The Musculoskeletal System
Muscle Contraction and Locomotion
Muscles are responsible for locomotion, the contractions of internal organs, and the contractions of the heart.
Skeletal Muscle Fiber Structure
Skeletal muscles are composed of striated subunits called sarcomeres, which are composed of the myofilaments actin and myosin.
Sliding Filament Model of Contraction
In the sliding filament model, the thick and thin filaments past each other, shortening the sarcomere.
ATP and Muscle Contraction
ATP is critical for muscle contractions because it breaks the myosin-actin cross-bridge, freeing the myosin for the next contraction.
Tropomyosin and troponin prevent myosin from binding to actin while the muscle is in a resting state.
Excitation–contraction coupling is the connection between the electrical action potential and the mechanical muscle contraction.
Control of Muscle Tension
Muscle tension is influenced by the number of cross-bridges that can be formed.