KINE 1P90 Lecture Notes - Lecture 4: Sliding Filament Theory, Endoplasmic Reticulum, Myosin Head
Document Summary
Each myofibril is made up rod-like proteins (contractile proteins) During contraction h zone disappears, and becomes darker, h zone does not move during contraction. The cross bridge has an affinity to bind with actin only is tropomyosin is not blocking it. Tropomyosin must be removed for contraction, which can be done by troponin, If calcium is added, troponin will be pulled away from tropomyosin, which can then attach to actin and contraction can begin. Cross bridge interaction between actin and myosin brings about muscle contraction by means of the sliding filament mechanism. Sarcomeres contract when myosin filaments make contact with the actin filament ( cross bridges) and pull them towards the centre of the sarcomere. The length of the thick and thin filaments do not actually change. Decrease ca 2+ turns off sliding process. Thin filaments on each side of sarcomere slide inward over stationary thick filaments toward centre of a band during contraction.