Skeletal muscle Flashcards
Anchor thin filaments to z disks?
Anchor z disks to each other?
Anchor z disk to membrane?
- @actinin, nebulin, cap Z
- Desmin, plectin
- Vinculin, dystrophin
Desmin related myopathy
Duchenne muscular dystrophy
- Desmin aggregates instead of filaments
- Xlinked. Inability to synthesize dystrophin
T/F: Cross bridges pull actin towards each other resulting in muscle shortening
False. Sarcomere shortening
What does TnI bind?
Actin > inhibits contraction
Clostridium botulinum toxin
Blocks release of Ach
Why is latent period in isotonic contraction longer?
We need to recruit many SI heads to lift the weight
Shortening velocity = 0 when
L = Max isometric T
_ responsible for passive elastic properties of relaxed fibers
Active tension from _
- Titin
- Cross bridges
At L0?
60% of L0?
175% of L0?
- Greatest isometric active tension
- No active tension
- No active but high passive tension
Muscles that are fatigued have _ shortening velocity and _ relaxation rate.
Decreased, slower
Causes of fatigue from high intensity/short duration(3)
- AP conduction failure
- Lactic acid buildup
- Inhibition of cross bridge cycle
Causes of fatigue from low-intensity/long duration(2)
- Ca high in cytosol > proteases
- ATP depletion
Strongest motor units are _
Fast glycolytic units
More motor units > _ shortening velocity
Increased
Involuntary tetanic contraction
Muscle cramps
