Infrastructure of Skeletal Muscle Flashcards
All muscle has what property?
contractility
3 types of muscle fibers
- smooth
- cardiac
- skeletal
Skeletal muscle fibers are mononucleated or multinucleated?
multinucleated
The “I” in ‘I-bands’ stands for _______
isotropic
The “A” in ‘A-bands’ stands for _______
anisotropic
the _____ anchors the thin filaments of sarcomeres
Z-band
the ______ anchors adjacent thick filaments
M-line
________ is the section of the sarcomere with only thick filaments, there is no overlap with the thin filaments
H-band
__________: the space between adjacent myofibrils
intermyofibrillar space
_________: anchor thin filaments
Z-lines
Z-lines are composed of _______ and _______
- (alpha)-actin
- Z-line filaments
M-lines are composed of _________ and ________
- M-line filaments
- creatine kinase
the M-line contains contain ____% of the total creatine kinase for the muscle fiber
10%
4 things contained within the intermyofibrillar space
- sarcoplasmic reticulum
- mitochondria
- glycogen
- lipids
3 intermediate anchoring filaments in the sarcomere
- vinculin
- desmin
- vimentin
_________: large springy globular protein that anchors M-bands and imparts a portion of the passive elastic component of muscle
titin
_________ is the largest protein yet discovered and is the third most abundant muscle protein, comprising approximately 10% of the combined muscle protein content
titin
the elasticity of titan helps to what?
restore the stretched sarcomere (muscle) back to its correct length
Ratio of thick to thin filaments in muscle
6 thin: 1 thick
the sarcolemma is attached to the endomysium via _______________ and invades the cell via the _____________
- connective tissue reticular fibers
- T-tubule system
_________: cytoskeletal protein located on the inner surface of the sarcolemma which is involved in structural integrity - anchoring of actin and may help in regulation of membrane proteins (ex. ion channels)
dystrophin
What is the function of dystrophin?
the transmission of force to the extracellular matrix
________: an X-linked disease where dystrophin is absent and muscle cells are unable to survive
muscular dystrophy
What symptom of muscular dystrophy would show up in a blood analysis?
creatine kinase levels as much as 10 x the normal level
What would a severely abnormally high level of creatine kinase potentially indicate?
Muscular dystrophy
3 fields of research for a potential cure for muscular dystrophy
- stem cell research
- myostatin inhibitor trials
- follistatin activator trials
the “Belgian Blue” is a cattle breed that exhibits what genetic abnormality?
myostatin knockout
The sarcolemma-T-tubule interconnection triad is located where?
at the A-I junction of sarcomeres
Ca++ is released along the ____________ and reuptake occurs at the __________
- A-I junction
- M-line
Ca++ reuptake is regulated by __________
intracellular Ca++ levels
intracellular ↑ in Ca++ stimulate ___________ on the sarcoplasmic reticulum
ATP-driven Ca++ pump
the Ca++/ATP pump moves ___ Ca++ ions for every molecule of ATP consumed
2
Ca++ pumps are concentrated along the _____________ of the sarcoplasmic reticulum
longitudinal sarcotubules
Ca++ binding within the sarcoplasmic reticulum is achieved by ___________
calsequestrin
According to the Sliding Filament Hypothesis, which sections of the muscle cell will decrease in length with contraction?
- sarcomere
- I band
- H band
According to the Sliding Filament Hypothesis, which sections of the muscle cell will have no change in length with contraction?
- A bands
- M bands
