Figure 1 shows a schematic of an action potential. How do voltage-gated sodium channels contribute to stages 1, 3 and 6? In your answer, state what happens to the activation and inactivation gates at these three stages. Membrane Potential (mv) 50 0 -50 -100 6² 1 T 0 1 2 3 Time (milliseconds) 4 5 5 6 7

Figure 1 shows a schematic of an action potential. How do voltage-gated sodium channels contribute to stages 1, 3 and 6? In your answer, state what happens to the activation and inactivation gates at these three stages. Membrane Potential (mv) 50 0 -50 -100 6² 1 T 0 1 2 3 Time (milliseconds) 4 5 5 6 7

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section4.1: Introduction To Neural Communication

Problem 2CYU

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Figure 35.11 Potassium channel blockers, such as amiodarone and procainamide, which are used to treat abnormal electrical activity in the heart, called cardiac dysrhythmia, impede the movement of K+ through voltage-gated K+ channels. Which part of the action potential would you expect potassium channels to affect?
Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)
1. Which of the following is the rapid upstroke in the action potential? A. Phase 0 B. Phase 1 C. Phase 2 D. Phase 3
Action potentials occur when ______. a. potassium gates close b. a stimulus pushes membrane potential to threshold c. sodium-potassium pumps become active d. neurotransmitter is reabsorbed
In an experiment, the extracellular [Na+] surrounding a nerve cell was reduced from 145 to 45 mM. Which of the following is the most likely effect of this on action potentials? No action potentials would occur because the concentration of extracellular Na+ is too low. The membrane potential would become more negative so the threshold for action potential generation could not be reached. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarisation phase would be slower. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarization phase would be more rapid.
Can you explain to me why choice E is the correct answer and break down why the other options are false?Select the choice option that is TRUE regarding the absolute and relative refractory periods of the action potential (AP). A. The absolute refractory period occurs when the activation gate of voltage gated sodium channel closes at the peak of the AP B. The relative refractory period occurs when the inactivation gate of voltage gated sodium channels closes at the peak of the AP C. The relative refractory period occurs when the activation gate of voltage gated potassium channels opens at the peak of the AP D. The absolute refractory period may be overcome if enough excitatory stimulation is applied to the neuronal membrane E. All of the choice options are FALSE regarding the absolute and relative refractory periods of the AP
Diagram an Action potential: an action potential graph showing the 4 steps of an action potential AND what is happening to the sodium voltage-gated channels and voltage-gated potassium channels at each step
At which point in the graph do voltage-gated potassium channels open? (Base your answer to this question on the graph below depicting an action potential.) A B C D E
Dendrotoxins, produced by the mamba snakes (Dendroaspis), are inhibitors of the voltage-gated K+ channels. What phase of the action potential would this toxin affect? How would it affect ion permeability during this phase? How would ion movement be affected?
You find a neuron whose resting potential is -90mV. Which of the following are likely to be true? (select all that apply) Voltage-gated sodium channels are closed The neuron is fully permeable to sodium The neuron is permeable to potassium The neuron is hyperpolarized
Based upon the changes in permeability seen in the trace below and your knowledge of ion distributions across a cell, predict how ion movements would change during an action potential. Drag and drop each phrase into the appropriate box on the action potential trace. Drag the appropriate labels to their respective targets. Note: not all labels will be used. ►View Available Hint(s) Sodium (Na+) ions move to the axon Sodium (Na) ions move out of the axon Less potassium (K) ions move out of the axon Potassium (K) ions move out of the axon Potassium (K¹) ions move into the axon Sodium (Na) ions stop moving in Membrane potential (mv) +30 +10 0 -10- -30 -50 -70 -90 A PNa 0 PNa 5 6 1 PK Threshold PK 2 Reset Help
Describe the events that occur during action potential ANSWER SHOULD INCLUDE: Explanation of how resting membrane potential works and which ions inside/outside Expiation of how depolarisation membrane occurs and which ions move in/how they move in . Explanation of "threshold" . Explanation of depolarisation and which ions move out and how they move out. Explanation of hyperpoarisation and how it is corrected. ( state membrane potential in mv during each stage )