1. Muscular Tissue

2. General description
1) components:
---cell: muscle fiber--myofiber
elongated thread-liked
sarcolemma
sarcoplasm
SER : sarcoplasmic reticulum
---extracellular G.S: CT with BV, LV and N

3. According to the structure and function
2) classification
According to the structure and function
skeletal muscle: striated voluntary m.
cardiac muscle: striated involuntary m.
smooth muscle: unstriated involuntary m.
smooth muscle
skeletal muscle
cardiac muscle

4. Skeletal muscle

5. Often called Striated or Voluntary Muscle
Has striations that are visible under light microscopy
Under voluntary control
Attached to skeleton ( skeletal)

6. Characteristics of Skeletal Muscles
Muscle cells are elongated fibers with many peripheral nuclei
Each muscle fiber contains many myofibrils
Each myofibril contains many microfilaments

7. Connective tissue coverings
(responsible for force transduction):
Epimysium:
surround collection of fascicles
Perimysium:
surround fascicle
Endomysium:
surround individual fibers

8. Entire muscle A muscle fibre epimysium Perimysium Endomysium
Fasciculus of muscle fibres
Endomysium
A muscle fibre

9. 1) microstructure of skeletal muscle fiber
① long cylindrical um
in diameter,1-40mm long
② multinucleate, nuclei are ovoid, distributed under sarcolemma
③ filled with longitudinal parallel-arranged myofibrils

10. Longitudinal section
Transverse section

11. muscle fiber
myofibril
Thin Filaments
Thick Filaments

12. myofibril:
1-2um in diameter
cross striation: light band -I band,
dark band- A band

13. --A band: M-line, H-band --I band: Z-line

14. --A band (except H band):
Thin Filaments
Thick Filaments
H band:
only Thick Filaments
--I band:
only Thin Filaments

15. sacromere:1/2 I band, A band ,1/2 I band
the smallest structural and functional unit of myofibril

16. ---thick myofilament: composed of myosin: ---thin myofilament:
2) Ultrastructure of myofiber
myofibril:
---thick myofilament:
composed of myosin:
---thin myofilament:
Compose of
A. actin
B. tropomyosin
C. troponin:

17. Transverse tubule
(T tubule):
---definition: sarcolemma and basement membrane invaginate into sarcoplasm to form a transverse distributed tubular system
---location: A-I junctional part
---function: transfer the information into cytoplasm

18. ③ Sarcoplasmic reticulum:
---definition: A longitudinal distributed tubular system formed by smooth endoplasmic reticulum
Sarcoplasmic reticulum

19. H-A band: longitudinal enclose myofibril-- longitudinal tubule
---structure:
H-A band: longitudinal enclose myofibril-- longitudinal tubule
A-I junction: enlarge to form flattened sac —terminal cisternae
triad: one T-tubule + two terminal cisternae
---function: there are calcium pump proteins (ATPase) on membrane, so it can store and release calcium ions
triad

20. Cardiac muscle

21. 1) Microstructure of
cardiac muscle
① short column in shaped, 100um long,15um in diameter, with branches, the branches associated with each other to form a network
②  1-2 ovoid nuclei, centrally-located
③  striated, but no very clear
④  intercalated disc: junctional part
LM: dark striation across the cardiac fibers

22. Cardiac muscle

23. Cardiac muscle: show intercalated disc

24. 2) Ultrastructure of cardiac muscle
similar to skeletal muscle, composed of thick, thin filament and have sarcomere
①     myofibril have different diameter, the boundary of myofibril is not very clear

25. (skeletal muscle : A-I junctional part)
② transverse tubule are thicker, located at Z-line level
(skeletal muscle : A-I junctional part)
③ sarcoplasmic reticulum is not well-developed, form less terminal cisternae
④diad: one T-tubule + one terminal cisternae
(skeletal muscle : triad)
diad
cardiac muscle
triad
skeletal muscle

26. ④ intercalated discs

27. transverse portion longitudinal portion
transverse portion : connection
-intermediate junction
-desmosome
longitudinal portion: communication
-gap junction
transverse portion
longitudinal portion

28. Smooth muscle

29. microstructure of
smooth muscle
①     elongated, spindle-shaped cells, 8um in diameter, 200( )um long
②     rob-liked or ovoid nucleus
③     no striation, no myofibril

31. ① caveola on sarcolemme invaginate into cytoplasm
2) ultrastructure of
smooth muscle
①     caveola on sarcolemme
invaginate into cytoplasm
②  dense patch: under sarcolemma
dense body: in sarcoplasm
③     intermediate filament:
caveola
dense body
dense pach

32. smooth muscle under SEM

33. Compare with three muscle tissues

34. 1. The location of T tubules of cardiac muscle differ from those of skeletal muscle, the former lie at the
A. A-I junctions B.I bands
C. A bands D.M lines
E. Z lines √

35. √ 2. Sarcoplasmic reticulum of muscle fiber is composed of
A. lysosome B. mitochondria
C. microsome D. RER
E. SER √

36. 3.The cell junction which transmit rapidly an electrical impulse between adjacent smooth muscle cells is
A. tight junction B. intermediate junction
C. gap junction D. desmosome
E. semidesmosome √

37. Questions:
Describe the characteristics of muscle tissue.
Compare the similar with the difference for three kinds of muscle cells according to their fine structure and ultrastructure.