AnatomyDepartmentCMMS,AGU

GENERAL HISTOLOGY4. Muscular

TissueDr. Manal Othman

Biology-232

• ResponsibleforMOST typesofBODYMOVEMENT

• MadeupofgroupsofelongatedMUSCLE cellswithcontractilefilaments

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Terminologies• Sarcolemma• Sarcoplasm• Sarcoplasmic reticulum• Sarcomere

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Classification:Morphology

• STRIATED– Havecharacteristicalterationsofdarkandlightbands,Nonstriated

– Nostriations– Locatedinwallsofbloodvessels,viscera.

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Classification:Function

• VOLUNTARY– Consciouscontrol

• INVOLUNTARY– Noconsciouscontrol

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Classification:MorphologyandFunction

• 3types,morphology/function

SKELETALMUSCLE

CARDIACMUSCLE

SMOOTHMUSCLE

Strong,quickdiscontinuousVOLUNTARYCONTRACTIONStriatedcylindricalnonbranching

Strong,quickcontinuousINVOLUNTARYCONTRACTIONStriated

cylindricalbranchingWeak,slowINVOLUNTARYCONTRACTIONnon-striatedSpindleshape 6

SKELETALMUSCLE• Longmusclefibers• Cylindrical,

multinucleated cells• Ovalnucleifoundat

periphery ofcell,underthecellmembrane

• Striations present• Pinktoredincolor

duetorichvascularsupplyandpresenceofmyoglobin pigments

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SKELETAL MUSCLE FIBERS (H&E picture)

SKELETAL MUSCLE FIBERS

Connectivetissuecoverings

1.Epimysium(denseirreg CT)2.Perimysium

(invagination– Ms bundles)3.Endomysium(delicateCT)

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OrganizationofSKELETALMUSCLEFIBER

• ZLINEordisk• ABAND• IBAND• HBAND–

palearea,centerofAband

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Sarcomere -Smallestsubunitofcontractileapparatus

SKELETAL MUSCLE FIBERS (Sarcomere)

Electronmicroscopicpicture

MOTORENDPLATE

• Myoneuraljunction• Branchingmyelinatedmotornerves– “dilatedtermination”

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CARDIACMUSCLE

• Cross-striatedbandingpattern

• 1or2centrally-locatedpale-stainingnuclei

• Endomysial CT– hasarichcapillarynetwork

• structure&function:diads(1t-tubule&1sarcoplasmicreticulumcisterna)

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CARDIAC MUSCLE FIBERS• Striated, branched cells with intercalated disks

(junctional complexes).

• Contain 1–2 central large pale nuclei.

• Rhythmic contraction.

CARDIAC MUSCLE FIBERS (H&E picture)

§ Only1or2centrally- locatedpalestainingnuclei

§ Containsnumerousmitochondria-occupy40%ormoreofthecytoplasmicvolume

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Electronmicroscopicpicture

§ INTERCALATEDDISK–representjunctionalcomplexesbetweenadjacentcardiacmusclecells

§ 3mainjunctionalspecializations1.Zonulaadherens:(Fasciae

adherentes) – mostprominentfoundintransverseportions,servesasanchoringsitesforactinfilamentsofterminalsarcomeres

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2.Maculaeadherentes(desmosomes)– foundintransverseportions,bindcardiaccellstogethertopreventtheirpullingapartunderconstantcontractileactivity

3.Gapjunction – foundinlateralportions,provideioniccontinuitybetweenadjacentcells

SMOOTHMUSCLE

• Elongated non-striated spindle shaped cells

• Length: 20 um (small bld vessels) & 500 um(pregnant uterus)

• Each cell – oval nucleus located in center

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SMOOTH MUSCLE FIBERS• Elongated, nonstriated, fusiform cells with single

central nucleus (folded and tapers).

• Located in walls of respiratory, GIT, urinary, and blood vessels

SMOOTH MUSCLE FIBERS (H&E picture)

ORGANELLES• Mitochondria

• Sarcoplasmic reticulum –branching network of cisternae

• Transverse tubules – finger-like invaginations of sarcolemma, regulation of Ca+

– Skeletal muscle – TRIAD 2SR + 1TT (Present at AI junction)

– Cardiac muscle – DIAD 1SR + 1TT (present at Z line)

– Smooth muscle – NO T-tubules

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CARDIACMUSCLE

– virtuallynoregenerativecapacitybeyondearlychildhood

- Defectsordamage(eg.infarcts)aregenerallyreplacebyproliferationofconnectivetissue(myocardialscars)

RegenerationofMUSCLETISSUE

SKELETALMUSCLE

– undergolimitedregeneration,sourceorregeneratingcellsisbelievedtobethesatellitecells

SMOOTHMUSCLE

– capableofactiveregenerativeresponse

- Undergomitosis

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