and Signs of the Integumentary System (cont.) • Purpura • A purple-red discoloration resulting from hemorrhage into the skin • Pustule • A small circumscribed skin elevation that contains pus • Ulcer • An eroded lesion of the skin or mucus membrane • Urticaria • Skin eruption usually caused by an allergic reaction to foods, infection, or injury, also called hives

44. Symptoms and Signs of the Integumentary System (cont.) • Verruca • A small circumscribed elevation caused by a virus; also called a wart • Vesicle • A small elevation of the epidermis that contains fluid; also called a blister • Wheal • A temporary, itchy elevation of the skin, usually with a white center and red perimeter; also called a welt

45. Figure 4.10: Common skin signs Each of the illustrations depict a section through skin. Source: Pearson Education.

46. Diseases and Disorders • Acne • An inflammatory eruption of the skin caused by bacterial infection of sebaceous glands and ducts • Actinic keratosis • A precancerous skin condition caused by exposure to sunlight marked by overgrowths of the outer epidermal layer • Albinism • A genetic condition characterized by the lack or reduction of melanin; an individual with this condition is referred to as albino

47. Figure 4.11: Acne Courtesy of Jason L. Smith, MD.

48. Diseases and Disorders (cont.) • Basal cell carcinoma • A tumor arising from the epithelium of the epidermis; it can spread locally if not treated, but seldom metastasizes • Carbuncle • A skin infection composed of a cluster of boils caused by staphylococci bacteria • Cellulitis • Inflammation of connective tissue caused by infection

49. Figure 4.12: Basal cell carcinoma Courtesy of Jason L. Smith, MD.

50. Figure 4.13: Carbuncle Courtesy of Jason L. Smith, MD.