, Muscle Tissue,The Key Points of Muscle tissue The Types of muscle tissue and their microstructure The Ultrastructure of skeletal muscle, Cardiac muscle and smooth muscle. The molecular construction of myofibril and contraction-mechanism of skeletal muscle,2,1.fi:$ffifi, muscle fiber,A:fi,$fl,fi flflA: 偼傐 ,%q:(偼傐) (.) %:C偼傐. .3 C3,.,3,= muscle fiber: muscle cell = sarcolemma =cell membrane =ffi sarcoplasm = cytoplasm fi=ffifi sarcoplasmicreticulum (SR) = smooth endoplasmic reticulum (sER),4,3.y,skeletal muscle 偼傐 Visceral skeletal muscle cardiac muscle smooth muscle .$. . .EM.y$,5,6,s.偼傐skeletal muscle,skeletal muscle 偼傐L!,endomysium, perimysium$, epimysium Connective tissue of muscle is given a distinct set of names. Epimysium DCT,7,fi: fl% $: 偼傐$ :$fl: $,o A: flfi.fi, fiy5, fl,fl% muscle satellite cell,8,1.LM : :fi,fiy,1-40mm,$10100um :fi.fl$:fi,fo $:$myofibril,y : myofibrilfi,9,偼傐:,10,11,Cross-striations in each myofibrils y: dark band=A band (anisotropic),H band CHall“ M line CMittle“$,”3 ”3,y:light band = I band (isotropic) Z line CZwischem“”,3,2. Cross-striations,$H y, H y$M : $fiZ ,12,13,14, myofibril,thin filaments thick filaments :zAyAfi.fl M.fl: :Z, ,Hy yfi, H yfi,Ay fl,15,myofibril,$.fl,fi,16,$f $,fi,17,3; Sarcomere,$1/2y+y+1/2y $ (fi2.12.5mm)o ;fi,18,flZ fi,偼傐fl $fl$,fl, ;yfi 8, fyfi f,19,4 偼傐:fi Sliding filament mechanism,1.Mfi:2.y:3.;,Actinfi$,Tropomyosin $,thin filament,Troponinfl$C TnT, TnI, TnC 3 Myosin$fi thick filament,yfi,21,22,23,Troponin,fl$: TnT:fl,$,TnI咘:fi,fi$,fl$, TnC: G 2+ qfl$,$4G+A,Tropomyosin $C3,(Myosin,$3C),Actin,fi$C3,fis:transverse tubule,A.I, 8:terminal cisternae C23s:longitudinal tubule,hLs,s , (3)fi: sarcoplasmic reticulum,fl;Ca2+, L,? flTriad : T tubule +fl $Ls$fi8 Cterminal cisternae3fi Mt.$,(l)fis:ffifi,24,triadLfis,SERflfl TnC $ fi$Afl fl ATPaseADP+ flfl fi;,偼傐, fi fis, $,?,25,s. cardiac muscle,26, : fi,$y $:, : $,: fl偼傐,$, A:$, ,1. fi:,27,f$;,.q.,28,.A,(1)fl偼傐fi ()fisflfi fisfl fifl,8fisfl (3)fl fi #:$,() (),29,fl$ T-tubules , Z-lines T-tubules fis fl(diad),2. EM,30,5,3$,fi, ,5,Intercalated disks : Gap junction : $;,31,32,33,. ,smooth muscle,34,:,$ : $,fl , $, :fl.fl ,35,y$: 5s. .Rs .%s,36,SmoothMuscle,37,38,(1)fl,()$ (3)$.fl.$.,Cfi$3 dense bodies fl,ffi,fl,Dense patch,fl,39,fiQ-fi fis fi Gap junction,40,41,fi,42,偼傐;,fis,偼傐 y, Zfl,fi,fl,43, fifl fl.,$ fisfl fl.$,Muscle tissue is composed of muscle cells that have the property of contractility. Muscle cells are often termed muscle fibers because of their elongated and thread-like shape. The cell membrane of muscle fibers is called sarcolemma, and the cytoplasm is termed sarcoplasm. The sarcoplasmic reticulum is referred to the smooth endoplasmic reticulum. Based on the morphologic and functional characteristics, muscle tissue can be distinguished as three types, skeletal muscle, cardiac muscle and smooth muscle. Skeletal and cardiac muscles are also referred as striated muscles due to the presence of cross striations in muscle cells. Functionally, skeletal muscle is often called voluntary muscle since it is capable of voluntary control; on the other hand, cardiac and smooth muscles are also described as involuntary muscles since they are under inherent autonomic control. Skeletal muscle consists of muscle fibers, bundles of very long cylindrical multinucleated cells. The oval nuclei are usually found at the periphery of the cell under the sarcolemma. The longitudinally sectioned skeletal muscle fibers show distinct cross striations of alternating light and dark bands. The sarcoplasm of skeletal muscle fibers is filled with long cylindrical myofibrils that consist of end-to-end chainlike arrangement of sarcomere. The sarcomere is the structural and functional unit of the myofibri. Each sarcomere is composed of thick and thin filaments. The sarcolemma extends transversely into the sarcoplasm to form transverse(T) tubules surrounding each myofibril at the rejoin of the junction of the dark and light bands. Adjacent to opposite sides of each T tubule are expanded terminal cisternae of the sarcoplasmic reticulum. The complex of a T tubule and two terminal cisternae is called the triad.,44,Cardiac muscle is composed of short cylindrical and branched cells with only one or two centrally located nuclei. Cardiac muscle fibers also exhibit cross striations. In addition, they show densely staining transeverse lines, called intercalcated discs, which represent junctional complexes between adjacent cardiac muscle fibers. Cardiac muscle has the same types and arrangement of myofilaments as skeletal muscle. The sarcoplasm of cardiac muscle is not as well organized as that of skeletal muscle. It does not usually separate bundles of myofilaments into discrete myofibrils. The terminal cisternae are small, which interact with the T tubules located at the level of Z line to form diads. Smooth muscle is composed of fusiform and nontrated cells. The nuclei of smooth muscle cel