KINE 1P90 Lecture Notes - Lecture 4: Endoplasmic Reticulum, Ford Power Stroke Engine, Atp Hydrolysis

• School: Brock University
• Department: Physical Education and Kinesiology
• Course: KINE 1P90
• Professor: Klentrou Panagiota

Document Summary

Smallest unit of contraction within a skeletal muscle: sarcomere (sarcomeres make up a myofibril) Function of tropomyosin: to prevent myosin cross bridges from attaching to the thin filaments. Each myofibril is made up of rod-like proteins (contractile proteins) Contraction happens when the thin filaments close up towards the center, sarcomeres contract. Sarcomere is the functional unit of a muscle fibre. The area around the center of the sarcomere is called the h-zone, disappears/becomes darker during contraction. Head pulls the thin filaments towards the center in the contraction. Muscle contracts (shortens) when each sarcomere contracts. Troponin (mickey mouse ears) is attached to tropomyosin. Troponin needs to be attached to calcium to detach from tropomyosin. Power strokes- pulls, like a rowing exercise. 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 actin filaments (cross- bridge) and pull them towards the centre of the sarcomere.