Guided reading questions Action potential Please note the page numbers might be slightly different between the eText and the printed version Use the titles subtitles mentioned below to locate the specific text Read page 287 Section 11 3 3 Action Potentials up to and not including The Refractory period Also watch the animation here https www youtube com watch v kxnb TSqmFY Do not hesitate to use the web when a question is not specifically addressed in the textbook 1 The major type of ion channels that trigger an action potential are the voltage gated channels 2 The trigger zone the site where the action potential initiates is found at the axon hillock 3 Voltage gated channels will open up when the membrane potential reaches a threshold of 4 Only Na voltage gated channels respond to a membrane potential of 55mV 55 mV a True b False the correct choice feedback loop work 5 Opening of the sodium activation gates lead to a flow of Na into out of the cell circle 6 The author mentions a positive feedback loop on step 2 How does the positive The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input the sodium channel opening causing depolarization amplifies the output further depolarization with more sodium entering the cell The initial input amplifies the output as in the initial depolarization leads to more sodium ions entering the cell and thus more depolarization 7 The membrane potential does not go beyond 30mV due the closing of the voltage gated sodium gate 8 Repolarization step 3 is caused by the complete opening of the potassium channels 8 During repolarization K flow into out of the cell circle the correct choice 9 How do you explain the fact that the membrane potential drops below the original resting membrane potential aka the hyperpolarization step step 5 As potassium leaves the cell and induces repolarization the gates themselves are actually quite slow to close As such even as the gates close when the membrane potential reaches 70 mV some cells will still leave the cell Once the gates are fully closed however the sodium potassium pumps restore the resting membrane potential 10 Upon closing of the K gated channels Na and K concentrations in the ICF and the ECF are similar to the original concentrations prior to the initiation of the action potential a True b False