Muscle Ultracstructure Flashcards
What is the order of skeletal muscle tissue?
- Muscle
- Muscle bundle
- Muscle fibers
- Myofibril
- Myofilament
What are the three layers of connective tissue that enclose skeletal muscle?
- Epimysium - surrounds the muscle
- Perimysium - surrounds muscle bundles
- Endomysium - surrounds muscle fibers
Fibers run _______ in muscles that contract a relatively small fraction of resting length
parallel
What is the sarcolemma?
It is the cell membrane that surrounds the muscle fiber
What are transverse tubules?
a network of tubules made of sarcolemma
What is the sarcoplasmic reticulum?
the storage site of Ca in resting muscle
What are the parts of a triad?
2 terminal cisterna and 1 T-tubule
Neuromuscular junction
where motor nerve fiber endings meet the sarcolemma
Sarcoplasm
intracellular colloidal substance in which all organelles are suspended
bathes the myofibrils
Mitochondria
provides cell with source of chemical energy
Lysosome
contain proteolytic enzymes known as cathepsins
Myofibril are ____ in diameter
1-2 um
I band
light band, is isotropic when viewed with polarized light
contains actin only
A band
dark band, is anisotropic in polarized light
contains myosin and actin
________ bisects the I band
Z line
______ bisects the center of A band
M line
H zone
center of A band (myosin only)
pseudo H zone
region within H zone (myosin tail only)
Sarcomere
unit length between 2 Z lines
includes 1 A band and 2 half I bands
