Glandular EpitheliumGland: a single cell or a mass of epithelial cells adapted for secretionderived from epithelial cells that sank below the surface during developmentEndocrine glands are ductless.They secrete their products into ducts that empty at the surface of covering and lining epithelium or directly onto a free surface . Glandular EpitheliumExocrine glandscells that secrete---sweat, ear wax, saliva, digestive enzymes onto free surface of epithelial layerconnected to the surface by tubes ducts! unicellular glandsor multicellular glandsEndocrine glands secrete hormones into the bloodstreamhormones help maintain homeostasis Mechanisms for Glandular SecretionMerocrine Glands:Salivary glandsSudoriferous sweat glands of the skinApocrine Glands:Lactiferous tissue of the Mammary glandsApocrine sweat glandsHolocrine Glands:Sebaceous (oil) glandsof the skin Introduction to the Integumentary SystemThe 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.# large organ composed of all $ tissue types%% s&uare feet '-% mm thick(eight ') lbs. TYPES OF SKINThin skin covers all parts of the body except for the palms and palmar surfaces of the digits and toes.lacks epidermal ridgeshas a sparser distribution of sensory receptors than thick skin.Thick skin ).* to $.+ mm!covers the palms, palmar surfaces of the digits, and solesfeatures a stratum lucidum and thick epidermal ridgeslacks hair follicles, arrector pili muscles, and sebaceous glands, and has more sweat glands than thin skin. FUNCTIONS OF SKINThermoregulation,erspiration - its evaporation lowers body temperatureflow of blood in the dermis is ad.ustedShivering and constriction of surface vesselsraise internal body temperature as neededExercisein moderate exercise, more blood brought to surface helps lower temperaturewith extreme exercise, blood is shunted to muscles and body temperature rises FUNCTIONS OF SKINblood reservoir extensive network of blood vesselsprotection - physical, chemical and biological barrierstight cell .unctions prevent bacterial invasionlipids released retard evaporationpigment protects somewhat against /0 light1angerhans cells alert immune systemcutaneous sensations touch, pressure, vibration, tickle, heat, cold, and pain arise in the skin FUNCTIONS OF SKINSynthesis of Vitamin D activation of a precursor molecule in the skin by /0 lightenzymes in the liver and kidneys modify the activated molecule to produce calcitriol, the most active form of vitamin 2.necessary vitamin for absorption of calcium from food in the gastrointestinal tractexcretion$)) m1 of water3day, small amounts salt, 45%, ammonia and urea Introduction to the Integumentary System Integumentary SystemCutaneous membrane,rotects tissues from physical trauma, biological pathogens, and chemical trauma,rovides sensationsccessory Structures,rovides sensations,roduces secretions,rotects epidermal surfaces Cutaneous MembraneEpidermis:4ontrols skin permeability,revents entry of biological pathogens6ynthesizes vitamin 2Dermis:7ourishes and supports epidermis8estricts spread of pathogens6tores lipids#ttaches skin to underlying tissue6ensory receptors provide sensations9lood vessels assist in thermoregulation Accessory Structures!air "ollicles:,roduce hair that protects underlying skin,rovide sensations#ails:,rotect and support the tips of fingers and toesExocrine Glands:#ssist in thermoregulation:xcrete wastes1ubricate epidermis and hair,roduce pheromones for chemical communication Specific Layer of the SkinEpidermis: 4omposed of keratinized stratified s&uamous epitheliumDermis: ,apillary region composed of areolar tissue 8eticular region composed of dense irregular connective tissue!ypodermis: 4omposed of areolar tissue with abundant adipocytes Specific Layers of the EpidermisStratum $asale:;itotic layer, continuouslyreplaces epidermal cells, turnover rate between %+ to +) daysStratum Spinosum:4ells are pushed upward and flatten out6tratum eratin Specific Layer of the EpidermisStratum %ucidum:5bserved only in non-hairy or thick skin. 6everal layers of dead cells with indistinct boundariesStratum Corneum:4omposed of %+ or more layers of dead s&uamous cells still .oined by desmosomes.:ventually desmosomes break and cells flake off in a process called des&uamation Specialized Cells of the Epidermis&eratinocytes:;ost common cells of the epidermis. ,rovides protection and waterproofing sealant'elanocytes:,roduces and transfer the protein melanin to >eratinocytes.;elanin is a brown3black pigment that absorbs /0-light. Specialized Cells of the Epidermis%angerhans cells:#rise from red bone marrow and migrate to the epidermis.They participate in immune responses against bacteria and viruses.:asily damaged by /0'erkel Cells:?ound in the 6tratum 9asale, they contactthe flattened process of sensory neuron.They respond to touch sensations 6kin 4olor ,igments'elanin produced in epidermis by melanocytes melanocytes convert tyrosine to melanin /0 in sunlight increases melanin productionsame number of melanocytes in everyone, but differing amounts of pigment producedresults vary from yellow to tan to black color 4linical observations freckles or liver spots @ melanocytes in a patchalbinism @ inherited lack of tyrosinaseA no pigmentvitiligo @ autoimmune loss of melanocytes in areas of the skin produces white patches The wide variety of colors in skin is due to three pigments - melanin, carotene, and hemoglobin in blood in capillaries! - in the dermis. 6kin 4olor ,igmentsCarotene in dermis=yellow-orange pigment precursor of vitamin #!found in stratum corneum - dermis !emoglobin in dermis=red, oxygen-carrying pigment in blood cellsif other pigments are not present, epidermis is translucent so pinkness will be evident Layers of the DermisDermis(eticular region:consists of dense irregular 4T4ontain most of the accessory 6tructures)* +apillary (egion:4onsist of areolar Tissue,* Dermal +apilla:?ingerlike pro.ections that greatly increase surface area1

!" Accessory Structures of the Dermispocrine s-eat glands:?ound in the #xillae, nipples, labia, and glans penis.9egin to function at puberty and are affected by hormones,roduce odorous thick secretion,ossible pheromone function Sudoriferous .eccrine/S-eat Gland:(idespread B,)))3s&. in.!,roduce thin watery secretion4ontrolled by nervous systemThermoregulation:xcretion of urea#ntibacterial action Sudoriferous Sweat #land Accessory Structures of the DermisSebaceous 01il2 gland: 6ecrete sebum 4oats hair shaft and lubricates the epidermis 6ecreted to hair follicles 7ot association with hair on the labia, glans penis, and lips #ctivity controlled by sex-hormones ;odified in external ear canal to produce cerumen or ear wax ceruminous glands! Accessory Structures of the Dermis'ammary Glands:#natomically related to apocrine sweat glands2evelopment controls by sex hormones and pituitary hormones,roduce milk Accessory Structures of the DermisCeruminous Glands:;odified sweat glands found in the external auditory canal,roduce cerumen or ear waxCelps trap foreign particles from reaching the eardrum Accessory Structures of the Dermis!air:,resent on most skin except palmer surface, and plantar surface