Energy Released

Question 1

Resting State

Answer 1

• there are few or no electrical impulses reaching the muscles
• there are Ca2+ions within sarcoplasmic reticulum
• ATP is stored, not broken down

Question 2

During contraction

Answer 2

• nerve impulses travel along axons to axon end plate
• acetylcholine travels across the synaptic cleft to myofibril
• sarcoplasmic reticulum releases Ca2+
• myosin cross-bridges attach to actin
• ATP is broken down and energy is released

Question 3

On relaxation

Answer 3

• the nerve impulses stop
• Ca2+ions are taken up by sarcoplasmic reticulum
• myosin cross bridges are broken down
• the muscle relaxes