Biology 3602A/B Lecture Notes - Lecture 27: Cardiac Muscle Cell, Intercalated Disc, Sliding Filament Theory

• School: Western University
• Department: Biology
• Course: Biology 3602A/B
• Professor: Jim Staples

Document Summary

Contraction of skeletal/cardiac muscle, both of which use sarcomeres. Sarcomeres span through 2 z-disks of 2 microns long; thin and thick filaments. Thin have nebulin; thick have titin, both of which attach to z-disks. Sarcomere of skeletal and cardiac muscle look very similar. When we talk about muscle function we talk about excitation-contraction coupling. Need to get excitation to myofibrils, and myofibrils need to do the contraction. We"ll start out talking about contraction first, just like the sliding filament theory. Thin filament is composed of these g-actins that are polymerized into an f-actin, and that"s a helix. Sitting on top of f-actin helix is tropomyosin (tm), a protein with a coiled coil (2 monomers coiling around e/o and there is 1 of these molecules for every 7 g-actin) A single tm molecule extends the length of seven globular actin molecules. Tm molecule is associated with one tn molecule.