Action Potentials

1. 1What is the equilibrium potential of an ion?

   1. AThe membrane voltage a cell needs to prevent movement of that ion down its concentration gradient
   2. BThe membrane voltage a cell needs to prevent movement of that ion against its concentration gradient
   3. CThe membrane voltage a cell needs to open that ions voltage-gated channel proteins
   4. DThe amount of that ion required to initiate an action potential
2. 2When an ion moves down its electrochemical gradient, the membrane potential moves towards that ion's equilibrium potential.

   1. AVerdadero
   2. BFalso
3. 3What is the correct equation for the driving force of an ion?

   1. AMembrane potential - equilibrium potential
   2. BEquilibrium potential - membrane potential
   3. CMembrane potential + equilibrium potential
   4. DEquilibrium potential x membrane potential
4. 4Fill in the blanks below to describe how driving force works in terms of sodium and potassium ions.
   The resting membrane potential is [blank_start]-70[blank_end]mV.
   The equilibrium potential of a potassium ion is [blank_start]-90[blank_end]mV.
   Therefore, the driving force of a potassium ion must be [blank_start]+20[blank_end]mV.
   This [blank_start]positive[blank_end] driving force means that potassium is moved out of the cell.
   The equilibrium potential of a sodium ion is [blank_start]+50[blank_end]mV.
   This means that the driving force of a sodium ion is [blank_start]-120[blank_end]mV.
   The [blank_start]negative[blank_end] driving force means that sodium is moved into the cell.

   1. A-70
   2. B-90
   3. C+20
   4. D+50
   5. Epositive
   6. F-120
   7. Gnegative
5. 5Why is the membrane more permeable to potassium than sodium at rest in order to maintain potential?

   1. ASodium has a greater driving force on it
   2. BPotassium has a greater driving force on it
   3. CBecause potassium can diffuse across the lipid bilayer but sodium can't
   4. DBecause potassium has a negative equilibrium potential
6. 6What does the Goldman Hodgkin Katz equation consider than the Nernst equation does not?

   1. AConductance
   2. BRelative permeabilities of monovalent ions
   3. CRelative concentrations of ions
   4. DTemperature
7. 7This image shows the Hodgkin Goldman Katz equation. Fill in the blanks.

   

   1. Aout
   2. BNa+
   3. CNa+
   4. DIn
8. 8This diagram shows the voltage of a membrane during an action potential.
   At point A, the membrane is at [blank_start]rest[blank_end].
   At point B, the membrane is being [blank_start]depolarised[blank_end]. The membrane has increased permeability to [blank_start]sodium[blank_end] during this phase.
   At point C, the membrane is being [blank_start]repolarised[blank_end]. The membrane has increased permeability to [blank_start]potassium[blank_end] during this phase.
   At point D, the membrane is [blank_start]hyperpolarised[blank_end]. More [blank_start]potassium[blank_end] ions have moved out of the cell than are required for resting potential. During this period, another [blank_start]action potential[blank_end] cannot occur because a large amount of [blank_start]sodium[blank_end] will be required to overcome the [blank_start]threshold[blank_end].

   

   1. Arest
   2. Bdepolarised
   3. Csodium
   4. Drepolarised
   5. Epotassium
   6. Fhyperpolarised
   7. Gpotassium
   8. Haction potential
   9. Isodium
   10. Jthreshold
9. 9During propagation of an action potential, the amplitude of the action potential does not change.

   1. AVerdadero
   2. BFalso
10. 10Action potentials are triggered by exceeding a threshold of repolarisation.

    1. AVerdadero
    2. BFalso

11. 11What is conductance?

    1. AThe amount of current crossing a membrane
    2. BThe number of ions crossing a membrane
    3. CThe number of ions bound to a voltage-gated channel protein
    4. DThe charge on an ion
12. 12The unit of conductance is mho because conductance is the opposite of resistance and the unit of resistance is the ohm

    1. AVerdadero
    2. BFalso
13. 13What is the correct equation for charge?

    1. ACapacitance x voltage
    2. BCapacitance / voltage
    3. CCapacitance + voltage
    4. DVoltage / capacitance
14. 14If you inject charge into the centre of an axon, an action potential will be propagated in both directions.

    1. AVerdadero
    2. BFalso
15. 15There are two resistances found in axons.
    RL is longitudinal resistance along the [blank_start]axoplasm[blank_end].
    RM is membranal resistance across the [blank_start]membrane[blank_end].
    Membrane resistance is always [blank_start]greater[blank_end] than axoplasm resistance.

    1. Aaxoplasm
    2. Bmembrane
    3. Cgreater
16. 16This graph shows the differing conductances of sodium and potassium across a membrane. The [blank_start]slow[blank_end] efflux of potassium continues until the membrane is [blank_start]hyperpolarised[blank_end].

    

    1. Aslow
    2. Bhyperpolarised
17. 17What creates the 'foot' of the action potential?

    1. ALocalised circuits produced downstream of a previous action potential causing sodium channels to open
    2. BLocalised circuits produced downstream of a previous action potential causing potassium channels to open
    3. CLocalised circuits produced downstream of a previous action potential causing sodium channels to close
    4. DLocalised circuits produced downstream of a previous action potential causing potassium channels to close
18. 18Fill in the blanks in the text below to describe saltatory conduction.
    Schwann cells in [blank_start]peripheral[blank_end] nerves wrap around the axon. The myelin within them forms a high [blank_start]resistance[blank_end] 'seal' around the axonal membrane. In between each Schwann cell is a node of [blank_start]Ranvier[blank_end] which is [blank_start]unmyelinated[blank_end]. Current cannot cross the [blank_start]myelin[blank_end] so travels down through the [blank_start]axoplasm[blank_end] to a node of Ranvier where it flows out of the axon. This creates localised [blank_start]currents[blank_end].

    1. Aperipheral
    2. Bresistance
    3. CRanvier
    4. Dunmyelinated
    5. Emyelin
    6. Faxoplasm
    7. Gcurrents
19. 19Myelination [blank_start]increases[blank_end] conduction velocity. As axon diameter [blank_start]increases[blank_end], [blank_start]longitudinal[blank_end] resistance decreases. Membrane resistance [blank_start]increases[blank_end] in myelinated axons because current is forced through the [blank_start]axoplasm[blank_end] to the next node of [blank_start]Ranvier[blank_end]. Therefore, the conductance of the membrane [blank_start]decreases[blank_end] because charge is not stored at it.

    1. Aincreases
    2. Bincreases
    3. Clongitudinal
    4. Dincreases
    5. Eaxoplasm
    6. FRanvier
    7. Gdecreases
20. 20Unmyelinated axons have [blank_start]lower[blank_end] conduction velocity than myelinated axons. Axons with a smaller diameter have [blank_start]higher[blank_end] longitudinal resistance. However, their [blank_start]membrane[blank_end] resistance is lower because the current [blank_start]dissipates[blank_end] more quickly and voltage [blank_start]decreases[blank_end] more rapidly. This means that the [blank_start]conductance[blank_end] of the membrane is higher because voltage changes more slowly.

    1. Alower
    2. Bhigher
    3. Cmembrane
    4. Ddissipates
    5. Edecreases
    6. Fconductance
21. 21In this situation, is membrane conductance high or low?

    

    1. AHigh
    2. BLow
22. 22In this situation, is membrane conductance high or low?

    

    1. AHigh
    2. BLow
23. 23How much capacitance does 1cm^2 membrane have?

    1. A1 microfarrad
    2. B1 macrofarrad
    3. C10 coulombs
    4. D16 coulombs
24. 24How many coulombs of charge does one mole of a monovalent ion have?

    1. A96,500
    2. B55,000
    3. C6.02x10^23
    4. D10,000

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Principles of Physiology and Pharmacology Test sobre Action Potentials, creado por Charlotte Jakes el 04/12/2019.

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Charlotte Jakes

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