Chapter 10 Highlights Flashcards
Myocyte
Muscle cell
Sarcoplasm
Myocyte cytoplasm
Sarcolemma
Myocyte plasma membrane
Sarcoplasmic Reticulum (SR)
- Modified endoplasmic reticulum
- Forms web-like network surrounding myofibrils
- Varies in structure in three types of muscle tissue
- Stores and released calcium ions
Myofibrils
- Bundles of specialized proteins
- Allow for contraction
Composition of skeletal muscle tissue
Fibers and endomysium
Skeletal muscle (organization)
- Surrounded by epimysium
- Contains muscle fascicles
Muscle fascicles (organization)
- Surrounded by perimysium
- Contains muscle fibers
Muscle fibers (organization)
- Surrounded by endomysium
- Contains myofibrils
Myofibrils (organization)
- Surrounded by sarcoplasmic reticulum
- Contains sarcomeres (Z line to Z line)
Sarcomere
- Contains thick and thin filaments
Transverse tubules
- Deep inward extensions of sarcolemma
- Surrounds each myofibril
- Continuous with exterior of cell
- Filled with extracellular fluid
Terminal cisternae
- Enlarged sections of SR
- Flank each t-tubule
Triad
Two terminal cisternae plus corresponding t-tubule
Thick filaments
- Myosin
- Binds to actin
Thin filaments
Actin, tropomyosin, and troponin
Elastic filaments
- Single massive, spring-like structural protein (titin)
- Stabilizes myofibril structure
- Resists excessive stretching
Tropomyosin
- Long, rope-like regulatory protein
- Twists around actin, covering up active sites
Troponin
- Small globular regulatory protein
- Holds tropomyosin in place
- Assists with turning contractions on and off
I band
Only thin filaments
Z disc
- In middle of I band
- Structural proteins that anchor thin filaments in place and to one another
A band
- Zone of overlap
- Both thick and thin filaments
- Generate tension during contraction
H zone
Middle of A band where only thick filaments exist
M line
- Dark line in the middle of A band
- Structural proteins hold thick filaments in place
- Serve as anchoring point for elastic filaments
