Physiology: Muscles Flashcards
Twitch
One single contraction: ample time for complete relaxation for the muscle
Summation
Second contraction comes before the first relaxes, piggybacks on first
- (Usually appears stronger, first overcomes series elastic component)
Incomplete Tetany
Saw-tooth appearance
Fast summation
Complete tetany
Smooth sustained contraction
Treppe
Twitches with increasing strength with each successive shock
- Staircase effect
a) Warm-up effect
b) Increased Calcium in the cell, stronger contraction
c) Overcomes series elastic component
Isotonic Contraction
“Same Strength”= Muscle is shortening & limb moving during contraction
Isometric contraction
“Same length”= muscle isn’t shortening, joint is not moving
Eccentric Contraction
Muscle is lengthening in spite of contraction
-Weight forces exceed force of contraction
Series Elastic Component
a) Tendons are in line with muscles: thus called series
b) Muscles must pull slack and stretch out tendons before insertion will move
c) Treppe may in part be overcoming series elastic component
Three Causes of Muscle Fatigue
1) Power moves max: Lack of sufficient ATP to sustain max contraction, or inability to maintain Ach release at myoneural junction
2) Anaerobic activity: H+ from pyruvic aside interferes with Calcium binding to troponin, reducing # of cross bridges that form
Epimysium
Surrounds each whole muscle
Perimysium
Surrounds each muscle fasciculus
Endomysium
Surrounds each individual muscle fiber
Titin
Huge elastic protein (largest known protein, runs from Z-line to Z-line through the myosin filament)
- Maintains alignment
- Elastic Recoil
Nebulin
Inelastic giant protein that align actin filaments, attach them to the Z-disk
