Muscle-relaxing drugs are administered to a patient during major surgery. Which of the two chemicals described next would be a good skeletal muscle relaxant and why? • Chemical A binds to and blocks ACh receptors of muscle cells. • Chemical B floods the muscle cells' cytoplasm with Ca²⁺.

Video transcript

Hi, everyone. Let's look at our next question. Which of the following is not a true statement regarding the action of acetylcholine ach in muscle contraction. So let's go through our answer choices and evaluate each one to see if it's true. Remembering that we are looking for the one that is false choice. A ach is released from motor neurons at the neuromuscular junction and this is a true statement and therefore cannot be our answer choice. B says ach binds to nicotinic acetylcholine receptors and ACH R S on the motor end plete. This is also true. So not our answer as ach is released from the motor neurons that binds to these receptors to says ach causes depolarization of the muscle fiber membrane. Well, this is also true. After it binds to the receptors, you have depolarization of the muscle fiber, meaning you flip the difference in electrochemical charge on the inside and outside of the cell. That's true that happens in the muscle contraction process. So not our answer choice. And now we're down to choice. D ach inhibits the release of calcium ions from the sarcoplasm plasm reticulum. And here, as expected, we have our false answer that we're looking for because ach causes the release of calcium ions not inhibits. So choice D is our correct answer that depolarization causes the calcium ions to be released from the sarcoplasm reticulum. Since we've flipped, the electrochemical uh difference, calcium ions will now be released from the cell and that ends up, they bind to troponin which moves it aside from blocking the min binding site on the acting filament allowing muscle contraction to go forward. So the statement that is not true regarding the action of acetycholine and muscle contraction is choice. D ach inhibits the release of calcium ions from the sarcoplasm reticulum. See you in the next video.