BIOM20002 Lecture Notes - Lecture 13: Type Ii String Theory, Glycolysis, Tetanus
Document Summary
Would recruit these first for low force contractions. Fast twitch: type iia (oxidative-glycolytic) fibres and type iib (glycolytic). Would recruit these in addition to slow twitch when we need to increase force of contraction. They need to maintain tone to keep posture. These fibre types differ in rate of myofibrillar atpase, identity of contractile and regulatory proteins as well as proteins of the sr and ttubules. If a 2nd ap hits before ca has a chance to be retracted into sr, more ca is released. More calcium causes a summation of the contraction. This saturates crossbridges and we get a maximal contraction. Rate that ca is taken back into sr determines length of twitch. If it is taken up faster it will be a fast twitch fibre and contraction has a shorter direction. Fast twitch will require higher frequency of ap.
