Mr Rush Outcome #9 (Describe the major events that occur when a muscle fiber contracts)

Not completely understood

Step #1

Motor neuron releases neurotransmitter causing a muscle impulse and releases calcium ions.

Step #2

Calcium binds to troponin causing it to move tropomyosin away from binding sites on actin filament.

Step #3

Myosin cross-bridges attach to actin filaments

Step #4

Cross-bridges pull actin inward by bending

Step #5