Exam 2: Myology Flashcards
Myology
-Study of muscles
Functions of skeletal muscle tissue
- Body movement
- Maintenance of posture: muscle tone (continual contraction) keeps body from collapsing/falling
- Temperature regulation: heat produced when muscles contract
- Storage and movement of materials: sphincters (circular muscles around openings) open and close
- Support: helps hold organs in place ex: abdominal and pelvic floor muscles
Gross Anatomy
- made up of muscle fibers=muscle cells
- each skeletal muscle is an organ
- many skeletal muscles work in groups
Tendons/Aponeuroses
- tendons attach many skeletal muscles to bones (dense regualr CT)
- aponeuroses: flattened sheetlike tendon
Endomysium
-surrounds muscle fiber
Fasicles
-groups of muscle fibers
Perimysium
-surrounds fasicles
Epimysium
-surround sentire muscle
Deep Fascia
-surrounds all the CT wrappings
Superficial Fascia
-subcutanious layer is superficial to deep fascia
Sarcolemma
-muscle cell membrane
Sarcoplasm
-cytoplasm of skeletal fibers
Internal characterists of muscle cell (sarcoplasmic reticulum)
- has organelles like lysosomes, ribosomes, and ER called sarcoplasmic reticulm
- SR function: store calcuim ions Ca2+ and releases them when muscle contracts
Transverse Tubules (T-tubules)
-conduct nerve impulses quickly from sarcolema through muscle fiber
Compositon of Muscle Fibers
- mainly made of myofibrils
- run length of muscle-as long as muscle fiber
- no nuclear or cellular wrapping
Myofilaments
- compose myofibrils
- many needed to run length of muscle
- protein filaments
- each thick myofilament surrounded by 6 thin myofilaments
- arrangement of thick and thin filaments gives muscle its striations
Myosin
- thick myofilaments
- fixed length
Actin
-thin myofilaments
I Bands
- light bands (I-LIGHT)
- thin myofilaments only
A Bands
- dark bands (A=DARK)
- overlapping thick and thin myofilaments
Z disc (Z Line)
- dark structure in the middle of an I band
- thick myofilaments only
H Zone (H Band)
-a lighter central region in the middle of an A band
M Line
- dark line in the middle of H zone
- thick myofilaments attach here
Sarcomere
- run from Z disc to Z disc
- functional contractile unit
- many along length of muscle fiber
- shorten and narrow when muscle contracts
Sliding Filament Model of Contraction
When Muscle Contracts:
- thick and thin myofilaments slide over one another
- length of each sarcomere shortens and narrows, muscle contracts
- H zones narrow and I bands narrow
**Z disc, M line, A band, thick and thin myofilaments stay the same size (do not shorten or narrow)
