Chapter 5Lecture OutlineCopyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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5-*HistologyStudy of TissuesEpithelial TissueConnective TissueNervous and Muscular Tissue Intercellular Junctions, Glands and MembranesTissue Growth, Development, Death and Repair

5-*The 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 organs

5-*The Primary Tissue Classestissue a group of similar cells and cell products that arise from the same region of the embryo and work together to perform a specific structural or physiological role in an organ.

four primary tissues differ from one another in the:types and functions of their cellsthe characteristics of the matrix (extracellular material)the relative amount of space occupied by cells versus matrix

matrix (extracellular material) is composed of :fibrous proteinsa clear gel known as ground substance , tissue fluid, extracellular fluid (ECF), interstitial fluid, or tissue gel

5-*Embryonic Tissueshuman development begins as single cell the fertilized eggdivides to produce scores of identical, smaller cellsfirst tissues appear when these cells start to organize themselves into layersfirst two, and then three strata

3 primary germ layersectoderm (outer) gives rise to epidermis and nervous systemendoderm (inner) gives rise to mucous membrane lining digestive and respiratory tracts, digestive glands, and among other thingsmesoderm (middle) becomes gelatinous tissue - mesenchymewispy collagen fibers and fibroblasts in gel matrixgives rise to muscle, bone, blood

5-*Interpreting Tissue Sectionspreparation of histological specimensfixative prevents decay (formalin)histological sections tissue is sliced into thin sections one or two cells thickstains tissue is mounted on slides and artificially colored with histological stainstains bind to different cellular components

Sectioning reduces three-dimensional structure to two-dimensional slice

5-*Sectioning Solid Objectssectioning a cell with a centrally located nucleus

some slices miss the cell nucleus

in some the nucleus is smaller

Figure 5.1aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)

5-*Sectioning Hollow Structurescross section of blood vessel, gut, or other tubular organ.

longitudinal section of a sweat gland. notice what a single slice could look like.

Figure 5.1b,c(b)(c)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Types of Tissue Sectionslongitudinal section (l.s.)tissue cut along long direction of organ

cross section (c.s. or x.s.) or transverse section (t.s.)tissue cut perpendicular to length of organ

oblique sectiontissue cut at angle between cross and longitudinal section

Figure 5.2Longitudinal sectionsCross sectionsOblique sectionsCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Nonsectioned PreparationSmear tissue is rubbed or spread across the slidespinal cord or blood

Spread cobwebby tissue is laid out on a slideareolar tissue

5-*Epithelial 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 removal

5-*Basement 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 membrane

5-*Simple vs. Stratified EpitheliaSimple epitheliumcontains one layer of cellsnamed by shape of cellsall cells touch the basement membrane

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 shapes

Simple 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 epithelia

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5-*single row of thin cellspermits rapid diffusion or transport of substancessecretes serous fluidalveoli, glomeruli, endothelium, and serosa

Figure 5.4b,iFigure 5.4aSquamous epithelial cellsBasement membraneNuclei of smooth muscle(b)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a: The McGraw-Hill Companies, Inc./Dennis Strete, photographer(a)Simple Squamous Epithelium

5-*Simple Cuboidal Epitheliumsingle layer of square or round cellsabsorption and secretion, mucus production and movementliver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules

Figure 5.5b,iFigure 5.5a(a)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, photographer

5-*single 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 tubes

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.ConnectivetissueBasementmembraneNucleiGobletcell(b)ColumnarcellsBrush border(microvilli)Figure 5.6b,iSimple Columnar Epithelium

5-*Pseudostratified 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 urethra

Figure 5.7b,iFigure 5.7a(a)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 cells

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5-*Keratinized 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 organisms

Figure 5.8b,iFigure 5.8a(a)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

5-*Nonkeratinized Stratified Squamoussame as keratinized epithelium without the surface layer of dead cellstongue, oral mucosa, esophagus and vaginaresists abrasion and penetration of pathogens

Figure 5.9b,iFigure 5.9aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a: Ed Reschke(a)Living epithelial cellsConnective tissue(b)

5-*Stratified Cuboidal Epitheliumtwo or more cell layers; surface cells square or roundsecretes sweat; sperm production and produces ovarian hormonessweat gland ducts; ovarian follicles and seminiferoustubules

Figure 5.10aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)EpitheliumConnective tissueCuboidal cells(b)Figure 5.10b,ia: The McGraw-Hill Companies, Inc./Dennis Strete, photographer

5-*Transitional Epitheliummultilayered epithelium surface cells that change from round to flat when stretchedallows for filling of urinary tractureter and bladder

Figure 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

5-*Connective 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, widely distributed, and histologically variable of the primary tissues

5-*Functions 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 - blood

5-*Components 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-*Components 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 fibers coated with glycoproteinform framework of such organs as spleen and lymph nodes

elastic fibersthinner than collagenous fibersbranch and rejoin each othermade of protein called elastinallows stretch and recoilyellow fibers fresh elastic fibers

5-*Components of Fibrous Connective Tissueground substanceusually a gelatinous to rubbery consistency resulting from three classes of large moleculesglycosaminoglycans (GAG)long polysaccharide composed of unusual disaccharides called amino sugars and uronic acidplay important role of regulating water and electrolyte balance in the tissueschondroitin sulfate most abundant GAGin blood vessels and boneresponsible for stiffness of cartilagehyaluronic acid viscous, slippery substance that forms an effective lubricant in joints and constitutes much of the vitreous body of the eyeballproteoglycangigantic molecule shaped like a test-tube brushforms thick colloids that creates strong structural bond between cells and extracellular macromolecules holds tissues togetheradhesive glycoproteins bind components of tissues together

5-*Types 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 tissue

Figure 5.13Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Tendons The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/Don Kincaid, dissections

5-*Areolar Tissueloosely organized fibers, abundant blood vessels, and a lot of seemingly empty space

possess all six cell types

fibers run in random directionsmostly collagenous, but elastic and reticular also present

found in tissue sections from almost every part of the bodysurrounds blood vessels and nervesnearly every epithelium rests on a layer of areolar tissueblood vessels provide nutrition to epithelium and waste removalready supply of infection fighting leukocytes that move about freely in areolar tissue

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5-*Areolar Tissueloosely organized fibers, abundant blood vessels, and a lot of seemingly empty spaceunderlies all epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels

Figure 5.14a(a)Figure 5.14b,ia: The McGraw-Hill Companies, Inc./Dennis Strete, photographer Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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(b)ReticularfibersLeukocytes5-*Reticular Tissuemesh of reticular fibers and fibroblastsforms supportive stroma (framework) for lymphatic organsfound in lymph nodes, spleen, thymus and bone marrow

Figure 5.15aa: The McGraw-Hill Companies, Inc./Al Telser, photographer(a)Figure 5.15b,iCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Dense Regular Connective Tissuedensely, packed, parallel collagen fiberscompressed fibroblast nuclei tendons attach muscles to bones and ligaments hold bones together

Figure 5.16b,iFigure 5.16aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)(b)Fibroblast nucleiGround substanceCollagen fibersa: The McGraw-Hill Companies, Inc./Dennis Strete, photographer

5-*Dense Irregular Connective Tissuedensely packed, randomly arranged, collagen fibers and few visible cellswithstands unpredictable stressesdeeper layer of skin; capsules around organs

Figure 5.17b,iFigure 5.17aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)(b)FibroblastnucleiGlandductsBundles ofcollagen fibersGroundsubstancea: The McGraw-Hill Companies, Inc./Dennis Strete, photographer

5-*Adipose Tissueadipose tissue (fat) tissue in which adipocytes are the dominant cell type

space between adipocytes is occupied by areolar tissue, reticular tissue, and blood capillaries

fat is the bodys primary energy reservoir

the quantity of stored triglyceride and the number of adipocytes are quite stable in a personfat is recycled continuously to prevent stagnationnew triglycerides are constantly synthesized and storedold triglycerides are hydrolyzed and released into circulation

provides thermal insulation

anchors and cushions organs such as eyeball, kidneys

contributes to body contours female breast and hips

on average, women have more fat than men

too little fat can reduce female fertility

most adult fat is called white fat

brown fat in fetuses, infants, children a heat generating tissue

5-*Adipose Tissueempty-looking cells with thin margins; nucleus pressed against cell membraneenergy storage, insulation, cushioningsubcutaneous fat and organ packingbrown fat (hibernating animals) produces heat

Figure 5.18b,iFigure 5.18a(a)(b)Lipid inadipocyteAdipocytenucleusBloodvessela: The McGraw-Hill Companies, Inc./Dennis Strete, photographerCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Cartilagesupportive connective tissue with flexible, rubbery matrix

gives shape to ear, tip of nose, and larynx

chondroblasts produce matrix and surround them selves until they become trapped in little cavities (lacunae)

chondrocytes cartilage cells in lacunae

perichondrium sheath of dense irregular connective tissue that surrounds elastic and most hyaline cartilage (not articular cartilage)contains a reserve population of chondroblasts that contribute to cartilage growth throughout life

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 cartilage

5-*Hyaline 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 speech

Figure 5.19a(a)a: Ed Reschke Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(b)ChondrocytesPerichondriumMatrixLacunaeCellnestFigure 5.19b,i

5-*Elastic Cartilagecartilage containing elastic fibers covered with perichondriumprovides flexible, elastic supportexternal ear and epiglottis

Figure 5.20aCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)(b)PerichondriumElasticfibersChondrocytesLacunaea: Ed Reschke Figure 5.20b,i

5-*cartilage containing large, coarse bundles of collagen fibers never has perichondriumresists compression and absorbs shockpubic symphysis, menisci, and intervertebral discs

Figure 5.21aFigure 5.21b,iFibrocartilage(a)a: Dr. Alvin Telser Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(b)CollagenfibersChondrocytes

5-*Bonebone has two meanings:an organ of the body; femur, mandible; composed of multiple tissue typesbone tissue osseous tissue makes up most of the mass of bone

two forms of osseous tissuespongy bone - spongy in appearancedelicate struts of bone - trabeculaecovered by compact bone found in heads of long bones and in middle of flat bones such as the sternumcompact bone denser calcified tissue with no visible spacesmore complex arrangementcells and matrix surround vertically oriented blood vessels in long bones

5-*Bone Tissue (compact bone)most compact bone is arranged in cylinders that surround central (haversian or osteonic) canals that run longitudinally through shafts of long bonesblood vessels and nerves travel through central canalbone matrix deposited in concentric lamellaonionlike layers around each central canalosteon 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 whole

Figure 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 osteonCentralcanalLacunaeCanaliculiOsteon

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5-*Bloodfluid connective tissue

transports cells and dissolved matter from place to place

plasma bloods liquid ground substance

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 mechanisms

Figure 5.23b,iCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(b)MonocyteErythrocytesLymphocyteNeutrophilsPlatelets

Excitable Tissues Muscular & Nervous Tissueexcitability a characteristic of all living cellsdeveloped to highest degree in nervous and muscular tissues

membrane potential electrical charge difference (voltage) that occurs across the plasma membranes is the basis for their excitationrespond quickly to outside stimulus by means of changes in membrane potentialnerves changes result in rapid transmission of signals to other cellsmuscles changes result in contraction, shortening of the cell

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5-*Nervous Tissuenervous tissue specialized for communication by electrical and chemical signals

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

and neuroglia (glial)protect and assist neuronshousekeepers of nervous system

neuron partsneurosoma (cell body)houses nucleus and other organellescells center of genetic control and protein synthesisdendritesmultiple short, branched processesreceive signals from other cellstransmit messages to neurosomaaxon (nerve fiber)sends outgoing signals to other cellscan be more than a meter long

Figure 5.24b,i(b)DendritesNeurosomaAxonNuclei of glial cellsCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Muscular 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 smooth

5-*Skeletal 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 muscles

Figure 5.25aFigure 5.25b,i(a)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.StriationsMuscle fiber(b)Nucleia: Ed Reschke

5-*Cardiac Musclelimited to the heartmyocytes or cardiocytes are much shorter, branched, and notched at endscontain one centrally located nucleus surrounded by light staining glycogenintercalated discs join cardiocytes end to endprovide electrical and mechanical connectionstriated, and involuntary (not under conscious control)

Figure 5.26aFigure 5.26b,iCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)(b)GlycogenStriationsIntercalated discs Ed Reschke

5-*Smooth MuscleFigure 5.27a(a)Muscle cellsNuclei(b)Figure 5.27b,ia: The McGraw-Hill Companies, Inc./Dennis Strete, photographerCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.lacks 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 vessels

5-*Intercellular Junctionsintercellular junctions connections between one cell and anotherall cells (except blood and metastatic cancer cells) are anchored to each other or their matrix by intercellular junctionsresist stress and communicate with each other

Figure 5.28Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Basement membraneHemidesmosomeTight junctionMembrane proteinIntermediate filamentsGlycoproteinPoreConnexonProtein plaqueDesmosomeGap junctionIntercellular spacePlasma membranePlasma membraneIntercellular spaceMembraneproteinCell nucleusPoreProteins

5-*Tight Junctionstight junction a region in which adjacent cells are bound together by fusion of the outer phospholipid layer of their plasma membranes.in epithelia, forms a zone that complete encircles each cell near its apical poleseals off intercellular spacemakes it impossible for something to pass between cells

Figure 5.28Tight junctionDesmosomeGap junctionCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Desmosomesdesmosomes - patch that holds cells together (like a clothing snap)serves to keep cells from pulling apart resists mechanical stresshooklike J-shaped proteins arise from cytoskeletonapproach cells surfacepenetrate into thick protein plaques linked to transmembrane proteinshemidesmosomes anchor the basal cells of epithelium to the underlying basement membraneepithelium can not easily peel away from underlying tissues

Figure 5.28Tight junctionDesmosomeGap junctionCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Gap Junctionsgap (communicating) junction formed by a ringlike connexonconsists of six transmembrane proteins arranged like segments of an orangesurrounding a water-filled poresions, glucose, amino acids and other solutes pass from one cell to the next

Figure 5.28Tight junctionDesmosomeGap junctionCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*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 duct (epithelial tube that conveys secretion to surface)sweat, 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 intestine

5-*Exocrine Gland Structurecapsule connective covering of most glandssepta or trabeculae extensions of capsule that divide the interior of the gland into compartments (lobes)further divided into smaller lobulesstroma connective tissue framework of the glandsupports and organizes glandular tissueparenchyma the cells that perform the tasks of synthesis and secretiontypically cuboidal or simple columnar epithelium

Figure 5.29Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.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: PancreasKey5-*Types 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 portions

Figure 5.30

5-*Types 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 cells

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Methods of SecretionMerocrine Glandmerocrine glands (eccrine glands) have vesicles that release their secretion by exocytosistear glands, pancreas, gastric glands, and others

apocrine glands primarily merocrine mode of secretionaxillary sweat glands, mammary glands

Figure 5.31aExocytosisNucleusSecretoryvesicle(a) Merocrine glandCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Methods of SecretionHolocrine Glandholocrine glands cells accumulate a product and then the entire cell disintegratessecretion a mixture of cell fragments and synthesized substanceoil glands of scalp, glands of eyelids

Figure 5.31b(b) Holocrine glandCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Membranesmembranes line body cavities and cover their viscera

cutaneous membrane - the skin largest membrane in the bodystratified squamous epithelium (epidermis) over connective tissue (dermis)relatively dry layer serves protective function

mucous membrane (mucosa) lines passageways open to the external environment

serous membrane (serosa) - internal membranesimple squamous epithelium over areolar tissue produces serous fluid that arises from bloodcovers organs and lines walls of body cavities endothelium lines blood vessels and heartmesothelium line body cavities (pericardium, peritoneum and pleura)

synovial membrane - lines joint cavitiesconnective tissue layer only, secretes synovial fluid

5-*Mucous Membranes (Mucosa)lines passages that open to the external environmentdigestive, respiratory, urinary, and reproductive tractsconsists of two to three layers:epitheliumlamina propria areolar connective tissuemuscularis mucosae smooth muscle layerabsorptive, secretory, and protective functionscovered with mucus

Figure 5.32Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Mucous coatCiliaBasement membraneCollagen fibersFibroblastMuscularis mucosaeElastic fibersBlood vesselCiliated cells of pseudostratified epitheliumMucin in goblet cellEpitheliumLamina propriaMucous membrane (mucosa)

5-*Tissue Growthtissue growth increasing the number of cells or the existing cells grow larger

hyperplasia - tissue growth through cell multiplication

hypertrophy - enlargement of preexisting cellsmuscle grow through exerciseaccumulation of body fat

neoplasia development of a tumor (neoplasm)benign or malignantcomposed of abnormal, nonfunctional tissue

5-*Changes in Tissue TypesTissues can change types

Differentiationunspecialized tissues of embryo become specialized mature typesmesenchyme to muscle

Metaplasiachanging from one type of mature tissue to anothersimple cuboidal tissue of vagina before puberty changes to stratified squamous after pubertypseudostratified columnar epithelium of bronchi of smokers to stratified squamous epithelium

5-*Stem Cellsstem cells - undifferentiated cells that are not yet performing any specialized functionhave potential to differentiate into one or more types of mature functional cells

developmental plasticity diversity of mature cell types to which stem cells can give rise

embryonic stem cellstotipotent - have potential to develop into any type of fully differentiated human cellsource - cells of very early embryopluripotent can develop into any type of cell in the embryosource - cells of inner cell mass of embryo

adult stem cells - undifferentiated cells in tissues of adultsmultipotent - bone marrow producing several blood cell typesunipotent most limited plasticity - only epidermal cells produced

5-*Tissue 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 tuberculosis

5-*Wound Healingsevered blood vessels bleed into cut

mast cells and damaged cells release histaminedilates blood vesselsincreases blood flow to areamakes capillaries more permeable

blood plasma seeps into the wound carrying:antibodiesclotting proteinsblood cells

Figure 5.33 (1)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.1Bleeding into the wound

5-*Wound Healingblood clot forms in the tissueloosely knitting edges of cut togetherinhibits spread of pathogens from injury site to healthy tissue

forms scab that temporarily seals wound and blocks infection

macrophages phagocytize and digest tissue debris

Figure 5.33 (2)Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.ScabBlood clotMacrophagesFibroblastsLeukocytesScab formation andmacrophage activity2

5-*Wound Healingnew capillaries sprout from nearby vessels and grow into wound

deeper portions become infiltrated by capillaries and fibroblaststransform into soft mass granulation tissuemacrophages remove the blood clotfibroblasts 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-*Wound Healingsurface epithelial cells around wound multiply and migrate into wound area beneath scab

epithelium regenerates

connective tissue undergoes fibrosis

scar tissue may or may not show through epithelium

remodeling (maturation) phase begins several weeks after injury and may last up to two years

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)

5-*Tissue Shrinkage and Deathatrophy shrinkage of a tissue through a loss in cell size or numbersenile atrophy through normal agingdisuse atrophy from lack of use (astronauts)necrosis premature, pathological death of tissue due to trauma, toxins, or infectionsinfarction sudden death of tissue when blood supply is cut offgangrene tissue necrosis due to insufficient blood supplydecubitus ulcer bed sore or pressure sorepressure reduces blood flow to an areaa form of dry gangrenegas gangrene - anaerobic bacterial infectionapoptosis - programmed cell deathnormal death of cells that have completed their function and best serve the body by dying and getting out of the way

5-*Tissue Engineeringtissue engineering artificial production of tissues and organs in the lab for implantation in the human bodyframework of collagen or biodegradable polyester fibersseeded with human cellsgrown in bioreactor (inside of mouse)supplies nutrients and oxygen to growing tissue

skin grafts already availableresearch in progress on heart valves, coronary arteries, bone, liver, tendonshuman outer ear grown on back of mouse and recent replacement of urinary bladder wall sections

5-*Tissue EngineeringFigure 5.34Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-*Stem Cell Controversypossible treatment for diseases caused by loss of functional cell types by embryonic stem cellscardiac muscle cells, injured spinal cord, insulin-secreting cells

skin and bone marrow stem cells have been used in therapy for years

adult stem cells have limited developmental potentialdifficult to harvest and culture

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