Muscle contraction is a process leading to the shortening and or development of tension in muscle tissue. Tension is developed in muscle tissue when muscles contract. That tension may or may not lead to movement. To contract means to shorten; however, this is not always the case in a muscle contraction. The tension may cause muscle to remain the same, elongate, or condense. When muscles decrease in length (e.x. lifting weights) it is called a concentric contraction. When muscles increase in length (e.x. doing pushups) it is called an eccentric reaction. There are two proteins responsible for muscle contractions: Actin and Myosin. The interaction of Actin filaments gliding over Myosin filaments is what causes the shape change in muscle cells.
The physical process of muscles contracting happens rapidly. …show more content…
The brain or spinal cord sends an action potential to the muscle.
2. The impulse travels down the motor neuron and reaches a neuromuscular junction where it releases acetylcholine, which triggers the action potential in the muscle.
3. The action potential travels through the sarcolemma and down the T-tubules surrounding the myofibrils.
4. As the impulse passes through the T-tubules, it causes the Sarcoplasmic Reticulum surrounding the T-tubule to release Calcium ions into the sarcoplasm, eventually reaching the sarcomere.
5. The Calcium binds to troponin located on the actin filament, causing the tropomyosin to move and expose binding sites for myosin.
6. The myosin head now binds to actin and forms a crossbridge.
7. ADP and Pi are released from myosin, which causes the myosin to move. This movement is called the power stroke.
8. ATP binds to myosin causing it to release the actin and reverting ATP into ADP and Pi. The myosin is now ready to form another crossbridge and the cycle of contraction will continue until the impulse stops.
9. Once the impulse stops, Calcium is released from troponin causing tropomyosin to cover the binding sites and prevent
The physical process of muscles contracting happens rapidly. …show more content…
The brain or spinal cord sends an action potential to the muscle.
2. The impulse travels down the motor neuron and reaches a neuromuscular junction where it releases acetylcholine, which triggers the action potential in the muscle.
3. The action potential travels through the sarcolemma and down the T-tubules surrounding the myofibrils.
4. As the impulse passes through the T-tubules, it causes the Sarcoplasmic Reticulum surrounding the T-tubule to release Calcium ions into the sarcoplasm, eventually reaching the sarcomere.
5. The Calcium binds to troponin located on the actin filament, causing the tropomyosin to move and expose binding sites for myosin.
6. The myosin head now binds to actin and forms a crossbridge.
7. ADP and Pi are released from myosin, which causes the myosin to move. This movement is called the power stroke.
8. ATP binds to myosin causing it to release the actin and reverting ATP into ADP and Pi. The myosin is now ready to form another crossbridge and the cycle of contraction will continue until the impulse stops.
9. Once the impulse stops, Calcium is released from troponin causing tropomyosin to cover the binding sites and prevent