Ap Bio Quest
Nervous and Muscular System 5. Explain what is occurring in the graph below (summation of the twitches). Use the following terms in your explanation: Twitch summation effect, tetanus, and fatique. (4 points maximum)
When rate is high enough that muscle fibers cannot relax at all between stimuli the twitches fuse into one smooth contraction.
Prolonged contraction can result in muscle fatigue due to the depletion of ATP.
Single action potential produces a twitch about 100msec or less and if a second action potential arrives before the muscle fiber becomes completely relaxed the two twitches add together resulting in greater tension.
Summation occurs more as the rate of stimulation increases
Motor neurons usually have their action potential in rapid-fire volleys which results in smooth contraction rather than jerky actions of individual twitches.
Increase in tension during summation and tetanus occurs because muscle fibers are connected to bones.
Muscle fiber contracts and stretches these elastic structure which transmit tension to bones
In summation it causes greater stretching of the elastic structures.
In tetanus the elastic structures are full stretched and all tension is transmitted to the bones by the muscle fiber.
Nervous system produces graded whole-muscle contraction is by varying the rate of muscle fiber stimulation.Ap Bio Quest
Nervous and Muscular System 5. Explain what is occurring in the graph below (summation of the twitches). Use the following terms in your explanation: Twitch summation effect, tetanus, and fatique. (4 points maximum)
When rate is high enough that muscle fibers cannot relax at all between