Sliding Filament Theory Video Part 2 NSCA Certification
Sliding Filament Theory Video Outline Part 2
14. 5 Phases of the Sliding Filament Theory of Muscular Contraction
- Resting Phase
- Excitation-Contraction Coupling Phase
- Contraction Phase
- Recharge Phase
- Relaxation Phase
*Remember-there are 5 phases
15. 1. Resting Phase
- The muscle is not being stimulated by the motor neuron so the muscle is at rest.
Sliding Filament Theory Video Part 1 NSCA Certification
Sliding Filament Theory Video Outline Part 1
1. Sliding Filament Theory of Muscular Contraction (Intro)
2. Muscular Contraction
- Muscle fibers contract by a shortening of their myofibrils due to actin filaments sliding inward over myosin filaments which causes the muscle to shorten and develop tension.
3. During Muscular Contraction
- Z-lines are pulled toward the center of the sarcomere
- H-zone shrinks
- I-Band shrinks
- A-Band remains the same length
Myofibril Blank Study Guide NSCA Certification
To help you learn more about myofibrils, I prepared a blank myofibril study guide. You can print this out and label the diagram with the keywords listed below.
Myofibril Diagrams NSCA Certification
Below are three diagrams I made to help you understand myofibrils and the sliding filament theory of muscle contraction . The images are listed in the following order:
- Myofibril-Relaxed Muscle
- Myofibril-Contracting Muscle
- Myofibril-Fully Contracted Muscle
Click on the images if you want to make them larger.
I also made a pdf document that you can download here: Myofibril-Muscle Contraction NSCA CSCS Exam.pdf (click link to download).
Chap. 1 Muscular System-Sliding Filament Theory of Muscular Contraction NSCA Certification
Muscle fibers contract by a shortening of their myofibrils due to actin filaments sliding inward over myosin filaments.
During Muscular Contraction:
- Z-lines are pulled toward the center of the sarcomere
- H-zone shrinks
- I-Band shrinks
- A-Band remains the same length
5 Phases of the Sliding Filament Theory of Muscular Contraction
1. Resting Phase-The muscle is not being stimulated by the motor neuron so the muscle is at rest.
2. Excitation-Contraction Coupling Phase
- Calcium is released into the myofibril.
- Calcium attaches to troponin, which causes the shifting of tropomyosin and exposing the active binding sites on the actin molecule.
- Myosin cross-bridge heads attach (coupling) to actin filaments.
3. Contraction Phase
Myosin cross-bridges flex by using the energy released by the breakdown of ATP
* ATP is needed for myosin cross-bridge flexion
* Another ATP is needed for the myosin to detach from actin and recock.
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