Neurophysiology 2

1. 1The inactivation gate for sodium channels can be removed by infusions of scorpion venom or proteolytic enzymes inside the myelinated axon. Once the inactivation gate is removed, which characteristic of the axon potential should change most noticeably?

   1. AThe action potential duration should be decreased
   2. BThe magnitude of the afterhyperpolarizatoin that follows the action potential should be greater
   3. CThe peak amplitude of the action potential should be reduced
   4. DThe rate of the repolarizing phase of the action potential should be decreased
   5. EThe rate of the depolarizing phase of the action potential should be decreased
2. 2At what phase is K+ permeability 20 times higher than Na+ permeability?

   

   1. A1
   2. B4
   3. C5
   4. D8
3. 3At what phase is the largest number of voltage-gated K+ channels open?

   

   1. A3
   2. B4
   3. C5
   4. D7
4. 4At what phase is the ratio of the open to inactivated Na+ channels the greatest?

   

   1. A1
   2. B2
   3. C3
   4. D4
5. 5At what phase (or phases) is closest to the K+ equilibrium potential?

   

   1. A4
   2. B5
   3. C7
   4. D8
6. 6At what phase is the Na+, K- ATPase active?

   

   1. A1
   2. B2
   3. C3
   4. D4
   5. E5
   6. F6
   7. G7
   8. H8
7. 7At what phase can the pulse grow more positive than the Na+ equilibrium potential?

   

   1. ANone
   2. B1
   3. C4
   4. D7
   5. E8
8. 8At what phase is Na+ driven into the cell by its ionic gradient but not by membrane potential?

   

   1. A4
   2. B5
   3. C7
   4. D3
9. 9At what phase is Na+ is driven into the cell by both ionic gradient and membrane potential?

   

   1. A1 to 3, 6 to 8
   2. B1 to 2, 7 to 8
   3. C1 to 4, 5 to 8
   4. D1 to 8
10. 10In what phase is Na+ driven into the cell by membrane potential but not by ionic gradient?

    

    1. ANone
    2. B1
    3. C2
    4. D6
    5. E8

11. 11In what phase is K+ ion pulled into the cell by both membrane potential and ionic gradient?

    

    1. ANone
    2. B3
    3. C4
    4. D1
    5. E8
12. 12At what phase can no new action potential be triggered even if strongly stimulated?

    

    1. A2
    2. B3
    3. C4
    4. D5
    5. E6
    6. F7
    7. G8
    8. H1
13. 13The AP propagation relies on local diffusion of Na+ within the axoplasm, so it is slow

    1. ATrue
    2. BFalse
14. 14To speed up AP propagation, the axonal diameter should be small

    1. ATrue
    2. BFalse
15. 15The key properties of VNA channels dictating AP signature properties are

    1. Athey have two gates
    2. Bthe activation gate opens at potentials above -50 mV
    3. Cwhen the activation gate is open, conformational change subsequently induces the closing of inactivation gate within 2 msec
16. 16Action potentials signature properties are

    1. Aactivation threshold
    2. Bself-regenerative depolarization
    3. Call-or-none response
    4. Drefractory period
17. 17The larger the membrane depolarization, the more VNa's open the activation gate

    1. ATrue
    2. BFalse
18. 18The activation gate stays open as long as the MP is above -50mV

    1. ATrue
    2. BFalse
19. 19What is true in relation to the VNa's channels and membrane potential?

    1. AAt -50 mV activation gate begins to open in 5% of of VNa
    2. BAt -30 mV half of the channels are open
    3. Cat +10 mV all the channels are open
20. 20At resting potential, the inactivation gate is closes while the activation gate is open.

    1. ATrue
    2. BFalse
21. 21The opening of the activation gate

    1. Ainduces the closing of the inactivation gate
    2. Binduces the opening of the inactivation gate
    3. Chelps make action potential very transient for the health of the brain
    4. Dopens above -50 mV
22. 22During febrile seizures

    1. Athe activation gate is closing slower than normal
    2. Baction potential is increasing in duration
    3. Cglutamate release is increasing, excessively activating the post-synaptic neurons.
    4. Dexcitotoxicity by glutamate
23. 23Delayed rectifier K+ channels are characterized by

    1. AAP repolarization
    2. Bproduction of afterhyperpolarization
    3. Cproduction of a relative refractory period
    4. DAP depolarization
24. 24Voltage-gated delayed rectifier K+ channels

    1. Ahave only the activation gate
    2. Bopen when the membrane potential is above -30 mV
    3. Chas an opening rate a few msec slower than VNa+ channels
    4. Dall of the above
25. 25DRK contributes to absolute refractory period and also produces relative refractory period.

    1. ATrue
    2. BFalse
26. 26Delayed rectifier K+ channels

    1. Acontribute to absolute refractory period
    2. Bproduce relative refractory period.
    3. Copen to counteract membrane depolarization by synaptic input
27. 27In the absolute refractory period, the open Na+ channels are undergoing activation

    1. ATrue
    2. BFalse
28. 28In relations to membrane potential, hyper polarized means

    1. Amore positive than the baseline
    2. Bmore negative than the baseline
    3. Cactivation
29. 29If you doubled the synaptic input to a neuron, what would happen to the action potential generated?

    1. ANothing
    2. BIt would increase in amplitude
    3. CIt would increase in duration
    4. DIt would decrease in amplitude
30. 30Unmyelinated axons

    1. Aare fast
    2. Bare slow
    3. Ccause large ATP consumption
    4. Dare leaky
31. 31Myelinated axons

    1. Aare wrapped by segments of glial membranes
    2. Bhave a lipid-rich myelin sheath
    3. Care exposed
    4. Dare fast
32. 32A stimulating electrode is places at the midpoint along the length of the axon. The electrical stimulation produces an action potential at this location. This action potential will:

    1. Apropagate only distally toward the axon terminal
    2. Bpropagate only proximally toward the soma
    3. Cpropagate bidirectionally toward both the axon terminal and soma
    4. Dpropagate in neither direction
33. 33In some individuals with certain genetic abnormalities, extracellular K+ falls markedly when epinephrine or insulin stimulates its uptake by muscle cells. This
    

    1. Ais due to decrease in extracellular K+, which will hyper polarize the membrane potential of the muscles making AP generation more difficult in the muscles.
    2. Bcauses weakness or paralysis in the muscles
    3. Cleads to hypokalemic periodic paralysis
    4. Dall of the above
34. 34Which of the following is NOT a correct property of an action potential?

    1. Aself-degenerative depolarization
    2. Bactivation threshold
    3. Crefractory period
    4. Dall-or-none production
35. 35When the membrane is depolarized by synaptic input to ~-50 mV, the activation gates of about 5% of the VNa channels begin to open. This is critical to start

    1. Aself-regenerative depolarization
    2. Baction potentials
    3. Call-or-none production
    4. Dhyperpolarization
36. 36Epilepsy, multiple sclerosis, and sensory motor disorders can arise due to spatial temporal disarrays in ________________.

    1. Aaction potential generation
    2. Bneurotransmitter inhibition
    3. Caction potential propagation
    4. Dneurotransmitter regulation
37. 37The membrane has to depolarize (become less negative) if an action potential is to be generated. This describes which property?

    1. Aself-regenerative depolarization
    2. Bactivation threshold
    3. Call-or-none production
    4. Dabsolute refractory period
38. 38The inactivation gate is open. What happens next?

    1. AThe membrane depolarizes
    2. Bconformational change induces opening of the activation gate
    3. Cit remains open until another AP fires
    4. DThe conformational change induces closing of the inactivation gate
39. 39When does the activation gate of the VNa channel open?

    1. Awhen the membrane potential reaches -70 mV
    2. Bwhen the membrane potential reaches -50 mV
    3. Cwhen it is bound by K+ ions
    4. Dwhen the inactivation gate closes
40. 40Which of the following below is NOT a role of the delayed rectifier potassium channel?

    1. Aproduce relative refractory period
    2. Bopening and closing of both inactivation and activation gates
    3. Caction potential depolarization
    4. Dproduce afterhyperpolarization
41. 41At resting membrane potential, what is true regarding the two gates of VNa channels?

    1. AThe activation gate is open and the inactivation gate is open
    2. BThe activation gate is closed and the inactivation gate is closed
    3. CThe activation gate is open and the inactivation gate is closed
    4. Dthe activation gate is closed and the inactivation gate is open
42. 42An action potential has finished generating. When is the earliest another action potential could fire?

    1. AAbout 2-5 msec after the first action potential
    2. BImmediately after the first action potential if the AP propagates in both directions along the axon
    3. CImmediately after the first action potential if sufficient synaptic input occurs
    4. DAbout 200-500 msec after the first action potential

Description

physiology Quiz on Neurophysiology 2, created by Pretoria Okafor on 12/06/2020.

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Pretoria Okafor

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