muscular tissue prof. ji-cheng li (zhejiang university school of medicine)
DESCRIPTION
Muscular Tissue Prof. Ji-Cheng Li (Zhejiang University School of Medicine). General description 1) components : ---cell: muscle fiber--myofiber elongated thread-liked sarcolemma (cell membrane) sarcoplasm (cytoplasm) sarcoplasmic reticulum (SER ) - PowerPoint PPT PresentationTRANSCRIPT
Muscular TissueMuscular Tissue
Prof. Ji-Cheng LiProf. Ji-Cheng Li
(Zhejiang University School of Medicine)(Zhejiang University School of Medicine)
General description
1) components:
---cell: muscle fiber--myofiber
• elongated thread-liked
• sarcolemma (cell membrane)
• sarcoplasm (cytoplasm)
• sarcoplasmic reticulum (SER )
---extracellular G.S: CT with BV, LV and N
2) classification
According to the structure and function
• skeletal muscle: striated voluntary m.
• cardiac muscle: striated involuntary m.
• smooth muscle: unstriated involuntary m.skeletal muscle cardiac muscle smooth muscle
Skeletal muscleSkeletal muscle
Often called striated or voluntary muscle– Has striations that are visibl
e under light microscopy
– Under voluntary control
– Attached to skeleton ( skeletal)
• Characteristics of
Skeletal Muscles
– Muscle cells are
elongated fibers with
many peripheral nuclei
– Each muscle fiber
contains many myofibrils
– Each myofibril contains
many microfilaments
Connective tissue coverings (responsible for force transduction):
Epimysium: surround entire muscle
Perimysium: surround fascicle
Endomysium: surround individual fibers
Epimysium
Entire musclePerimysium
Fasciculus of muscle fibres Endomysium
A muscle fibre
1) Microstructure of skeletal muscle fiber
① long cylindrical 10-100um
in diameter,1-40mm long
② multinucleate, nuclei are ovoid, distributed under sarcolemma
③ filled with longitudinal parallel-arranged myofibrils
Longitudinal section Transverse section
muscle fiber
myofibril
Thin Filaments Thick Filaments
myofibril:• 1-2um in diameter
• cross striation: light band --I band,
dark band-- A band
I bandA band
H-band
Z-line M-line
--A band: M-line, H-band--I band: Z-line
--A band (except H band):
Thin Filaments
Thick Filaments
• H band:
only Thick Filaments
--I band:
only Thin Filaments
sacromere:1/2 I band, A band ,1/2 I band the smallest structural and functional unit of
myofibril
sacromere
2) Ultrastructure of myofiber myofibril:
---thick myofilament: • Composed of myosin:
---thin myofilament: • Compose of• A. actin• B. tropomyosin• C. troponin:
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
③ Sarcoplasmic reticulum:---definition: A longitudinal distributed tubular s
ystem formed by smooth endoplasmic reticulum
Sarcoplasmic reticulum
---structure: H-A band: longitudinal enclose myofibril-- longitudinal tubule
terminal cisternae: flattened sac, A-I junction
•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
Cardiac muscleCardiac muscle
1) Microstructure of cardiac muscle• ① short column in shaped, 100um long,15um in d
iameter, with branches, the branches associated with each other to form a network
• ② 1-2 nuclei, centrally-located• ③ striated, but no very clear• ④ intercalated disc: junctional part• LM: dark striation across the cardiac fibers
Cardiac muscleCardiac muscle
Cardiac muscle: show Cardiac muscle: show intercalated disc
2) Ultrastructure of cardiac muscle
similar to skeletal muscle, composed of thick, thin filament and have sarcomere
Different:
① myofibril have different diameter, the boundary of myofibril is not very clear
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) skeletal muscle
cardiac muscle
diad
triad
④ intercalated discs transverse portion
longitudinal portion
transverse portion : connection -intermediate junction -desmosome longitudinal portion: communication -gap junction
transverse portion
longitudinal portion
Smooth muscleSmooth muscle
1) microstructure of smooth muscle ① elongated, spindle-shaped cells, 8 um in di
ameter, 200( 20-500)um long ② only one nucleus ③ no striation, no myofibril
smooth muscle
smooth muscle
Neuroanglion
2) ultrastructure of smooth muscle① caveola on sarcolemme invaginate into cytoplasm② dense patch: under sarcolemma dense body: in sarcoplasm③ intermediate filament:
caveola dense body dense pach
smooth musclesmooth muscle under SEM under SEM
Compare with three muscle tissues
• 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√
• 2. Sarcoplasmic reticulum of muscle fiber is composed of
• A. lysosome B. mitochondria
• C. microsome D. RER
• E. SER√
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√
• 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.