Unit 2 - Muscle physiology Flashcards
thin filament is made up of what?
- Actin w/myosin binding sites
- Troponin - TnT, TnC, TnI
- Tropomysosin
What is the thick filament called?
myosin
What are the 3 subunits of troponin & what do they do?
- TnT - is permanently bound to tropomyosin
2, TnC - binds to Ca2+ - TnI - inhibits the interaction of myosin with actin
excitation-contraction coupling
series of events linking the action potential to contraction
- AP reaches sarcoplasmic reticulum
- It spreads to
Dihydropyridine receptors
- are T tubule proteins that act as voltage sensors
- when triggered, open the Ca2+ release channels
Triad
one T tubule + 2 lateral sacs (terminal cisternae) on either side
When muscle begins to relax, what 2 proteins deal with the Ca2+?
- Sarcoplasmic Reticulum Ca2+-ATPase (SERCA)
2. Calsequestrin
what is a muscle twitch?
the response of muscle fibers of a motor unit to a single AP. Fibers contract quickly, then relax
difference between fused & unfused tetanus
unfused - still showing small peaks and valleys at maximal stimulation.
fused - flat line (no peaks & valleys) at maximal stimulation
isotonic contraction
load remains constant as the muscle changes length
isokenetic contraction
velocity of shortening remains constant as the muscle changes lenght
isometric contraction
muscle is prevented from shortening, so tension develops at constant muscle length.
concentric contractions
muscle shortens
eccentric contractions
muscle lengthens
name some skeletal muscles that are not attached to bone on both ends
- tongue
- eye muscles
- sphincters
