How it is applied: In muscle contraction, ATP must be released in order for a myosin head to bind with an actin myofilament . ATPase breaks down ATP in order for the muscle contraction to occur leaving two phosphate atoms instead of three. When ATPase breaks down ATP into ADP + P, it is hydrolyzed.

1. ACh is released at the terminal end of a motor neuron and diffuses across the synaptic gap
2. The Sarcolemma is stimulated causing Calcium ions to diffuse into the sarcoplasm
3. Calcium binds to troponin and moves tropomyosin to allow myosin heads to link with actin
4. Myosin cross bridges pull actin filaments inward
5. Muscle shortens as a contraction occurs
6. ACh is broken down by acetocholinerase which stops muscle fiber stimulation causing calcium to be reabsorbed into the sarcoplasmic reticulum
7. Actin and myosin break and slide apart
8. ATP is released/used to release the cross bridge to end muscle contraction

How it is controlled: In order for muscle contraction to occur, the neurotransmitter acedylcholine must be sent and bound to the receptor sites. This allows calcium ions to be diffused through the sarcoplasmic reticulum setting off the steps of muscle contraction.

Works Cited

• https://www.merriam-webster.com/dictionary/ATPase
• http://www.ptprogress.com/muscle-contraction-steps-review/
• http://www.tutorvista.com/content/biology/biology-iv/locomotion-animals/muscular-contraction.php
• http://muscle.ucsd.edu/musintro/histochem.shtml