Muscle Contractions
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Transcript of Muscle Contractions
Muscle ContractionsFigure 39-4
Sliding Filament Mechanism _________ and_______filaments slide
over each other______________the muscle length
Always requires ________ ions and ___
Actin Double chain of ______
proteins Makes up ____ filament Attached to end walls
of sarcomeres called _____
Makes up __ band of sarcomere
Has ______ binding site which is blocked by ____________ and ____________ in relaxed muscle
Myosin
Makes up _______ filament
Has myosin ________ which bind to _______
Make up ___ bands in a sarcomere
Neuromuscular Junction “Joining” of motor
______ and ___________ _______________-motor
neurons release _________________ that diffuse across synapse to receptors on muscle fiber membrane
Always ______________ Motor unit-
_______branched motor ________ synapsing with ______ muscle _______
11 Steps of a Muscle Contraction
1. An __________________travels down a motor neuron
2. The skeletal muscle _________ is activated at the ____________________ junction
3. An _____________________travels down the muscle __________________________
4. The action potential enters _____________5. An action potential stimulates the
____________________________________
11 Steps of a Muscle Contraction Cont.
6. ______________________are released into the muscle cell ____________________
7. _____________ ions bind to _____________8. ___________________ exposes ___________
binding sites on _________9. Myosin _______ bind to ________10. Myosin heads __________11. _______ filaments are pulled toward
sarcomere center, and muscle fiber ________
Muscle Relaxation
When action potential is over, ________ goes back to _______________________________
Calcium is removed from _____________
Troponin and tropomyosin ________ myosin binding sites
Muscle ____________
1 - Calcium released from sarcoplasmic reticulum 2 - Myosin head energized via myosin-ATPase activity which converts the bound ATP to ADP + Pi 3 - Calcium binds to troponin 4 - Tropomyosin translocates to uncover the cross-bridge binding sites 5 - The energized myosin binding sites approach the binding sites 6 - The first myosin head binds to actin 7 - The bound myosin head releases ADP + Pi, flips and the muscle shortens 8 - The second myosin head binds to actin 9 - The first myosin head binds ATP to allow the actin and myosin to unbind 10 - The second myosin head releases its ADP + Pi, flips & the muscle shortens further 11 - The second myosin head binds to ATP to allow the actin and myosin to unbind 12 - The second myosin head unbinds from the actin, flips back and is ready for the next cycle 13 - The cross-bridge cycle is terminated by the loss of calcium from the troponin 14 - Tropomyosin translocates to cover the cross-bridge binding sites 15 - The calcium returns to the sarcoplasmic reticulum, the muscle relaxes & returns to the resting state
Contraction Clip
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html
http://www.youtube.com/watch?v=EdHzKYDxrKc&feature=player_embedded
http://www.youtube.com/watch?v=gJ309LfHQ3M&feature=player_embedded