The Tissue The Tissue Level of Level of

OrganizationOrganization

TissueTissue

– Definition – an aggregation of cells in Definition – an aggregation of cells in which each cooperates with all others in which each cooperates with all others in the performance of a given functionthe performance of a given function

– Examples of general functionsExamples of general functions•MovementMovement

•ProtectionProtection

•SupportSupport

•Production of chemicalsProduction of chemicals

Principal Tissue TypesPrincipal Tissue Types

– EpithelialEpithelial– ConnectiveConnective– MuscularMuscular– NervousNervous

Epithelial TissueEpithelial Tissue– FunctionsFunctions

•Coverings and liningsCoverings and linings

•Forms glandsForms glands

– CharacteristicsCharacteristics•Closely packed cellsClosely packed cells

•Continuous sheetsContinuous sheets

•Basement membraneBasement membrane

– Classification based on cell shape and layersClassification based on cell shape and layers•SimpleSimple

•StratifiedStratified

Epithelia and Epithelia and Basement MembranesBasement Membranes

Epithelia of Coverings Epithelia of Coverings & Linings& Linings

– Simple squamousSimple squamous– Stratified squamousStratified squamous– Simple cuboidalSimple cuboidal– Transitional Transitional – Simple columnarSimple columnar– Pseudostratified columnarPseudostratified columnar

Simple Squamous Simple Squamous EpitheliumEpithelium

– 1 layer, flat cells1 layer, flat cells•Thin sheetThin sheet

– Highly adapted to diffusion, osmosis, & Highly adapted to diffusion, osmosis, & filtrationfiltration

Stratified Squamous Stratified Squamous EpitheliumEpithelium

– 2 or more layers2 or more layers•Surface layer is flatSurface layer is flat

•Deep layers are cuboidal or columnarDeep layers are cuboidal or columnar

•Basal cells undergo mitosisBasal cells undergo mitosis

– Function - protectionFunction - protection

Squamous EpitheliaSquamous Epithelia

Simple Cuboidal Simple Cuboidal EpitheliumEpithelium

1 layer, cube-shaped cells1 layer, cube-shaped cells

Lines glands and their ductsLines glands and their ducts

Cells function in secretion and absorptionCells function in secretion and absorption

Transitional EpitheliumTransitional Epithelium

– Similar to stratified squamous Similar to stratified squamous epitheliumepithelium•Surface layer is large, rounded cellsSurface layer is large, rounded cells

– Can be stretchedCan be stretched– Lines hollow structures that expandLines hollow structures that expand– Function – prevents rupture of organFunction – prevents rupture of organ

Cuboidal and Cuboidal and Transitional EpitheliaTransitional Epithelia

Simple Columnar Simple Columnar EpitheliumEpithelium

– 1 layer, column-shaped cells1 layer, column-shaped cells– FunctionsFunctions

•ProtectionProtection

•AbsorptionAbsorption

•SecretionSecretion– Goblet cells Goblet cells

Pseudostratified Pseudostratified EpitheliumEpithelium

– Appear stratified but all cells connect to Appear stratified but all cells connect to the basal laminathe basal lamina

Columnar EpitheliaColumnar Epithelia

Glandular EpitheliumGlandular Epithelium

– Gland – 1 or more cellsGland – 1 or more cells– Function – secretionFunction – secretion– TypesTypes

•Exocrine – to surface or ducts Exocrine – to surface or ducts

•Endocrine – to bloodEndocrine – to blood

Connective TissueConnective Tissue

– Most abundant tissueMost abundant tissue– Functions are variedFunctions are varied– CharacteristicsCharacteristics

•Specialized cells, widely scatteredSpecialized cells, widely scattered

•Rich blood supplyRich blood supply

•Much Much extracellularextracellular matrixmatrix– Non-living substance found outside the cellsNon-living substance found outside the cells– Extracellular fibers Extracellular fibers

Cell Types Found in Cell Types Found in Connective TissueConnective Tissue

– FibroblastsFibroblasts•Secrete the molecules that form the matrixSecrete the molecules that form the matrix

– FibrocytesFibrocytes

Connective Tissue Connective Tissue FibersFibers

– Collagen fibersCollagen fibers•Most common typeMost common type

•WhiteWhite

•Strong, ropelikeStrong, ropelike

•Form ligaments, tendonsForm ligaments, tendons

– Elastic fibersElastic fibers•YellowYellow

•ThinThin

•StretchStretch– Contain elastinContain elastin

Types of Connective Types of Connective TissueTissue

– Loose (Areolar) Connective TissueLoose (Areolar) Connective Tissue– Adipose Tissue Adipose Tissue – Dense Connective TissueDense Connective Tissue– CartilageCartilage– Bone Bone – BloodBlood

Loose Connective Loose Connective TissueTissue

• Fibers not abundant, do Fibers not abundant, do not prevent stretchingnot prevent stretching

• Examples of locationsExamples of locations– Between skin and Between skin and

musclesmuscles– Around digestive tractAround digestive tract– Around blood vesselsAround blood vessels

Adipose TissueAdipose Tissue

• Similar to loose Similar to loose connective tissueconnective tissue

• Most of the volume is Most of the volume is adipocytesadipocytes

• Provides padding, slows Provides padding, slows heat loss, food reserveheat loss, food reserve

• LocationsLocations– Wherever there is Wherever there is

loose connective tissueloose connective tissue

Dense Connective TissueDense Connective Tissue

• Lots of collagen fibersLots of collagen fibers

• Examples Examples – TendonsTendons– LigamentsLigaments

• Some has elastic Some has elastic fibersfibers

CartilageCartilage

– Dense network of collagenous fibers & Dense network of collagenous fibers & elastic fibers in a gel-like substanceelastic fibers in a gel-like substance

– Cells – chondrocytes in lacunaeCells – chondrocytes in lacunae•chondroblastschondroblasts

– Perichondrium – surrounds surface of Perichondrium – surrounds surface of cartilagecartilage

Hyaline CartilageHyaline Cartilage

• Most commonMost common

• Provides flexibility and Provides flexibility and supportsupport

• LocationsLocations– Ends of bonesEnds of bones– TracheaTrachea– LarynxLarynx– Embryonic skeletonEmbryonic skeleton

FibrocartilageFibrocartilage

– Visible collagenous fibers with scattered Visible collagenous fibers with scattered chondrocyteschondrocytes

– Provides strength and rigidityProvides strength and rigidity– LocationsLocations

• Intervertebral discsIntervertebral discs

•Symphysis pubisSymphysis pubis

FibrocartilageFibrocartilage

• Visible collagenous Visible collagenous fibers with scattered fibers with scattered chondrocyteschondrocytes

• Provides strength and Provides strength and rigidityrigidity

• LocationsLocations– Intervertebral discsIntervertebral discs– Symphysis pubisSymphysis pubis

BoneBone

• Solid matrix Solid matrix

• Cells – Cells – – Osteocytes in lacunaeOsteocytes in lacunae– OsteoblastsOsteoblasts– Osteoclasts Osteoclasts

• Periosteum surrounds Periosteum surrounds surface of bonesurface of bone

BloodBlood

•FunctionsFunctions– Transport mediumTransport medium– Regulation Regulation – ProtectionProtection

•CompositionComposition– Plasma – fluid Plasma – fluid – Formed elements – cells & cell Formed elements – cells & cell

fragmentsfragments• Red blood cellRed blood cell

• White blood cellWhite blood cell

A Red Blood CellA Red Blood Cell

SEM of RBCsSEM of RBCs

Muscular TissueMuscular Tissue

– Specialized cellsSpecialized cells– Function - contractionFunction - contraction– 3 types3 types

•Skeletal muscleSkeletal muscle

•Cardiac muscleCardiac muscle

•Smooth muscleSmooth muscle

Skeletal Muscle TissueSkeletal Muscle Tissue

• Connected to bonesConnected to bones

• StriatedStriated

• MultinucleatedMultinucleated

• VoluntaryVoluntary

Cardiac Muscle TissueCardiac Muscle Tissue

• Found in the heartFound in the heart

• StriationsStriations

• Intercalated discsIntercalated discs

• InvoluntaryInvoluntary

Smooth Muscle TissueSmooth Muscle Tissue

• Found in walls of Found in walls of

internal organsinternal organs

• NonstriatedNonstriated

• InvoluntaryInvoluntary

Nervous TissueNervous Tissue

• Specialized cellsSpecialized cells

• Function – conduction Function – conduction of electrical impulsesof electrical impulses

• CellsCells– NeuronsNeurons– NeurogliaNeuroglia