sliding filament theory

Question 1

step 1

Answer 1

Nerve impulse travels down the motor neuron - neuromuscular junction, releasing ACh (acetylcholine). this chemical causes the release of calcium ions

Question 2

step 2

Answer 2

The Calcium binds to troponin (protein), allowing myosin filaments to attach to the actin filaments, forming a “cross-bridge”

Question 3

step 3

Answer 3

ATP is broken down, (into phosphate and diphosphate) 2 allow the myosin 2 pull actin filaments inward 2 shorten the muscle. (thus contraction begins)

Question 4

step 4

Answer 4

Myosin detaches from actin,, .: cross-bridge is broken. When ATP is broken down, myosin can again attach farther down the actin filament (repeating the cycle). Over and over the myosin cross-bridges attach,rotate, detach and attach in rapid succession.

Question 5

step 5

Answer 5

Muscular contraction lasts as long as ATP is available & calcium is present. Once impulse ends, calcium is pumped back into the sarcoplasmic reticulum & actin returns to rest. Muscle lengthens and relaxes