Chapter 5INTRODUCTIONChapter 5 The Integumentary SystemGeneral AnatomySTRUCTURE OF THE SKIN (Figure 5.1)Overview of EpidermisFour Principle Cells of the Epidermis – Figure 5.2Layers of the EpidermisLayers (Strata) of the EpidermisStratum Basale (stratum germinativum)Stratum Spinosum (Figure 5.2a)Stratum GranulosumStratum LucidumStratum CorneumKeratinization and Growth of the EpidermisClinical ApplicationDermis (Figure 5.1)Dermis - Papillary RegionDermis - Reticular RegionDermis -- StructureTattoosBasis of Skin ColorSkin Color PigmentsSlide 24Accessory Structures of SkinHAIRStructure of HairSlide 28Slide 29Hair Related StructuresTypes of hairHair removalHair GrowthHair ColorFunctions of HairGlands of the SkinSebaceous (oil) glandsSudoriferous (sweat) glandsCeruminous GlandsStructure of Nails (Figure 5.7)Nail GrowthTYPES OF SKINFUNCTIONS OF SKIN -- thermoregulationFUNCTIONS OF SKINSlide 45Transdermal Drug AdministrationMAINTAINING HOMEOSTASIS: SKIN WOUND HEALINGEpidermal Wound HealingDeep Wound HealingDeep Wound HealingPhases of Deep Wound HealingSlide 52DEVELOPMENT OF THE INTEGUMENTARY SYSTEMDevelopment of the SkinAge Related Structural ChangesAGING AND THE INTEGUMENTARY SYSTEMPhotodamageDISORDERS: HOMEOSTATIC IMBALANCESSkin CancerBurnsSlide 61Slide 62Types of BurnsSlide 64Pressure SoresSlide 66Principles of Human Anatomy and Physiology, 11e 1Chapter 5The Integumentary SystemLecture OutlinePrinciples of Human Anatomy and Physiology, 11e 2INTRODUCTION•The skin and its accessory structures make up the integumentary system.•The integumentary system functions to guard the body’s physical and biochemical integrity, maintain a constant body temperature, and provide sensory information about the surrounding environment.Principles of Human Anatomy and Physiology, 11e 3Chapter 5The Integumentary System•Skin and its accessory structures–structure–function–growth and repair–development–aging–disordersPrinciples of Human Anatomy and Physiology, 11e 4General Anatomy•A large organ composed of all 4 tissue types•22 square feet •1-2 mm thick•Weight 10 lbs.Principles of Human Anatomy and Physiology, 11e 5STRUCTURE OF THE SKIN (Figure 5.1)•The superficial portion of the skin is the epidermis and is composed of epithelial tissue.•The deeper layer of the skin is the dermis and is primarily composed of connective tissue.•Deep to the dermis is the subcutaneous layer or hypodermis. (not a part of the skin)–It consists of areolar and adipose tissue.–fat storage, an area for blood vessel passage, and an area of pressure-sensing nerve endings.Principles of Human Anatomy and Physiology, 11e 6Overview of Epidermis•Stratified squamous epithelium–avascular (contains no blood vessels)–4 types of cells–5 distinct strata (layers) of cellsPrinciples of Human Anatomy and Physiology, 11e 7Four Principle Cells of the Epidermis – Figure 5.2•keratinocytes (Figure 5.2a)–produce the protein keratin, which helps protect the skin and underlying tissue from heat, microbes, and chemicals, and lamellar granules, which release a waterproof sealant •melanocytes (Figure 5.2b)–produce the pigment melanin which contributes to skin color and absorbs damaging ultraviolet (UV) light•Langerhans cells (Figure 5.2c)–derived from bone marrow–participate in immune response•Merkel cells (Figure 5.2d)–contact a sensory structure called a tactile (Merkel) disc and function in the sensation of touchPrinciples of Human Anatomy and Physiology, 11e 8Layers of the Epidermis•There are four or five layers of the epidermis, depending upon the degree of friction and mechanical pressure applied to the skin. •From deepest to most superficial the layers of the epidermis are (Figures 5.3 a and b).–stratum basale (stratum germinativum)–stratum spinosum–stratum granulosum–stratum lucidum (only in palms and soles)–stratum corneumPrinciples of Human Anatomy and Physiology, 11e 9Layers (Strata) of the Epidermis•Stratum corneum•Stratum lucidum•Stratum granulosum•Stratum spinosum•Stratum basalePrinciples of Human Anatomy and Physiology, 11e 10Stratum Basale (stratum germinativum)•Deepest single layer of epidermis –merkel cells, melanocytes, keratinocytes & stem cells that divide repeatedly–keratinocytes have a cytoskeleton of tonofilaments –Cells attached to each other & to basement membrane by desmosomes & hemi-desmosomes•When the germinal portion of the epidermis is destroyed, new skin cannot regenerate with a skin graft.Principles of Human Anatomy and Physiology, 11e 11Stratum Spinosum (Figure 5.2a)•provides strength and flexibility to the skin –8 to 10 cell layers are held together by desmosomes.–During slide preparation, cells shrink and appear spiny (where attached to other cells by desmosomes.)•Melanin is taken in by keratinocytes (by phagocytosis) from nearby melanocytes.Principles of Human Anatomy and Physiology, 11e 12Stratum Granulosum•transition between the deeper, metabolically active strata and the dead cells of the more superficial strata•3-5 layers of flat dying cells that show nuclear degeneration–example of apoptosis•Contain lamellar granules that release lipid that repels water•Contain dark-staining keratohyalin granules–keratohyalin converts tonofilaments into keratinPrinciples of Human Anatomy and Physiology, 11e 13Stratum Lucidum •present only in the fingers tips, palms of the hands, and soles of the feet.•Three to five layers of clear, flat, dead cells•Contains precursor of keratinPrinciples of Human Anatomy and Physiology, 11e 14Stratum Corneum•25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids–continuously shed•Barrier to light, heat, water, chemicals & bacteria•Lamellar granules in this layer make it water-repellent.•Constant exposure to friction will cause this layer to increase in depth with the formation of a callus, an abnormal thickening of the epidermis.Principles of Human Anatomy and Physiology, 11e 15Keratinization and Growth of the Epidermis•Stem cells divide to produce keratinocytes•As keratinocytes are pushed up towards the surface, they fill with keratin–Keratinization is replacement of cell contents with the protein keratin; occurs as cells move to the skin surface over 2-4 weeks.•Epidermal growth factor (EGF) and other hormone-like proteins play a role in epidermal growth.•Table 5.1 presents a summary of the features of the epidermal