Fill in the blank using information available from the diagram above: With every action potential sarcoplasm. More calcium in sarcoplasm means tropomyosin active site of (more/less) calcium is dumped into the cytoplasm or (can/cannot) cover the (actin/myosin) and as a result, there will be (more/less) interaction between actin and myosin. Calcium ATPase will take (longer/shorter) to remove calcium from the sarcoplasm and re-sequester them back into the sarcoplasmic reticulum. If another action potential arise before calcium has been re-sequestered into the sarcoplasmic reticulum, that means even (more/less) is in the sarcoplasm. (more/less) contraction. Eventually these contractions will (more/less) calcium means lead to fused tetanus that means the entire muscle cannot contract any more. It has reached maximum contraction.

Various steps during the contraction of a muscle fiber include-

- Arrival of a nerve impulse to a neuromuscular junction on a muscle cell. At a neuromuscular junction, an axon of the neuron meets a muscle cell.

- Acetylcholine is released from the axon of the neuron and binds to the receptors present on the sarcolemma.

- Depolarization of the sarcolemma by the opening of the Na+ ion channels and thereby allowing more and more Na⁺ ions inside the muscle cell.

- Na⁺ ions diffuse into the muscle fiber and depolarization occurs.

- The action potential travels deep down to the T-tubule and triggers the sarcoplasmic reticulum to release Ca⁺² into the sarcoplasm.

- As the Ca⁺² level increases, these bind to the Troponin which further removes the blocking action of Tropomyosin from the actin-binding sites.

- Myosin now binds to the actin filament thereby forming a cross-bridge that begins the contraction process.

-For the contraction process, the ATP binds to the myosin filament.

- ATP is then hydrolyzed to ADP and Pi that provides the myosin required energy to cock its head to the high-energy position.

- Actin and myosin bind together to form a cross bridge.

-The myosin head then pulls the actin filaments inward and releases the ADP and Pi and returns to a low-energy position.