Anatomy and Physiology 101: Unit 5 chapter 6 - The Integumentary System

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Chapter 6 THE INTEGUMENTARY SYSTEMSkin Cutaneous membrane covering the entire bodyLargest organ (22 square feet; 1 – 2 mm thick; 10 lbs)Skin derivativesSweat glandsOil glandsHairsNails
2SKIN FUNCTIONSProtects deeper tissues from:Mechanical damageChemical damageBacterial damageThermal damageUltraviolet radiationDesiccation – drying outAids in heat regulationAids in excretion – 400mL water, salt, urea, carbon dioxideSynthesizes vitamin D – activated by UV light
3FUNCTIONS OF SKIN -- THERMOREGULATIONPerspiration & its evaporation lowers body temperatureflow of blood in the dermis is adjustedExercisein moderate exercise, more blood brought to surface helps lower temperaturewith extreme exercise, blood is shunted to muscles and body temperature risesShivering and constriction of surface vesselsraise internal body temperature as needed
4LAYERS OF THE SKINThe superficial portion of the skin is the epidermisIt is composed of epithelial tissue.The deeper layer of the skin is the dermis It is primarily composed of connective tissue.Deep to the dermis is the subcutaneous layeror hypodermis. (nota part of the skin)It consistsof connective and adipose tissue.
5LAYERS OF SKIN: EPIDERMISStratified squamous epitheliumavascular (contains no blood vessels)4 types of cells5 distinct strata (layers) of cells
6FOUR PRINCIPLE CELLS OF THE EPIDERMISkeratinocytes - 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 - produce the pigment melanin which contributes to skin color and absorbs damaging ultraviolet (UV) lightLangerhans cells - participate in immune responseMerkel cells- contact a sensory structure called a tactile (Merkel) disc and function in the sensation of touch
7LAYERS (STRATA) OF THE EPIDERMISStratum corneum - Constant exposure to friction will cause this layer to increase in depth with the formation of a callus, an abnormal thickening of the epidermis.Stratum lucidum(clear layer)—cells filled with keratin precursor; found in thick skin
8LAYERS (STRATA) OF THE EPIDERMISWhen the basal layer of the epidermis is destroyed, new skin cannot regenerate with a skin graf.Stratum basale(base layer)—single layer of columnar cells; only these cells undergo mitosis, then migrate through the other layers until they are shedStratum spinosum(spiny layer)—cells arranged in 8 to 10 layersStratum granulosum(granular layer)—cells arranged in two to four layers and filled with granules that contain high levels of lysosomal enzymes
9LAYERS OF THE SKIN: DERMISConnective tissue layer deep to the epidermisMuch thicker than the epidermisContains hair follicles, glands, nerves & blood vessels
LAYERS OF THE DERMISPapillary layerDermal papillae extending into the epidermisLoose Areolar Connective tissueReticular layerDense collagen and elastin fiber

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Term
Fall
Professor
TBD
Tags
Skin Cancer Foundation, Stratum lucidum, Stratum Corneum

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