lecture 14 - muscle contraction Flashcards
what is the definition of a muscle contraction?
To generate the forces and movements used in the regulation of the internal environment and to produce the movements in the external environment
what does skeletal muscle contain?
perimysium
what does the muscle fascicle contain?
Runs the length of the muscle fibre
Perimysium – outer layer – capsule which contains the muscle fibres
what does the muscle fibre/cell contain?
Endomysium surrounds the muscle fibres
Lined by the sarcolemma
Post mitotic – cant undergo cell division – abundant with mitochondria
what does the myofibril do?
Releases calcium for muscle contraction
what does the sarcomere contain?
actin, myosin, I band, A band, H band and M line (there are no overlap o filaments here) and z line
what is the thin filament known as and where is it in the sarcomere?
actin and the I band
what is the thick filament known as and where is it in the sarcomere?
myosin and the A band
what are the 2 regulatory proteins in the thin filaments?
tropomyosin and troponin
what is a muscle contraction initiated by?
the release of calcium
what is step one of muscle contraction?
ATP binds to the myosin head causing myosin to lose affinity for actin.
what is step 2 of muscle contractions?
Myosin binds with ATP, hydrolyses it, then binds to a new actin subunit.
what is step 3 of muscle contractions?
Pi release triggers a neck shift. “Power stroke” returns myosin to its original shape
what is step 4 of muscle contractions?
ADP released to complete the cycle.
why does calcium have to be removed from the cytoplasm?
so that the muscle can relax
