Anatomy & Physiology: Skin - McGraw Hill PDF

Because learning changes everything. ® Chapter 6 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or...

Because learning changes everything. ® Chapter 6 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. Integumentary System Integumentary system Covers body and consists of skin and accessary tissues (nails, hair, sweat glands, sebaceous glands) Integument skin Cutaneous membrane Barrier to the outside world Visual indicator of our physiology and health Dermatology, study of skin Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 2 6.1 Composition and Functions of the Integument Layers of the integument: Epidermis Stratified squamous epithelium Dermis Deeper layer Primarily dense irregular connective tissue Subcutaneous layer (hypodermis) (SubQ) Deep to dermis Layer of alveolar and CT Not part of integumentary system Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 3  Layers of the Integument Figure 6.1 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4 The Integument Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. The Skin (Drawing): Barbara Cousins. (Photo): Ed Reschke. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6.1a Epidermis 1 Epidermis - epithelium of the integument Keratinized, stratified squamous epithelium Layers (strata) from deep to superficial: 1. Stratum basale 2. Stratum spinosum 3. Stratum granulosum 4. Stratum lucidum (thick skin only) 5. Stratum corneum First three layers composed of living keratinocytes Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7 6.1a Epidermis 2 Stratum basale Deepest epidermal layer Single layer of cuboidal to low columnar cells Three cell types: 1. Keratinocytes 2. Melanocytes 3. Tactile cells Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 8 6.1a Epidermis 3 Stratum basale (continued) Keratinocytes Found in all layers Those in stratum basale are large stem cells Divide to regenerate new cells Synthesize keratin Protein that strengthens epidermis Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9 6.1a Epidermis 4 Stratum basale (continued) Melanocytes Scattered among keratinocytes in stratum basale Produce and store pigment (melanin) in response to ultraviolet light Transfer pigment granules (melanosomes) into keratinocytes Shield nuclear DNA from UV radiation Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10 6.1a Epidermis 5 Stratum basale (continued) Tactile cells Also called Merkel cells Few in number Sensitive to touch When compressed, release chemicals, stimulate sensory nerve endings Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11 6.1a Epidermis 6 Stratum spinosum Several layers of polygonal keratinocytes New cells from stratum basale pushed into this layer Epidermal dendritic cells (Langerhans cells) found in stratum spinosum and granulosum Initiate immune response Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 12 6.1a Epidermis 7 Stratum granulosum 3 to 5 layers of keratinocytes Keratinocytes begin keratinization Keratinocytes fill with keratin Nucleus and organelles to disintegrate, cells are dead Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13 6.1a Epidermis 8 Stratum lucidum Translucent layer, 2 to 3 cell layers thick Found only on thick skin on palms and soles Cells filled with a translucent protein, eleidin Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 14 6.1a Epidermis 9 Stratum corneum Superficial stratum composed of 20 to 30 layers of dead, interlocking, anucleate (lacking a nucleus), keratinized cells Dry, thickened surface is protective against abrasion and infection Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15  Epidermal Strata (a) ©Ed Reschke/Photolibrary/Getty Images Figure 6.2 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16 Practice Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6.1a Epidermis 10 Variations in the epidermis Thickness, color, and skin markings Thick versus thin skin Thick skin Palms of hands, soles of feet Contains all five layers of epidermal strata Sweat glands but no hair follicles or sebaceous glands Thin skin Covers most of body Lacks a stratum lucidum Sweat glands, hair follicles, and sebaceous glands Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18  Thick Skin and Thin Skin (a) ©Carolina Biological Supply Company/Phototake; (b) ©Carolina Biological Supply Company/Medical Images Figure 6.3 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19  Friction Ridges of Thick Skin Figure 6.5 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20 6.1a Epidermis 11 Skin color Normal color from hemoglobin, melanin, carotene Hemoglobin Oxygen-binding protein in red blood cells Bright red color upon binding oxygen Melanin Dark pigment produced in melanocytes, transferred to keratinocytes Eumelanin – brown, black shades; pheomelanin – lighter shades: tan, yellow, red Amount in skin varies (heredity, UV exposure) Albinism: Melanocytes unable to produce melanin Carotene Yellow-orange pigment acquired from some vegetables Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21  Production of Melanin by Melanocytes (b) ©John Burbidge/Science Source Figure 6.4 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22 Other Pigments (Slide 1 of 2) Beta-carotene can also contribute to skin color Lipofuscin: Accumulates in cells that have ceased mitosis in aging skin, producing brown-yellow age spots Hemosiderin staining: brownish staining from red blood cells breaking down. Often occurs with venous insufficiency. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. Other Pigments (Slide 2 of 2) Hemoglobin: Color changes also occur as a result of changes in blood flow Redder skin color when blood flow to skin increases Cyanosis: Bluish color caused by darkening of hemoglobin when it is oxygen poor Other pigments: From cosmetics, tattoos, bile pigments in jaundice Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? From Epstein O, Perkin GD, Cookson J, de Bono D: Clinical examination, ed 3, St Louis, 2003, Mosby. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. Section 6.1a What did you learn? 1. As you trim your roses, a thorn penetrates your palm through all epidermal strata. What are the layers of the epidermis penetrated, starting from the surface of the skin? 2. Briefly describe the process of keratinization. Where does it occur? Why is it important? 3. How does hemoglobin contribute to skin color? 4. Make a chart that lists the epidermal cells, and list the layers in which each cell type may be found. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32 6.1b Dermis 1 Dermis Deep to epidermis Composed of CT proper Other structures present: Blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings, arrector pili, motile dendritic cells Papillary and reticular layers Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 6.1b Dermis 2 Papillary layer of dermis Superficial region of dermis, deep to epidermis Areolar connective tissue Named for projections of dermis, dermal papillae Interlock with epidermal ridges to increase area of contact between layers Reticular layer of dermis Deeper, major portion of dermis Dense irregular connective tissue Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34  Layers of the Dermis (b) ©Steve Gschmeissner/Science Source; (c) ©Susumu Nishinaga/Science Source Figure 6.6 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35 6.1b Dermis 3 Lines of cleavage and stretch marks Collagen and elastic fibers oriented in parallel bundles at specific locations Bundles function to resist stress during routine movement Orientation indicated by lines of cleavage (tension lines) Incisions parallel to cleavage lines more likely to heal quickly Incisions perpendicular to cleavage lines are more likely to open due to cut elastic fibers If skin stretched beyond its capabilities Some collagen fibers torn, results in stretch marks (striae) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36  Lines of Cleavage Figure 6.7 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 Clinical View: Tattoos Permanent images produced on integument Dye injected into dermis Permanent part of dermis layer Usually impossible to completely remove a tattoo Lasers used to break down pigments Newer inks are available that allow for removal Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 38 6.1c Subcutaneous Layer Subcutaneous layer (hypodermis, superficial fascia) Not part of integument Areolar and adipose CT Functions: Protection, energy storage, and insulation Common drug injection site Extensive vascular network promotes rapid absorption Thickness/distribution influenced by sex hormones Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39 Sections 6.1b-c What did you learn? 5. Compare and contrast the papillary versus reticular layer of the dermis, with respect to their tissue type and the structures they contain. 6. What is indicated by the lines of cleavage in the skin, and why is this medically important? 7. What types of tissue form the subcutaneous layer? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40 6.1d Functions of the Integument 1 Protection from the external environment Protects body from injury, harmful substances, microbes, extreme temperatures, and UV radiation Prevention of water loss/gain Epidermis is water resistant, not waterproof Water lost by sweat and transpiration Vitamin D synthesis Formation of vitamin D3, a precursor to calcitriol Calcitriol increases absorption of calcium and phosphate from diet; regulates blood calcium levels Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 41 6.1d Functions of the Integument 2 Secretion Waste products secreted onto skin surface during sweating Absorption Skin absorbs some chemicals/drugs but blocks others Selectively permeable Suitable for transdermal administration of some drugs Immune function Dendritic cells in epidermis and dermis capable of initiating immune response Temperature regulation Dermal blood vessels capable of vasoconstriction to conserve heat or vasodilation to release heat Sensory reception Receptors detect stimuli (e.g., touch, pressure) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 42 Section 6.1d What did you learn? 8. How does the skin produce vitamin D? 9. Is the skin entirely waterproof? Explain. 10. What are some ways the skin can dissipate excess heat? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 43 6.2a Nails 1 Structure of nails Scalelike modifications of stratum corneum Dorsal edges of fingers and toes Protect distal tips of digits Assist in grasping objects Distal whitish free edge (no underlying capillaries) Pinkish nail body (underlying capillaries) Nail root (part embedded in skin) These three constitute nail plate Nail bed Layer of living epidermis covered by nail body Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 44 6.2a Nails 2 Structure of nails (continued) Nail matrix Actively growing part of nail at proximal end of nail body Lunula Whitish semilunar area on proximal end of nail body Nail folds Folds of skin overlapping nail Eponychium (cuticle) Narrow band of epidermis from margin of nail wall onto nail body Hyponychium Thickened stratum corneum over which free nail edge projects Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 45  Structure of a Fingernail Figure 6.9 ©John Radcliffe Hospital/Science Source Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 46 Clinical View: Nail Disorders Nails are indicative of overall health Brittle nails are prone to vertical splitting and separation of nail plate layers Ingrown nails with edge of nail digging into skin Onychomycosis is a fungal infection Yellow nail syndrome occurs when growth and thickening slows Spoon nails outer surface of nail is concave Beau’s lines indicate temporary interference with nail growth Vertical ridging common and usually harmless Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 47 6.2b Hair 1 Hair found almost everywhere on the body Keratinized cells form slender filament Grows from hair follicles Three types of hair Lanugo: fine, unpigmented, downy hair Appears in last trimester Vellus: fine hair Primary human hair Found on upper and lower limbs Terminal hair: coarser, pigmented, longer On scalp, eyebrows, and eyelashes, men’s beards During puberty, replaces vellus hair in axillary and pubic regions Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 48 6.2b Hair 2 Hair structure and follicles 3 zones along length of a hair Hair bulb Swelling at base where hair originates in dermis Surrounds hair papilla, composed of CT Only region containing living epithelial cells Root Zone of hair from bulb to skin surface Shaft Portion of hair beyond skin surface Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 49 6.2b Hair 3 Hair components Hair matrix Structure at base of the hair bulb Epithelial cells divide here Produce new cells, gradually pushed toward surface Medulla Remnant of matrix Flexible, soft keratin Cortex Flattened cells closer to outer hair surface Relatively hard Cuticle Single cell layer around cortex Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 50 6.2b Hair 4 Hair components (continued) Hair follicle Oblique tube surrounding hair root Extends into dermis and sometimes subcutaneous layer Outer connective tissue root sheath originating in dermis Inner epithelial tissue root sheath originating from epidermis Arrector pili Thin ribbons of smooth muscle Extend from hair follicle to dermal papillae Elevates hair with contraction, “goosebumps” Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 51  Hair (top b, bottom b) ©McGraw-Hill Education/Al Telser; (c) ©SPL/Science Source Figure 6.10 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 52 6.2b Hair 5 Functions include: Protection On head, from sunburn and injury Respiratory system and ears – hair traps particles, debris Heat retention Sensory reception Root hair plexuses detect light touch Visual identification Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 53 6.2b Hair 6 Hair color Synthesis of melanin in matrix adjacent to hair papillae Lightens with age as pigment production decreases Gray hair results from gradual reduction in melanin White hair occurs due to complete stoppage of melanin production Hair growth and replacement Three phases of hair growth cycle 1. Anagen—active phase of growth 2. Catagen—brief regression period where cell division stops 3. Telogen—resting phase, period when hair is usually shed Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 54 6.2b Hair 7 Hair growth and replacement (continued) Hair loss normally 10 to 100 hairs per day Alopecia areata Autoimmune disorder where follicles are attacked Spots of baldness on scalp and body Diffuse hair loss Hair shed from all parts of scalp Due to hormones, drugs, iron deficiency Male pattern baldness Loss of hair first from only crown region of scalp Genetic and hormonal factors Hirsutism Excessive hairiness Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 55 6.2c Exocrine Glands of the Skin 1 Sweat glands and sebaceous glands Sweat glands include two types Merocrine Apocrine Both types have a coiled, secretory portion with myoepithelial cells that aid in secretion process Both types contain a sweat gland duct Sweat gland duct opens to sweat pore Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 56 6.2c Exocrine Glands of the Skin 2 Merocrine (eccrine) sweat glands Most numerous and widely distributed Simple, coiled tubular glands Discharge secretions onto skin surface Produce secretion by exocytosis Secrete sweat Composed of 99% water and 1% other chemicals Includes: electrolytes, metabolites, and waste products Major role in thermoregulation Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 57 6.2c Exocrine Glands of the Skin 3 Apocrine sweat glands Coiled, tubular glands Discharge secretions into hair follicles located axillae, around nipples, in pubic and anal region Produce secretion by exocytosis Produce viscous cloudy secretions Contain proteins and lipids Produce odor when acted on by bacteria Start producing secretions during puberty Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 58 6.2c Exocrine Glands of the Skin 4 Sebaceous glands Holocrine glands Produce oily secretion, sebum Lubricant for skin and hair Bactericidal Discharges into a hair follicle Secretion stimulated by hormones, especially male sex hormones Activated during puberty Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 59 6.2c Exocrine Glands of the Skin 5 Other integumentary glands Ceruminous glands Modified apocrine sweat glands Located only in external ear canal Secretions of waterproof earwax, cerumen Traps foreign material Lubricates acoustic meatus and eardrum Mammary glands Modified apocrine sweat glands of breast Only function in pregnant and lactating females Produce breast milk Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 60  Exocrine Glands of the Skin Figure 6.11a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 61 Clinical View: Acne and Acne Treatments Acne Plugged sebaceous ducts Typically begins during puberty Increased activity gland secretions may block pores Treatments Benzoyl peroxide, salicylic acid, antibiotics, vitamin A–like compounds, systemic retinoids May lead to scarring if untreated Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 62 Section 6.2 What did you learn? 11. Why is the nail body pinkish, while the free edge of the nail is white? 12. What are the three zones of a hair? 13. How does hair function in protection and heat retention? 14. How do apocrine sweat glands differ from merocrine sweat glands in terms of their location, secretions, and function? 15. What do sebaceous glands secrete, and where is this material secreted? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 63 6.3 Repair and Regeneration of the Integumentary System 1 Tissue is repaired in one of two ways: regeneration or fibrosis Regeneration Replacement of damaged or dead cells with same cell type Restores organ function Fibrosis Gap filled with scar tissue Collagen produced by fibroblasts Functional activities not restored Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 64 6.3 Repair and Regeneration of the Integumentary System 2 Stages of wound healing: 1) Cut blood vessels bleed into wound 2) Blood clot forms and leukocytes clean wound Clot is a temporary barrier for pathogens 3) Blood vessels re-grow and granulation tissue forms Vascular CT initially forms in wound 4) Epithelium regenerates and CT fibrosis occurs Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 65  Stages in Wound Healing Figure 6.12 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 66 Clinical View: Psoriasis Chronic autoimmune skin disease Keratinocytes attacked by T-lymphocytes Causes rapid overgrowth of new skin cells Patches of whitish, scaly skin on epidermal surface Symptoms: severe itching, pain, skin cracking Treatments Corticosteroids, UV light therapy, medications that interfere with skin cell production Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 67 Clinical View: Burns 1 Major cause of accidental death Caused by heat, radiation, chemicals, sunlight, electrical shock Threat to life from fluid loss, infection, effects of burned tissue First degree burns Involve only epidermis Slight redness and pain Immerse burned area in cool water Second degree burns Involve epidermis and part of dermis Skin blistered and painful Slight scarring Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 68 Clinical View: Burns 2 Third-degree burns Involve epidermis, dermis, and subcutaneous layer Require hospitalization Treatment for dehydration and infection Require additional caloric intake Severe scarring May need debridement and skin graft Burn severity can be measured by rule of nines Estimates surface area of burns Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 69 Clinical View: Burns 3 Treatments for burns Manage fluid loss Manage pain Remove dead tissue Control infection Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 70 Section 6.3 What did you learn? 16. What is granulation tissue, and when does it appear during wound healing of the skin? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 71 6.4a Development of the Integument and Its Derivatives 1 Development around week 7 Ectoderm forms a layer of squamous epithelium Becomes periderm and basal layer Basal layer forms all epidermal layers By week 21 Formation of stratum corneum and friction ridges Periderm eventually sloughed off Mixes with sebum to produce coating on fetus skin, vernix caseosa Development around week 11 Dermis is derived from mesoderm Mesoderm becomes mesenchyme Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 72 6.4a Development of the Integument and Its Derivatives 2 By week 32 Fingernails/toenails form Between weeks 9 and 12 Hair follicles appear Pockets of cells, hair buds By week 20 Sweat and sebaceous glands appear on palms/soles; later in other regions Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 73 6.4b Aging of the Integument 1 Skin changes with aging Reduced number and activity of stem cells Skin repair processes slows Thin skin less likely to protect from trauma Fewer collagen fibers Elastic fibers lose elasticity Crease lines form (wrinkles) Immune response decreased due to fewer dendritic cells Hair follicles produce thinner hair or none at all Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 74 6.4b Aging of the Integument 2 Skin changes with aging (continued) Smoking and chronic overexposure to UV radiation Damage DNA in epidermal cells Accelerates aging Predominant factor in promotion of skin cancer Skin cancer Most common type of cancer Typically on head and neck Fair-skinned individuals at highest risk Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 75 Clinical View: Botox and Wrinkles Botox is a treatment for wrinkles caused by facial muscle expression Clostridium botulinum toxin, botulinum toxin Type A Blocks nerve impulses to facial expression muscles Decreases or eliminates wrinkles Botox injected into specific facial muscles Temporary effect only Muscles regain function and procedure must be repeated Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 76 Section 6.4 What did you learn? 17. What two primary germ layers form the integument? 18. How do UV rays contribute to skin aging? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 77  End of Main Content Because learning changes everything. ® www.mheducation.com Copyright 2022 © McGraw Hill LLC. 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