Question

select the single word in each sentence to make it correct. 1. excitation - contraction coupling refers to the events that link the action potentials on the sarcolemma to activation of the click to select. it begins with the arrival of the click to select at the neuromuscular junction. 2. next, a wave of action potentials spreads from the end plate in all directions, reaching the t tubules, which carry the excitation wave into the click to select. 3. in the click to select, action potentials open voltage - gated ion channels, whose physical connections cause the release of calcium ions from the terminal cisterns of the sarcoplasmic reticulum into the cytosol. 4. calcium will bind to the click to select of the thin filaments. 5. on the thin filament, active sites are open for the binding of click to select heads, which allows the contraction to begin. t tubules actin action potential myofilaments myosin sarcolemma sarcoplasm tropomyosin troponin

Explanation:

1. Excitation - contraction coupling links sarcolemma action potentials to myofilament activation. It starts with action potential arrival at the neuromuscular junction.
2. Action potential waves spread from the end - plate to T - tubules, carrying the excitation into the sarcoplasm.
3. In the T - tubules, action potentials open voltage - gated ion channels, releasing calcium from the sarcoplasmic reticulum into the cytosol.
4. Calcium binds to troponin on thin filaments.
5. On thin filaments, active sites open for myosin head binding to start contraction.

Answer:

1. myofilaments, action potential
2. sarcoplasm
3. T tubules
4. troponin
5. myosin