Please briefly provide the 3 steps in the sliding filament model of muscle contraction.?
Describe how actin and myosin cause muscles to contract.
- Anonymous1 decade agoFavorite Answer
1. Distal end of motor neuron releases acetylcholine (ACh)
2. ACh diffuses across the gap at the neuromuscular junction (synaptic cleft)
3. Muscle fiber membrane stimulated. Muscle impulse travels through transverse tubules. Reaches sarcoplasmic reticulum (SR)
4. Ca++ diffuse from SR to bind on troponin
5.Troponin and tropomyosin exposes binding site on actin
6. Actin + myosin filaments form links
7. Myosin cross-bridge pull actin filament inwards
8. Muscle fiber shortens
(Greater detail of steps 7-8 above)
myosin head at 45 degrees relative to actin. Mysosin tightly bound to an actin (in rigor state)
ATP binds to binding site on myosin. Myosin detaches actin.
Myosin ATPase actively hydrolyzes ATP which remains bound to myosin
Energy is used to swing myosin head over and bind weakly to new actin molecule. Cross bridge is now 90 degrees relative to filament (relaxed state)
Release of Pi initiates power stroke. Myosin pushes actin filaments past it returning the myosin head to the 45 degree position
myosin head releases ADP and resume the rigor state
- bleimehlLv 44 years ago
while the muscle gets the sign calcium is released which reason differences in troponin and tropomysin to circulate off the lively internet site on the thin filaments. ATP binds to the top on the leg of thick filament which reasons it to snatch the lively internet site on the thin filament inflicting a circulate bridge. ATP is then hydrolyzed and the leg contracts pulling the thin fillament inward.