Muscle tissue consists of elongated cells called muscle fibers that contract through the interaction of myofilaments within myofibrils. There are three main types of muscle: skeletal, smooth, and cardiac. Skeletal muscle fibers are striated and multinucleated, containing bundles of myofibrils with sarcomeres made up of overlapping actin and myosin filaments that generate contraction. Smooth muscle cells are spindle-shaped and contain a cytoskeletal domain with thin filaments and a contractile domain with interspersed thin and thick filaments. Cardiac muscle forms a branching syncytium with intercalated discs connecting adjacent cells.

1. MUSCLE TISSUE

2. MUSCLE TISSUE
 // AGGREGATES OF SPECIALIZED
ELONGATED CELLS, PRIMARY
FUNCTION IS CONTRACTION
 INTERACTION OF MYOFILAMENTS

3. CLASSIFICATION
 STRIATED
SKELETAL
VISCERAL STRIATED
CARDIAC
 SMOOTH

4. SKELETL MUSCLE
 MUSCLE FIBERS/CELLS
 MESENCHYMAL, FUSION OF MYOBLAST
 SIZE VARIABLE
 ENDOMYSIUM
 PERIMYSIUM, FASICLES
 EPIMYSIUM

5. MUSCLE FIBER
 LONGITUDINAL
 MULTINUCLEATED
 CROSS STRIATIONS
 TRANS. SECTION
POLYGGNOL WITH
FLAT NUCLEI
 10—100 micrometer

6. MUSCLE FIBER
 SARCOLEMMA
 SARCOPLASM
 MYOFIBRILS MYOFILAMENTS
 SARCOPLASMIC REITCULUM

9. MYOFIBRILS
 LONGITUDINALLY ARRANGED
SUBUNITS WITHIN A FIBER
 COMPOSED OF BUNDLES OF
MYOFILAMENTS
 ACTUAL CONTRACTILE ELEMENTS
 ARRANGMENT CROSS STRIATIONS
 SARCOMERE

10. CROSS STRIATIONS
 STAINED UNSTAINED
PREPARATIONS
 A BAND( DARK) I BAND
( LIGHT)
 A BAND MYOSIN FILAMENT
BIREFRINGENT
ANISOTROPIC
CENTER OF SARCOMERE
H ZONE & M LINE
 I BAND ACTIN FILAMENT
MONOREFRINGENT &
ISOTROPIC
ADJACENT SARCOMERE
Z LINE

11. THIN FILAMENT
 F ACTIN TROPOMYOSIN &
TROPONIN
 F ACTIN double stranded
polarized helix, polymers of G
ACTIN
 Anchored to Z line alpha actinin
 I band, edges A band
 TROPOMYOSIN double helix,
grooves,mask binding sites
 TROPONIN 3 subunits
TnC___Ca
TnT___troponin to tropomyosin
TnI___actin

12. Z LINE
 ZIG ZAG
 FILAMENTOUS +Z MATRIX
 ANCHORS THIN FILAMENTS OF
ADJACENT SARCOMERE THRU ALPHA
ACTININ

13. THICK FILAMENTS
 MYOSIN II
 A BAND
 2 HEAVY & 2PAIRS OF LIGHT CHAINS
 HEAVY MYOSIN rod like part with globular heads
 LIGHT CHAIN heads
 BINDING SITES ATP & ACTIN
 HEADS FORM CROSS BRIDGES b/w THICK & THIN
 H ZONE NARROW CENTRAL REGION WITHOUT
HEADS
 ACESSORY PROTEINS

15. SARCOPLASMIC RETICULUM
 SER
 AI------AI BAND
 TERMINAL CISTERN Gated Ca channel
 T TUBULES voltage sensor protein
 TRIAD
 MITOCHONDRIA & GLYCOGEN
GRANULES

17. Muscle contraction
 SARCOMERE SHORTENS
 > OVERLAP b/w THICK & THIN
FILAMENTS
 A BAND REMAINS SAME
 IBAND SHORTENS

18. CONTRACTION
 ATTACHMENT
 RELEASE
 BENDING
 FORCE GENERATION
 RE ATTACHMENT

22. MUSCLE FIBERS
 RED, WHITE & INTERMEDIATE
 MYOGLOBIN OXYGEN BINDING
PROTEIN
 MITOCHONDRIA CYTOCHROMES
ELECTRON TRANSPORT
COMPLEXES

23. RED WHITE
 SMALL  LARGE
 SLOW TWITCH  FAST TWITCH
 > MYOGLOBIN &  < MYOGLOBIN &
MITOCHONDRIA MITOCHONDRIA
 RESISTANT TO  FATIGUE RAPIDLY
FATIGUE  RAPID CONTRACTION
 SLOW CONTRACTION  > NEUROMUSCULAR
 < NEUROMUSCULAR JUNCTIIONS
JUNCTIIONS  EXTRAOCULAR &
 LONG MUSCLES OF DIGITAL
BACK

24. CARDIAC MUSCLE

26. LIGHT MICROSCOPE
 BRANCHING SYNCITIUM
 10—14 micrometer
 100 micrometer long
 ENDOMYSIUM less well organized,
PERIMYSIUM
 SARCOLEMMA
 NUCLEUS single central
 SARCOPLASM perinuclear
 INTERCALATED DISC

28. ELECTRON MICROSCOPE
 MYOFIBRILS not well demarcated
 SARCOPLASM
Abundunt mitochondria
Sarcoplasmic reticulum
Fat droplets
Glycogen
Lipofuscin pigment granules

29. SARCOPLASMIC RETICULUM
 CISTERNS narrower with frequent
anastomosis
 T tubules are wider, external lamina
 T tubules at the level of Z band
 No dilated terminal cistern
 DIAD

31. INTERCALATED DISC
 L/M Cross bands 0.5
—1 micrometer
 Specialized areas of
cell junction
 Step wise
 Zonula adherens,
desmosomes, gap
junction

32. SMOOTH MUSCLE
 SPINDLE SHAPED CELLS, SMALLER
 // TO EACH OTHER (close packing & efficient transfer
of force)
 BASAL LAMINA, RETICULAR LAMINA
 DIAMETER
 LENGTH 20-500 micrmeter
 SINGLE CENTRAL NUCLEUS,(COCK SCREW)
 TRAN. Sect.

34. ELCTRON MICRSCOPE
BASAL LAMINA, RETICULAR LAMINA
Complete covering( nexus)
 PLASMA MEMBRANE
alternnate areas of a) dense submembrane patches
b) uncoated regions
 GAP JUNCTIONS
 BLOOD SUPPLY LESS EXTENSIVE

35. SARCOPLASM
 ORGANELLES at each end of nucleus
 RUDIMENTRY S.E.R
 NO T TUBULES
 TWO CYTOPLASMIC DOMAINS
 CYTOSKELETON & CONTRACTILE
APPARATUS

36. CYTOSKELETAL DOMAIN
 LONGITUDINAL BUNDLES OF
INTERMEDIATE & THIN FILAMENTS
ASSOCIATED WITH DENSE BODIES
 DENSE BODIES alpha actinin

37. Contractile domain
 THIN & THICK FILAMENTS
 1:15
 THICK FILAMENTS ARE LABILE
 OBLIQUE TO CYTOSKELETON
 SUB MEMEBRANOUS DENSE BODIES
 TRANSMEMBRANE PROTEINS
 FBRONECTIN & LAMININ
 DISTRIBUTION & TRANSMISSION OF FORCE