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Tissue: The Living FabricCh.4The Study of Tissues50 trillion cells of 200 different cell types

four broad categories of tissuesepithelial tissueconnective tissuenervous tissuemuscular tissue

organ - structure with discrete boundaries that is composed of two or more tissue types

histology (microscopic anatomy) the study of tissues and how they are arranged into organs5-2Epithelial Tissueconsists of a flat sheet of closely adhering cells

one or more cells thick

upper surface usually exposed to the environment or an internal space in the body

covers body surface

lines body cavities

forms the external and internal linings of many organs

constitutes most glands

extracellular material is so thin it is not visible with a light microscope

epithelia allows no room for blood vessels

lie on a layer of loose connective tissue and depend on its blood vessels for nourishment and waste removal5-3Basement Membranebasement membrane layer between an epithelium and the underlying connective tissue

basement membrane contains:collagenlaminin and fibronectin adhesive glycoproteinsheparin sulfate - large protein-carbohydrate complex

anchors the epithelium to the connective tissue below it

basal surface surface of an epithelial cell that faces the basement membrane

apical surface surface of an epithelial cell that faces away from the basement membrane5-4Simple vs. Stratified EpitheliaSimple epitheliumcontains one layer of cellsnamed by shape of cellsall cells touch the basement membrane5-5 Stratified epithelium contains more than one layer named by shape of apical cells some cells rest on top of others and do not touch basement membraneFigure 5.3Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

SquamousCuboidalColumnarSimpleClasses of epitheliumPseudostratifiedcolumnarStratifiedCell shapesSimple Epitheliafour types of simple epithelia

three named for their cell shapessimple squamous (thin scaly cells)simple cuboidal (square or round cells)simple columnar (tall narrow cells)

fourth type pseudostratified columnarnot all cells reach the free surfaceshorter cells are covered over by taller oneslooks stratifiedevery cell reaches the basement membrane

goblet cells wineglass-shaped mucus secreting cells in simple columnar and pseudostratified epithelia5-65-7single row of thin cellspermits rapid diffusion or transport of substancessecretes serous fluidalveoli, glomeruli, endothelium, and serosaFigure 5.4b,iFigure 5.4a

Squamous epithelial cellsBasement membraneNuclei of smooth muscle(b)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)

Simple Squamous EpitheliumSimple Cuboidal Epitheliumsingle layer of square or round cellsabsorption and secretion, mucus production and movementliver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules5-8Figure 5.5b,iFigure 5.5a

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Lumen of kidney tubuleCuboidal epithelial cellsBasement membrane(b)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a: The McGraw-Hill Companies, Inc./Dennis Strete, photographersingle row tall, narrow cellsoval nuclei in basal half of cellbrush border of microvilli, ciliated in some organs, may possess goblet cellsabsorption and secretion; mucus secretion lining of GI tract, uterus, kidney and uterine tubes5-9Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

ConnectivetissueBasementmembraneNucleiGobletcell(b)ColumnarcellsBrush border(microvilli)Figure 5.6b,iSimple Columnar EpitheliumPseudostratified Epitheliumlooks multilayered; some not reaching free surface; all touch basement membranenuclei at several layerswith cilia and goblet cellssecretes and propels mucus respiratory tract and portions of male urethra5-10Figure 5.7b,iFigure 5.7a

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CiliaBasal cellsGoblet cell(b)Basement membranea: The McGraw-Hill Companies, Inc./Dennis Strete, photographer Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Stratified Epitheliarange from 2 to 20 or more layers of cellssome cells resting directly on othersonly the deepest layer attaches to the basement membranethree stratified epithelia are named for the shapes of their surface cellsstratified squamousstratified cuboidalstratified columnar (rare)fourth typetransitional epitheliummost widespread epithelium in the bodydeepest layers undergo continuous mitosistheir daughter cells push toward the surface and become flatter as they migrate farther upwardfinally die and flake off exfoliation or desquamationtwo kinds of stratified squamous epitheliakeratinized found on skin surface, abrasion resistantnonkeratinized lacks surface layer of dead cells5-11Keratinized Stratified Squamousmultiple cell layers with cells becoming flat and scaly toward surfaceepidermis; palms and soles heavily keratinizedresists abrasion; retards water loss through skin; resists penetration by pathogenic organisms5-12Figure 5.8b,iFigure 5.8a

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Dead squamous cellsLiving epithelial cellsDense irregularconnective tissue(b)Areolar tissueCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a: The McGraw-Hill Companies, Inc./Joe DeGrandis, photographer Nonkeratinized Stratified Squamoussame as keratinized epithelium without the surface layer of dead cellstongue, oral mucosa, esophagus and vaginaresists abrasion and penetration of pathogens5-13Figure 5.9b,iFigure 5.9aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a: Ed Reschke

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Living epithelial cellsConnective tissue(b)Transitional Epitheliummultilayered epithelium surface cells that change from round to flat when stretchedallows for filling of urinary tractureter and bladder5-14Figure 5.11b,iFigure 5.11a

(a)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Connectivetissue(b)BasementmembraneBinucleateepithelial cella: Johnny R. Howze Endocrine and Exocrine Glandsgland cell or organ that secrete substances for use elsewhere in the body or releases them for elimination from the body composed of epithelial tissue in a connective tissue framework and capsule

exocrine glands - maintain their contact with the body surface by way of a ductsweat, mammary and tear glands

endocrine glands - lose their contact with the surface and have no ductshormones secretion of endocrine glands secrete (hormones) directly into bloodthyroid, adrenal and pituitary glands

some organs have both endocrine and exocrine functionliver, gonads, pancreas

unicellular glands found in epithelium that is predominantly nonsecretorycan be endocrine or exocrinemucus-secreting goblet or endocrine cells of stomach and small intestine5-15Exocrine Gland Structureparenchyma the cells that perform the tasks of synthesis and secretiontypically cuboidal or simple columnar epithelium5-16Figure 5.29

DuctAcinusSecretoryvesiclesDuctSecretoryaciniLobulesLobesSeptumCapsuleStroma:(a)(b)Parenchyma

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.DuctSecretory portionCompound acinarCompound tubuloacinarSimple coiled tubularExample: Sweat glandExample: Mammary glandExample: PancreasKeyTypes of Exocrine Glandssimple - unbranched ductcompound - branched ductshape of glandtubular duct and secretory portion have uniform diameteracinar - secretory cells form dilated sac (acinus or alveolus)tubuloacinar - both tubular and acinar portions5-17Figure 5.30Types of Secretionsserous glandsproduce thin, watery secretionsperspiration, milk, tears and digestive juicesmucous glandsproduce glycoprotein, mucin, that absorbs water to form a sticky secretion called mucusgoblet cells unicellular mucous glandsmixed glands contain both cell types and produce a mixture of the two types of secretionscytogenic glands release whole cells, sperm and egg cells5-18Connective Tissueconnective tissue a type of tissue in which cells usually occupy less space than the extracellular material

binds organs to each other

support and protect organs

most cells of connective tissue are not in direct contact with each otherseparated by extracellular material

highly vascular richly supplied with blood vessels

most abundant and widely distributed5-19Functions of Connective Tissuebinding of organs tendons and ligaments

support bones and cartilage

physical protection cranium, ribs, sternum

immune protection white blood cells attack foreign invaders

movement bones provide lever system

storage fat, calcium, phosphorus

heat production metabolism of brown fat in infants

transport - blood5-20Components of Fibrous Connective Tissuecellsfibroblasts produce fibers and ground substancemacrophages phagocytize foreign material and activate immune system when sense foreign matter (antigen)arise from white blood cell - monocytesleukocytes or white blood cellsneutrophils wander in search of and attacking bacterialymphocytes react against bacteria, toxins, and other foreign materialplasma cells synthesize disease fighting antibodiesarise from lymphocytesmast cells found along side of blood vesselssecrete heparin inhibits clottinghistamine that dilates blood vesselsadipocytes store triglycerides (fat molecules)5-21Components of Fibrous Connective Tissuefiberscollagenous fibersmost abundant of the bodys proteins 25%tough, flexible, and resist stretchingtendons, ligaments, and deep layer of the skin are mostly collagenless visible in matrix of cartilage and bone

reticular fibersthin collagen fibersform framework of such organs as spleen and lymph nodes

elastic fibersthinner than collagenous fibersbranch and rejoin each othermade of protein called elastinallows stretch and recoil5-22Components of Fibrous Connective Tissueground substanceusually a gelatinous to rubbery consistency resulting from three classes of large moleculesglycosaminoglycans (GAG)chondroitin sulfate most abundant GAGin blood vessels and boneresponsible for stiffness of cartilageproteoglycanforms thick colloids that creates strong structural bond between cells and extracellular macromolecules holds tissues togetheradhesive glycoproteins bind components of tissues together5-23Types of Fibrous Connective Tissueloose connective tissuemuch gel-like ground substance between cellstypesareolarreticulardense connective tissuefibers fill spaces between cellstypes vary in fiber orientationdense regular connective tissuedense irregular connective tissue5-24Figure 5.13Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Tendons The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/Don Kincaid, dissections5-25Dense Regular Connective Tissuedensely, packed, parallel collagen fiberscompressed fibroblast nuclei tendons attach muscles to bones and ligaments hold bones togetherFigure 5.16b,iFigure 5.16aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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(b)Fibroblast nucleiGround substanceCollagen fibersa: The McGraw-Hill Companies, Inc./Dennis Strete, photographer 5-26Dense Irregular Connective Tissuedensely packed, randomly arranged, collagen fibers and few visible cellswithstands unpredictable stressesdeeper layer of skin; capsules around organsFigure 5.17b,iFigure 5.17aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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(b)FibroblastnucleiGlandductsBundles ofcollagen fibersGroundsubstancea: The McGraw-Hill Companies, Inc./Dennis Strete, photographer 5-27Adipose Tissueempty-looking cells with thin margins; nucleus pressed against cell membraneenergy storage, insulation, cushioningsubcutaneous fat and organ packingbrown fat (hibernating animals) produces heatFigure 5.18b,iFigure 5.18a

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(b)Lipid inadipocyteAdipocytenucleusBloodvessela: The McGraw-Hill Companies, Inc./Dennis Strete, photographerCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.5-28Cartilagesupportive connective tissue with flexible, rubbery matrix

gives shape to ear, tip of nose, and larynx

No blood vesselsdiffusion brings nutrients and removes wastesheals slowly

matrix rich in chondroitin sulfate and contain collagen fibers

types of cartilage vary with fiber typeshyaline cartilage, fibrocartilage and elastic cartilage5-29Hyaline Cartilageclear, glassy microscopic appearance because of unusualfineness of the collagen fibersusually covered by perichondriumarticular cartilage, costal cartilage, trachea, larynx, fetal skeletoneases joint movement, holds airway open, moves vocal cords during speechFigure 5.19a

(a)a: Ed Reschke Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(b)ChondrocytesPerichondriumMatrixLacunaeCellnestFigure 5.19b,i5-30Elastic Cartilagecartilage containing elastic fibers covered with perichondriumprovides flexible, elastic supportexternal ear and epiglottis

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(b)PerichondriumElasticfibersChondrocytesLacunae5-31cartilage containing large, coarse bundles of collagen fibers never has perichondriumresists compression and absorbs shockintervertebral discsFigure 5.21a

Figure 5.21b,iFibrocartilage

(a)a: Dr. Alvin Telser Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(b)CollagenfibersChondrocytes5-32Bone Tissue (compact bone)most compact bone is arranged in cylinders that surround central (haversian or osteonic) canals osteon central canal and its surrounding lamellaeosteocytes mature bone cells that occupy the lacunaecanaliculi delicate canals that radiate from each lacuna to its neighbors, and allows osteocytes to contact each otherperiosteum tough fibrous connective tissue covering of the bone as a wholeFigure 5.22aFigure 5.22b,iCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(a)a: The McGraw-Hill Companies, Inc./Dennis Strete, photographer

(b)Concentriclamellaeof osteonCentralcanalLacunaeCanaliculiOsteon325-33Bloodfluid connective tissue

transports cells and dissolved matter from place to place

formed elements cells and cell fragmentserythrocytes red blood cells transport O2 and CO2leukocytes white blood cells defense against infection and other diseasesplatelets cell fragments involved in clotting and other mechanismsFigure 5.23b,i

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(b)MonocyteErythrocytesLymphocyteNeutrophilsPlatelets5-34Nervous Tissuenervous tissue specialized for communication by electrical and chemical signals

consists of neurons (nerve cells) detect stimulirespond quicklytransmit coded information rapidly to other cells

neuron partsneurosoma (cell body)houses nucleus and other organellesdendritesmultiple short, branched processesreceive signals from other cellstransmit messages to neurosomaaxon (nerve fiber)sends outgoing signals to other cellscan be more than a meter longFigure 5.24b,i

(b)DendritesNeurosomaAxonNuclei of glial cellsCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.5-35Muscular Tissuemuscular tissue elongated cells that are specialized to contract in response to stimulation

primary job is to exert physical force on other tissues and organs

creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation

important source of body heat

three types of muscle: skeletal, cardiac, and smooth5-36Skeletal Musclelong, threadlike cells muscle fibersmost attach to boneexceptions in tongue, upper esophagus, facial muscles, some sphincter muscles (ringlike or cufflike muscles that open and close body passages)contains multiple nuclei adjacent to plasma membranestriations alternating dark and light bandsvoluntary conscious control over skeletal musclesFigure 5.25aFigure 5.25b,i

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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.StriationsMuscle fiber(b)Nucleia: Ed Reschke5-37Cardiac Musclelimited to the heartmyocytes or cardiocytes are much shorter, branched, and notched at endscontain one centrally located nucleus surrounded by light staining glycogenstriated, and involuntary (not under conscious control)Figure 5.26aFigure 5.26b,i

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)

(b)GlycogenStriationsIntercalated discs Ed Reschke 5-38Smooth MuscleFigure 5.27a

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Muscle cellsNuclei(b)Figure 5.27b,ia: The McGraw-Hill Companies, Inc./Dennis Strete, photographerlacks striations and is involuntaryrelatively short, fusiform cells (thick in middle, tapered at ends)one centrally located nucleusvisceral muscle forms layers of digestive, respiratory, and urinary tract: blood vessels, uterus and other viscerapropels contents through an organ, regulates diameter of blood vessels5-39Tissue Repairregeneration - replacement of dead or damaged cells by the same type of cell as beforerestores normal functionskin injuries and liver regenerate

fibrosis - replacement of damaged cells with scar tissue holds organs togetherdoes not restore normal functionsevere cuts and burns, healing of muscle injuries, scarring of lungs in tuberculosis5-40Wound Healingsevered blood vessels bleed into cut

mast cells and damaged cells release histaminedilates blood vesselsincreases blood flow to area

blood plasma seeps into the wound carrying:antibodiesclotting proteinsblood cellsFigure 5.33 (1)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

1Bleeding into the wound5-41Wound Healingnew capillaries sprout from nearby vessels and grow into wound

deeper portions become infiltrated by capillaries and fibroblastsfibroblasts deposit new collagenbegins 3-4 days after injury and lasts up to 2 weeks

ScabMacrophagesFibroblastsFormation of granulation tissue (fibroblastic phase of repair)Blood capillaryGranulation tissue3Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Figure 5.33 (3)5-42Wound Healingsurface epithelial cells around wound multiply and migrate into wound area beneath scab

epithelium regenerates

scar tissue may or may not show through epithelium

Epidermal regrowthScar tissue (fibrosis)Epithelial regeneration and connective tissue fibrosis (remodeling phase of repair)4Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Figure 5.33 (4)