Review Note

Describe the process of muscle contraction 
1. {{c1::Motor signal generation: Motor action potential generated, arrives at neuromuscular junction}}
2. {{c1::ACh released from neuron, opens sodium ion channels → AP in sarcolemma}}
3. {{c1::Ca²⁺ binds to troponin, causing a conformational change that moves tropomyosin away from the binding sites on actin filaments}}
4. {{c1::Cross-Bridge Formation: Myosin heads, energized by ATP hydrolysis, attach to the exposed binding sites on actin, forming cross-bridges}}
5. {{c1::Power Stroke: The myosin heads pivot, pulling the actin filaments toward the center of the sarcomere, which shortens the muscle fiber (contraction).}}
6. {{c1::A new ATP binds to myosin releasing it from actin.}}
7. {{c1::Repeat 3-6 as long as ATP and Ca²⁺ available.}}