1. Muscles & Motion

2. Evolution of Movement 1) epitheliomuscular cells in Cnidarians
epithelial cells w/ contractile protein arrays
(actin & myosin)
2) epitheliomuscular
cells sank below
surface into
connective tissues
and became muscle

3. Bundles of muscle cells fuse together inside a covering of connective tissue
Bundles of fused muscle cells form muiltinucleate muscel fibers
The connective tissue covering extend past the muscle fibers to attach to bones

9. Regulatory Proteins Tropomyosin – blocks myosin binding sites on actin
Troponin complex – move tropomyosin out of the way so myosin can bind to the actin ….activated by Ca

10. Myosin heads primed by ATP

11. Binding site blocked by tropomyocin
Ca bonding to troponin Δ its shape
Δ troponin moves tropomyocin out of
binding site
Myosin binds
to actin

13. Myosin releases ADP and P and bends toward center of sarcomere
Actin pulled toward center
ATP binds myosin & resets myosin head

16. Neuromuscular Junctions
CNS sends action potential down motor N
Synaptic Vs release Ach (acetylcholine)
Ach diffuses across synapse
Ach binds to membrane receptors triggers action potential that spreads through muscle fiber along T-tubules
T-tubules are infoldings of cell membrane

18. Sarcoplasmic Reticulum (SR)
Action Potentia in T-tubule activates SR
1. SR releases Ca into muscle fiber
2. Ca binds to
Troponin
3. Troponin moves
Tropomyosin
4. Muscle contracts

19. Lack of Action Potential
Sarcoplasmic Reticulum pumps Ca back in
Low Ca levels in muscle fiber
Tropomyosin blocks myosin binding sites on actin.
Sarcomeres relax