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Muscle Cell
Steps
Question | Answer |
---|---|
Muscle Cell is at rest, the SR are pumping calcium ions into sacs | Step 1 |
The motor neuron signals the release of acetylcholine (ACH) into the neuromuscular junction (synaptic cleft) | Step 2 |
ACh stimulates the receptors on the sarcolemma and initiates the electrical impulse | Step 3 |
The nerve impulse travels along the sarcolemma and down the T-tubules | Step 4 |
The impulse triggers the release of calcium into the sarcoplasm | Step 5 |
Calcium binds to troponin (which is the protein that holds the protein tropmyosin in place over activ=ns binding site) | Step 6 |
Tropomyosin shifts exposing the active site on actin | Step 7 |
The head of myosin (energized by ATP) binds to actin (cross-bridge) abd pulls the thin filament (attach to Zplates of sacromere) past them (power stroke) | Step 8 |
In the presence of ATP, each myosin head releases actin and then binds to the next active site (muscle fiber shorten/contract as think and thin filaments slide past eachother) | Step 9 |
The sarcoplasmic reticulum starts actively pumping calcium ions back into the storage sacs. | Step 10 |
As calcium is removed from troponin, this allows tropomyosin to again block the active sites on actin and the muscle relaxes | Step 11 |