1. PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 5 The Integumentary System

2. Copyright © 2010 Pearson Education, Inc. Skin (Integument) Skin- Cutaneous membrane -Covers external surface of the body; largest organ in body in surface area and weight (16% of total body weight, 10-11 lbs) -2 sq meters (22 sq ft) -1-2 mm thick in most cases -2 distinct layers-dermis and epidermis

3. Copyright © 2010 Pearson Education, Inc. Skin (Integument) Functions of skin: 1. Thermoregulation-contributes to homeostasis by regulating body temp (thru sweating or blood vessel dilation/constriction at surface) 2. Blood reservoir-8-10% of resting blood supply found in dermis 3. Protection-for underlying tissue by keratin from microbes, abrasion, heat, chemicals 4. Excretion/Absorption-excrete organic wastes, salts, CO 2, water; absorbs Vit A D E K 5. Synthesis-Vit D 3, steroids 6. Detection-touch, pressure, pain, temp

4. Copyright © 2010 Pearson Education, Inc. Skin (Integument) Consists of three major regions 1.Epidermis—superficial region 2.Dermis—middle region 3.Hypodermis (superficial fascia)—deepest region Subcutaneous layer deep to skin (not technically part of skin) Mostly adipose tissue

5. Copyright © 2010 Pearson Education, Inc. Figure 5.1 Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial fascia) Dermal papillae Pore Subpapillary vascular plexus Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Nervous structures Sensory nerve fiber Pacinian corpuscle Hair follicle receptor (root hair plexus) Cutaneous vascular plexus Adipose tissue

6. Copyright © 2010 Pearson Education, Inc. Epidermis Keratinized stratified squamous epithelium Cells of epidermis Keratinocytes—produce fibrous protein keratin Melanocytes 10–25% of cells in lower epidermis Produce pigment melanin Epidermal dendritic (Langerhans) cells—macrophages that help activate immune system Tactile (Merkel) cells—touch receptors

7. Copyright © 2010 Pearson Education, Inc. Figure 5.2a Dermis Stratum corneum Most superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum granulosum Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. Stratum spinosum Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells. (a)

8. Copyright © 2010 Pearson Education, Inc. Layers of the Epidermis: Stratum Basale (Basal Layer) Deepest epidermal layer firmly attached to the dermis Single row of stem cells Also called stratum germinativum: cells undergo rapid division Journey from basal layer to surface Takes 25–45 days

9. Copyright © 2010 Pearson Education, Inc. Layers of the Epidermis: Stratum Spinosum (Prickly Layer) Cells contain a weblike system of intermediate prekeratin filaments attached to desmosomes Abundant melanin granules and dendritic cells

10. Copyright © 2010 Pearson Education, Inc. Layers of the Epidermis: Stratum Granulosum (Granular Layer) Thin; three to five cell layers in which the cells flatten Keratohyaline and lamellated granules accumulate

11. Copyright © 2010 Pearson Education, Inc. Layers of the Epidermis: Stratum Lucidum (Clear Layer) In thick skin Thin, transparent band superficial to the stratum granulosum A few rows of flat, dead keratinocytes

12. Copyright © 2010 Pearson Education, Inc. Layers of the Epidermis: Stratum Corneum (Horny Layer) 20–30 rows of dead, flat, keratinized membranous sacs Three-quarters of the epidermal thickness Functions Protects from abrasion and penetration Waterproofs Barrier against biological, chemical, and physical assaults

13. Copyright © 2010 Pearson Education, Inc. Figure 5.2b Melanocyte Melanin granule Tactile (Merkel) cell Sensory nerve ending Epidermal dendritic cell Dermis Keratinocytes Stratum corneum Most superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum granulosum Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. Stratum spinosum Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells. Desmosomes (b)

14. Copyright © 2010 Pearson Education, Inc. Dermis Strong, flexible connective tissue Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells Two layers: Papillary Reticular

15. Copyright © 2010 Pearson Education, Inc. Figure 5.1 Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial fascia) Dermal papillae Pore Subpapillary vascular plexus Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Nervous structures Sensory nerve fiber Pacinian corpuscle Hair follicle receptor (root hair plexus) Cutaneous vascular plexus Adipose tissue

16. Copyright © 2010 Pearson Education, Inc. Layers of the Dermis: Papillary Layer Papillary layer Areolar connective tissue with collagen and elastic fibers and blood vessels

17. Copyright © 2010 Pearson Education, Inc. Layers of the Dermis: Reticular Layer Reticular layer ~80% of the thickness of dermis Collagen fibers provide strength and resiliency Elastic fibers provide stretch-recoil properties

18. Copyright © 2010 Pearson Education, Inc. Skin Markings: Friction Ridges Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints

19. Copyright © 2010 Pearson Education, Inc. Figure 5.4a Friction ridges (a) Openings of sweat gland ducts

20. Copyright © 2010 Pearson Education, Inc. Skin Markings: Cleavage Lines Collagen fibers arranged in bundles form cleavage (tension) lines Incisions made parallel to cleavage lines heal more readily

21. Copyright © 2010 Pearson Education, Inc. Figure 5.4b (b)

22. Copyright © 2010 Pearson Education, Inc. Skin Color Three pigments contribute to skin color: 1.Melanin Yellow to reddish-brown to black, responsible for dark skin colors Produced in melanocytes; migrates to keratinocytes where it forms “pigment shields” for nuclei Freckles and pigmented moles Local accumulations of melanin

23. Copyright © 2010 Pearson Education, Inc. Skin Color 2.Carotene Yellow to orange, most obvious in the palms and soles 3.Hemoglobin Responsible for the pinkish hue of skin

24. Copyright © 2010 Pearson Education, Inc. Appendages of the Skin Derivatives of the epidermis Sweat glands Oil glands Hairs and hair follicles Nails

25. Copyright © 2010 Pearson Education, Inc. Sweat Glands Two main types of sweat (sudoriferous) glands 1.Eccrine (merocrine) sweat glands—abundant on palms, soles, and forehead Sweat: 99% water, NaCl, vitamin C, antibodies, dermcidin, metabolic wastes Ducts connect to pores Function in thermoregulation

26. Copyright © 2010 Pearson Education, Inc. Figure 5.5b (b) Photomicrograph of a sectioned eccrine gland (220x) Secretory cells Dermal connective tissue Duct Sebaceous gland Sweat pore Eccrine gland

27. Copyright © 2010 Pearson Education, Inc. Sweat Glands 2.Apocrine sweat glands—confined to axillary and anogenital areas Sebum: sweat + fatty substances and proteins Ducts connect to hair follicles Functional from puberty onward (as sexual scent glands?) Specialized apocrine glands Ceruminous glands—in external ear canal; secrete cerumen Mammary glands

28. Copyright © 2010 Pearson Education, Inc. Sebaceous (Oil) Glands Widely distributed Most develop from hair follicles Become active at puberty Sebum Oily holocrine secretion Bactericidal Softens hair and skin

29. Copyright © 2010 Pearson Education, Inc. Figure 5.5a (a) Photomicrograph of a sectioned sebaceous gland (220x) Sebaceous gland duct Hair in hair follicle Secretory cells Dermal connective tissue Sebaceous gland Sweat pore Eccrine gland

30. Copyright © 2010 Pearson Education, Inc. Hair Functions Alerting the body to presence of insects on the skin Guarding the scalp against physical trauma, heat loss, and sunlight Distribution Entire surface except palms, soles, lips, nipples, and portions of external genitalia

31. Copyright © 2010 Pearson Education, Inc. Hair Consists of dead keratinized cells Contains hard keratin; more durable than soft keratin of skin Hair pigments: melanins (yellow, rust brown, black) Gray/white hair: decreased melanin production, increased air bubbles in shaft

32. Copyright © 2010 Pearson Education, Inc. Figure 5.6a Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb (a) Diagram of a cross section of a hair within its follicle Connective tissue root sheath Glassy membrane External epithelial root sheath Internal epithelial root sheath Follicle wall Cuticle Cortex Medulla Hair

33. Copyright © 2010 Pearson Education, Inc. (b) Photomicrograph of a cross section of a hair and hair follicle (250x) Connective tissue root sheath Follicle wall Cuticle Glassy membrane Cortex Medulla Internal epithelial root sheath External epithelial root sheath Hair Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb Figure 5.6b

34. Copyright © 2010 Pearson Education, Inc. Hair Follicle Extends from the epidermal surface into dermis Two-layered wall: outer connective tissue root sheath, inner epithelial root sheath Hair bulb: expanded deep end

35. Copyright © 2010 Pearson Education, Inc. Hair Follicle Hair follicle receptor (root hair plexus) Sensory nerve endings around each hair bulb Stimulated by bending a hair Arrector pili Smooth muscle attached to follicle Responsible for “goose bumps”

36. Copyright © 2010 Pearson Education, Inc. Figure 5.6c Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb (c)Diagram of a longitudinal view of the expanded hair bulb of the follicle, which encloses the matrix Internal epithelial root sheath External epithelial root sheath Connective tissue root sheath Follicle wall Hair matrix Melanocyte Hair papilla Subcutaneous adipose tissue Medulla Cortex Cuticle Glassy membrane Hair root

37. Copyright © 2010 Pearson Education, Inc. (d) Photomicrograph of longitudinal view of the hair bulb in the follicle (160x) Follicle wall Hair matrix Hair papilla Subcutaneous adipose tissue Hair root Connective tissue root sheath Glassy membrane External epithelial root sheath Internal epithelial root sheath Cuticle Cortex Medulla Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb Figure 5.6d

38. Copyright © 2010 Pearson Education, Inc. Types of Hair Vellus—pale, fine body hair of children and adult females Terminal—coarse, long hair of eyebrows, scalp, axillary, and pubic regions (and face and neck of males)

39. Copyright © 2010 Pearson Education, Inc. Types of Hair Hair Growth Growth phase (weeks to years) followed by regressive stage and resting phase (1–3 months) Growth phase varies (6–10 years in scalp, 3–4 months in eyebrows)

40. Copyright © 2010 Pearson Education, Inc. Hair Thinning and Baldness Alopecia—hair thinning in both sexes after age 40 True (frank) baldness Genetically determined and sex-influenced condition Male pattern baldness is caused by follicular response to DHT

41. Copyright © 2010 Pearson Education, Inc. Structure of a Nail Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes

42. Copyright © 2010 Pearson Education, Inc. Figure 5.7 Lateral nail fold Lunule Nail matrix Root of nail Proximal nail fold Hyponychium Nail bed Phalanx (bone of fingertip) Eponychium (cuticle) Body of nail Free edge of nail (a) (b)

43. Copyright © 2010 Pearson Education, Inc. Functions of the Integumentary System 1.Protection—three types of barriers Chemical Low pH secretions (acid mantle) and defensins retard bacterial activity

44. Copyright © 2010 Pearson Education, Inc. Functions of the Integumentary System Physical/mechanical barriers Keratin and glycolipids block most water and water- soluble substances Limited penetration of skin by lipid-soluble substances, plant oleoresins (e.g., poison ivy), organic solvents, salts of heavy metals, some drugs Biological barriers Dendritic cells, macrophages, and DNA

45. Copyright © 2010 Pearson Education, Inc. Functions of the Integumentary System 2.Body temperature regulation ~500 ml/day of routine insensible perspiration (at normal body temperature) At elevated temperature, dilation of dermal vessels and increased sweat gland activity (sensible perspirations) cool the body 3.Cutaneous sensations Temperature, touch, and pain

46. Copyright © 2010 Pearson Education, Inc. Functions of the Integumentary System 4.Metabolic functions Synthesis of vitamin D precursor and collagenase Chemical conversion of carcinogens and some hormones 5.Blood reservoir—up to 5% of body’s blood volume 6.Excretion—nitrogenous wastes and salt in sweat

47. Copyright © 2010 Pearson Education, Inc. Phases of Wound Healing 1. Inflammatory phase: blood clot forms to loosely unite wound edges; blood vessels dilate and become more permeable; phagocytes and mesenchyme cells migrate to site of injury 2. Migratory phase: clot becomes scab; epithelial cells migrate beneath scab; fibroblasts synthesize scar tissue; begin repair of damaged blood vessels; granulation tissue fills wound 3. Proliferative phase: extensive growth of epithelium beneath scab; fibroblasts deposit collagen fibers in random patterns; further vessel repair 4. Maturation phase: scab falls off; collagen fibers become organized; fibroblasts decrease in number; blood vessels repaired Skin GraphSkin Graph

48. Copyright © 2010 Pearson Education, Inc. Skin Cancer Most skin tumors are benign (do not metastasize) Risk factors Overexposure to UV radiation Frequent irritation of the skin Some skin lotions contain enzymes in liposomes that can fix damaged DNA

49. Copyright © 2010 Pearson Education, Inc. Skin Cancer Three major types: Basal cell carcinoma Least malignant, most common Squamous cell carcinoma Second most common Melanoma Most dangerous

50. Copyright © 2010 Pearson Education, Inc. Basal Cell Carcinoma Stratum basale cells proliferate and slowly invade dermis and hypodermis Cured by surgical excision in 99% of cases

51. Copyright © 2010 Pearson Education, Inc. Figure 5.8a

52. Copyright © 2010 Pearson Education, Inc. Squamous Cell Carcinoma Involves keratinocytes of stratum spinosum Most common on scalp, ears, lower lip, and hands Good prognosis if treated by radiation therapy or removed surgically

53. Copyright © 2010 Pearson Education, Inc. Figure 5.8b

54. Copyright © 2010 Pearson Education, Inc. Melanoma Involves melanocytes Highly metastatic and resistant to chemotherapy Treated by wide surgical excision accompanied by immunotherapy

55. Copyright © 2010 Pearson Education, Inc. Melanoma Characteristics (ABCD rule) A: Asymmetry; the two sides of the pigmented area do not match B: Border exhibits indentations C: Color is black, brown, tan, and sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil eraser)

56. Copyright © 2010 Pearson Education, Inc. Figure 5.8c

57. Copyright © 2010 Pearson Education, Inc. Burns Heat, electricity, radiation, certain chemicals  Burn (tissue damage, denatured protein, cell death) Immediate threat: Dehydration and electrolyte imbalance, leading to renal shutdown and circulatory shock

58. Copyright © 2010 Pearson Education, Inc. Rule of Nines Used to estimate the volume of fluid loss from burns

59. Copyright © 2010 Pearson Education, Inc. Figure 5.9 Anterior and posterior head and neck, 9% 4 1 / 2 % 4 1 / 2 % Anterior and posterior upper limbs, 18% Anterior and posterior lower limbs, 36% 100% Totals Anterior and posterior trunk, 36% Anterior trunk, 18% 9% (Perineum, 1%) 4 1 / 2 %

60. Copyright © 2010 Pearson Education, Inc. Partial-Thickness Burns First degree Epidermal damage only Localized redness, edema (swelling), and pain Second degree Epidermal and upper dermal damage Blisters appear

61. Copyright © 2010 Pearson Education, Inc. Figure 5.10a (a)Skin bearing partial thickness burn (1st and 2nd degree burns) 1st degree burn 2nd degree burn

62. Copyright © 2010 Pearson Education, Inc. Full-Thickness Burns Third degree Entire thickness of skin damaged Gray-white, cherry red, or black No initial edema or pain (nerve endings destroyed) Skin grafting usually necessary

63. Copyright © 2010 Pearson Education, Inc. Figure 5.10b (b)Skin bearing full thickness burn (3rd degree burn) 3rd degree burn

64. Copyright © 2010 Pearson Education, Inc. Severity of Burns Critical if: >25% of the body has second-degree burns >10% of the body has third-degree burns Face, hands, or feet bear third-degree burns

65. Copyright © 2010 Pearson Education, Inc. Developmental Aspects: Fetal Ectoderm  epidermis Mesoderm  dermis and hypodermis Lanugo coat: covering of delicate hairs in 5th and 6th month Vernix caseosa: sebaceous gland secretion; protects skin of fetus

66. Copyright © 2010 Pearson Education, Inc. Developmental Aspects: Adolescent to Adult Sebaceous gland activity increases Effects of cumulative environmental assaults show after age 30 Scaling and dermatitis become more common

67. Copyright © 2010 Pearson Education, Inc. Developmental Aspects: Old Age Epidermal replacement slows, skin becomes thin, dry, and itchy Subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells