Why do voltage-gated sodium channels have three states (open, closed, refractory/open-block)? Select all that apply. i Multiple answers: Multiple answers are accepted for this question Select one or more answers and submit. For keyboard navigation... SHOW MORE ✓ a b с d To keep action potentials from going backwards To speed up the refractory period To prevent the channels from opening during repolarization To allow hyperpolarization to occur Answered Resubmit

Why do voltage-gated sodium channels have three states (open, closed, refractory/open-block)? Select all that apply. i Multiple answers: Multiple answers are accepted for this question Select one or more answers and submit. For keyboard navigation... SHOW MORE ✓ a b с d To keep action potentials from going backwards To speed up the refractory period To prevent the channels from opening during repolarization To allow hyperpolarization to occur Answered Resubmit

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

Section: Chapter Questions

Problem 1RE: Conformational changes in channel proteins brought about by voltage changes are responsible for...

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Epilepsy is a condition which results in seizures stemming from excessive or abnormal activity of neurons. This can occur either from hyperexcitability of excitatory neurons, or impairment of inhibitory neurons. That is to say, either the excitatory pathways become overactive, or the inhibitory pathways, designed to temper the excitatory pathways, are not active enough. Much of the research done on epilepsy focuses on voltage-gated sodium channels, and to date over 700 different mutations to the channel have been identified as playing a role in epilepsy. The means by which these mutations contribute to epilepsy is quite complex, but for the sake of this CAL, let's simplify and apply what we have learned so far to identify potential mechanisms for this condition. In what way could voltage-gated sodium channels be affected in excitatory neurons which would increase the likelihood of the neuron firing an action potential? (one correct answer) The inactivation gate is slower to close. The…
Describe the action potential in terms of the different functional states of the voltage- gated Na+ membrane channels (Note: there are three states)
The action potential is split into 4 parts (A-D). For each part, 1. Describe what stimulated the channel responsible for this part, 2. what is the likely ion that is moving and 3. explain which direction the ion had to move to create the measured membrane potential.
In the figure to the left, name the 4 phases of the action potential (Note: you have to write in where phase 4 occurs). Describe what happens in each phase with a focus on Na+ and K+ flow through channels and the membrane potential. Discuss the importance of threshold. How does this relate to the concept of APs being all or none?
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
Draw a typical action potential (correctly label axis) and explain in words the roles of ion channels in generating the different phases of the action potential. (Extra credit: How would opening voltage gated calcium channels upon depolarization affect the shape of the action potential if they have a relatively slow inactivation rate?)
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
State whether the channels listed would be open or closed at the corresponding numbered phases of the action potential graph. Phase on Graph Sodium Voltage Gated channels Potassium Voltage Gated channels 1 2 3 4
-60mV -90mV -70mk Refer to the figure of 3 action potentials. The spike height of this/these action potential(s) would depend on the concentration of extracellular sodium. A and B A only B only C only B and C
A graded potential that achieves threshold leads to the generation of an action potential. Which one of the following statement/s regarding graded and action potentials is/are true? O graded potentials result from the opening of chemically gated sodium channels O action potentials result from the opening of voltage gated sodium channels O graded potentials result from the opening of calcium gated channels and action potentials result from the opening of sodium gated channels a and b Next
Each of the following is a correct relationship between action potential phase and channel status except Select one: O A. hyperpolarizing phase; Na channels open O B. repolarizing phase; K channels open O C. depolarization; Na channels open O D. hyperpolarizing phase; K channels open O E. repolarizing phase; Na channels closed
Membrane Potential (mV) +35 0 -50 -70 0 A B C | 2 Time (milliseconds) 3 E 4 Use the figure showing phases of the action potential to answer the following question. Most of the voltage-gated sodium channels become open at label ____, and become inactivated at label