KINE 2011 Chapter 4.8: Frequency of Stimulation and how it affects contractile activity

• School: York University
• Department: Kinesiology & Health Science
• Course: KINE 2011
• Professor: Ali Abdul Sater

Document Summary

F(cid:396)e(cid:395)ue(cid:374)cy of sti(cid:373)ulatio(cid:374: whole muscle tension depends on, number of muscle fibers, tension developed by each contracting fiber, factors affecting tension developed, frequency of stimulation, length of fibre on onset of contraction, extent of fatigue, thickness of fibre. Twitch summation & tetanus: single ap in fiber products a twitch, contractions w/long duration & greater tension can be achieved by repeated stimulation of fibre. If muscle has related completely before next ap, the 2nd twitch will be identical to first twitch. If (cid:373)us(cid:272)le fi(cid:271)re is sti(cid:373)ulati(cid:374)g so rapidl(cid:455) where there"s (cid:374)o ti(cid:373)e to rela(cid:454) (cid:271)/t sti(cid:373)uli- results in contraction of max strength called tetanus: tetanus contraction is 3-4 times stronger than single twitch. Molecular mechanism of tetanus twitch summation: frequency increases- tension development increase until maximum tetanic achieved. If ap & twitches occur far apart, ca2+ is pumped back into lateral sacs b/t ap. If ap occurs shortly after first, more ca2+ is released that taken back in.