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20 Cards in this Set

  • Front
  • Back
Steps of a Muscle’s Excitation-Contraction Reaction - 1
Acetylcholine triggers an AP in the muscle fibers (excitation of the muscle)
Steps of a Muscle’s Excitation-Contraction Reaction - 2
Excitation causes calcium to be released from the sarcoplasmic reticulum.. Calcium is only allowed in temporarily, it’s pumped back into the SR
Steps of a Muscle’s Excitation-Contraction Reaction - 3
Calcium released by the SR binds to troponin and causes the tropomyosin to shift away from the actin binding sites. Allows myosin to bind to actin.
Steps of a Muscle’s Excitation-Contraction Reaction - 4
Contraction: Myosin heads attach and detach, pulling it myosin towards the center of the sarcomere.
Steps of a Muscle’s Excitation-Contraction Reaction - 5
Contraction ends when Calcium is pumped back into SR
Each Muscle fiber has ____ neuromuscular junction
Depolarization leads to the _________ of each sarcomere in the muscle fiber
At rest, myosin binding is blocked by __________
Tropomyosin fits into the binding spots on the _________
Calcium binds to _______, which releases ________ from actin
Stronger _________s lead to a greater number of motor units being recruited
Summation –
When two AP come close together, the second contraction is stronger.
Sustained muscle contraction –
When acetylcholine builds up in the synaptic cleft and is called “tetanus”
Muscle fatigue –
When the muscle can no longer continue the contraction, despite nervous impulses.
Treppe –
“The Staircase Effect”. After contracting with some frequency (warming up) contractions become stronger with the same level of stimulation. More calcium is available. Head generated increases activity of involved enzymes.
Muscle Tone –
Spinal nerve reflexes that alternately contract motor units throughout the day to maintain muscle health.
Concentric –
Muscles that work by shortening.
Eccentric –
Muscle does work by lengthening.
Isometric contractions –
Muscle length remains the same.
Cross Bridge Cycle
• Calcium binds troponin, troponin causes tropomyosin to shift and let Myosin-ADP attach to actin.//•Power stroke: Myosin rackets forward as ADP is released.//•ATP binds to myosin and causes myosin to fall off actin. // •Hydrolysis of ATP to ADP cocks the head into ready position and the cycle repeats until calcium concentrations fall.