Tetanic contraction

Tetanic Muscle Contraction

Tetanic muscle contraction is a type of muscle contraction which occurs in skeletal muscles, resulting in a stronger prolonged contraction. Tetanic contraction occurs through summation of action potentials travelling into a muscle fibre. As the frequency of the action potentials increases, the muscle has less time to relax and remove the Ca2+ ions in the sarcoplasm which initiated muscle contraction, through the binding to troponin, causing the myosin binding site to be revealed. Once a given frequency has been reached, the muscle fibre doesn't have time to remove all of the Ca2+ in the sarcoplasm before the next action potential, resulting in Ca2+ remaining in the sarcoplasm. As some Ca2+ remains in the sarcoplasm, when the next action potential arrives, more Ca2+ is released from the sarcoplasmic reticulum, resulting in a higher amount of Ca2+ in the sarcoplasm than in the first action potential. This results in a stronger contraction as more Ca2+ is present, so more myosin binding sites are unveiled, therefore more myosin-actin cross bridges can be formed. 

References

1. . Muscle Contraction. http://michaeldmann.net/mann14.html (accessed 23/11/16).