1. Muscles & Motion

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

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

5. Neuromuscular Junctions CNS sends action potential down motor neuron CNS sends action potential down motor neuron Synaptic Vesicles release Ach (acetylcholine) Synaptic Vesicles release Ach (acetylcholine) Ach diffuses across synapse Ach diffuses across synapse Ach binds to membrane receptors triggers action potential that spreads through muscle fiber along T-tubules Ach binds to membrane receptors triggers action potential that spreads through muscle fiber along T-tubules T-tubules are in-foldings of cell membrane T-tubules are in-foldings of cell membrane (signaling molecule/ cell communication essay topic) (signaling molecule/ cell communication essay topic) http://www.dnatube.com/video/1950/Molecular-events-in-muscle-contraction http://www.dnatube.com/video/1950/Molecular-events-in-muscle-contraction http://www.dnatube.com/video/1950/Molecular-events-in-muscle-contraction http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0010-swf_action_potenti.swf http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0010-swf_action_potenti.swf http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0010-swf_action_potenti.swf

7. Sarcoplasmic Reticulum (SR) Action Potentia in T-tubule activates SR http://www.sumanasinc.com/webcontent/animations/content/muscle.html Action Potentia in T-tubule activates SR http://www.sumanasinc.com/webcontent/animations/content/muscle.html http://www.sumanasinc.com/webcontent/animations/content/muscle.html 1. SR releases Ca + into muscle fiber 1. SR releases Ca + into muscle fiber 2. Ca + binds to 2. Ca + binds to Troponin Troponin 3. Troponin moves 3. Troponin moves Tropomyosin Tropomyosin 4. Muscle contracts 4. Muscle contracts http://www.youtube.com/watch?v=XoP1diaXVCI http://www.youtube.com/watch?v=XoP1diaXVCI http://www.youtube.com/watch?v=XoP1diaXVCI

8. Lack of Action Potential Sarcoplasmic Reticulum actively uptakes Ca + Sarcoplasmic Reticulum actively uptakes Ca + Low Ca + levels in muscle fiber makes Low Ca + levels in muscle fiber makes Tropomyosin block myosin binding sites Tropomyosin block myosin binding sites Sarcomeres relax Sarcomeres relax

9. End Here 2014

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

15. Myosin heads primed by ATP

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

18. Myosin releases ADP and P and bends toward center of sarcomere Myosin releases ADP and P and bends toward center of sarcomere Actin pulled toward center Actin pulled toward center ATP binds myosin & resets myosin head ATP binds myosin & resets myosin head http://www.dnatube.com/video/1306/Role -of-myosin-crossbridge-in-the-contraction- of-muscle http://www.dnatube.com/video/1306/Role -of-myosin-crossbridge-in-the-contraction- of-muscle http://www.dnatube.com/video/1306/Role -of-myosin-crossbridge-in-the-contraction- of-muscle http://www.dnatube.com/video/1306/Role -of-myosin-crossbridge-in-the-contraction- of-muscle