1. Muscles move skeletal parts by contracting
Team 1

2. Contractions
The ability to move requires that the muscles be attached to the skeleton in antagonistic pairs
When bicep contracts, triceps relax- When triceps contract, biceps relax

3. The structure of skeletal muscle
Muscle fiber consists of a bundle of long fibers running parallel to the length of the muscle
Bundle of myofibrils arranged longitudinally

5. Myofibrils Two kinds of myofilaments :
Thin filaments- two strands of actin and one strand of regulatory protein coiled around thick filament
Thick filaments- staggered array of myosin

6. Contractions
In a relaxed muscle fiber, the I bands and the H zone are relatively wide
During contraction, the thick, and thin filaments slide past each other, reducing the width of the I bands and H zone and shortening the sacromere
In a fully contracted muscle fiber, the thin filaments overlap, eliminating the H zone. The I bands disappear as the ends of the thick filaments contract the Z lines

8. Myosin-Actin interactions underlying muscle fiber contraction
See figure 49.30, page 1068 as we explain