Membrane Potentials

1. 1When we record the intracellular membrane potential, we place an electrode [blank_start]across[blank_end] the cell membrane to measure from outside to inside. The external potential is taken as [blank_start]0[blank_end]mV. We then measure the [blank_start]difference[blank_end] between this value and the potential of the [blank_start]inner[blank_end] membrane.

   1. Aacross
   2. B0
   3. Cdifference
   4. Dinner
2. 2When we record the extracellular membrane potential, we bring an electrode [blank_start]close to[blank_end] the cell membrane. We also measure from a distant point. The potential at this distant point is taken as [blank_start]0[blank_end]mV.

   1. Aclose to
   2. B0
3. 3Which method of measuring membrane potential will record a smaller action potential waveform?

   1. AIntracellular
   2. BExtracellular
4. 4If we record membrane potential intracellularly or extracellular the waveform of voltage over time will be the same for both measurements.

   1. ATrue
   2. BFalse
5. 5Fill in the blanks below to describe the technique of patch clamping when measuring membrane potentials.
   1. The electrode tip is broken off and [blank_start]smoothed[blank_end] in a Bunsen flame.
   2. The tip is brought down onto the [blank_start]membrane[blank_end].
   3. A small amount of [blank_start]suction[blank_end] is applied via the pipette.
   4. This creates a [blank_start]high resistance[blank_end] seal so that all ions flowing when a single ion channel opens must flow into the [blank_start]pipette[blank_end]. This allows measurement of [blank_start]single-channel[blank_end] currents.

   1. Asmoothed
   2. Bmembrane
   3. Csuction
   4. Dhigh resistance
   5. Epipette
   6. Fsingle-channel
6. 6This image shows the recorded membrane potential over a single ion channel. The decrease in potential shows the channel is open.

   

   1. ATrue
   2. BFalse
7. 7Why is the plasma membrane described as being a capacitor?

   1. AIt stores ionic charges on its inner and outer surfaces
   2. BIt stores ionic charges on its outer surface only
   3. CIt contains ion channels
   4. DIt prevents the movement of ions from diffusing freely across, allowing the intra and extracellular fluids to have differing potentials
8. 8Fill in the blanks to describe the action of the ATPase sodium-potassium pump.
   1. [blank_start]3[blank_end] Na+ and [blank_start]1[blank_end] ATP molecule bind at the [blank_start]cytosolic[blank_end] binding site
   2. [blank_start]ADP[blank_end] is released causing a conformational shape change
   3. [blank_start]3[blank_end] Na+ are released into the extracellular space and [blank_start]2[blank_end] K+ bind on the same side
   4. [blank_start]Inorganic phosphate[blank_end] is released causing another conformational shape change
   5. [blank_start]2[blank_end] K+ are released into the cytosol

   1. A3
   2. B1
   3. Ccytosolic
   4. DADP
   5. E3
   6. F2
   7. GInorganic phosphate
   8. H2
9. 9What is the typical intracellular concentration of potassium?

   1. A140mM
   2. B10mM
   3. C2mM
   4. D4mM
10. 10What is the typical intracellular concentration of sodium?

    1. A140mM
    2. B10mM
    3. C4mM
    4. D40mM

11. 11What is the extracellular concentration of potassium?

    1. A4mM
    2. B140mM
    3. C10mM
    4. D110mM
12. 12What is the typical extracellular concentration of sodium?

    1. A140mM
    2. B10mM
    3. C4mM
    4. D15mM
13. 13An electrochemical gradient is a store of potential energy that can do what?

    1. ABe used to do work in the form of ions moving across the membrane
    2. BKill a cell
    3. COpen a ligand-gated ion channel
    4. DStimulate mitosis
14. 14Why is the membrane potential at 0 here?

    

    1. AThere are no open ion channels so charge cannot transfer across the membrane
    2. BEach size has equal amounts of positive and negative charge
    3. CBecause the inside is more positive than the outside
    4. DBecause there is no action potential
15. 15The open ion channel here must be selective for [blank_start]potassium[blank_end]. Therefore, this ion crosses the membrane from the [blank_start]inside[blank_end] of the cell to the region of lower concentration [blank_start]outside[blank_end] the cell. This ion 'sits' on the external membrane layer due to its property of [blank_start]capacitance[blank_end]. The cytosol is now [blank_start]more[blank_end] negative than the extracellular fluid, so the membrane potential is [blank_start]negative[blank_end].

    

    1. Apotassium
    2. Binside
    3. Coutside
    4. Dcapacitance
    5. Emore
    6. Fnegative
16. 16In this image, another ion pair has come to sit across the membrane. The membrane potential becomes even more [blank_start]negative[blank_end] because there are even more [blank_start]negative[blank_end] charges aligned on the [blank_start]inner[blank_end] membrane. The green region represents a 'shell' of [blank_start]charge[blank_end] developing across the membrane.

    

    1. Anegative
    2. Bnegative
    3. Cinner
    4. Dcharge
17. 17Why do we need to do work in order to rearrange ions across the membrane?

    1. AOppositely charged ions are attracted to one another but we need to overcome this attraction to separate them across the membrane
    2. BWe need energy to open the ion-specific channels
    3. CWe need energy to move the ions against their concentration gradients
18. 18How do we determine the gradient of a positive ion across a membrane?

    1. A[external] / [internal]
    2. B[internal] / [external]
    3. C[internal] x [external]
    4. DR x T / z x F
19. 19Fill in the blanks to explain this diagram.
    The Na+/K+ pump drives ions in one direction to create a [blank_start]concentration gradient[blank_end]. However, this creates electrical drag-back in the [blank_start]opposite[blank_end] direction. Oppositely charged ions [blank_start]attract[blank_end] one another, so will prevent each other from leaving the cell. At the point where the force of the [blank_start]concentration gradient[blank_end] pushing an ion out of its cell matches the electrical force pulling it back in there will be no net [blank_start]movement[blank_end].

    

    1. Aconcentration gradient
    2. Bopposite
    3. Cattract
    4. Dconcentration gradient
    5. Emovement
20. 20What is the equilibrium potential?

    1. AThe electrical force in voltage required to balance the osmotic force of an ion
    2. BThe difference in voltage in a cell's cytosol compared to the extracellular fluid
    3. CThe minimum potential required to stimulate an action potential
    4. DThe lowest voltage a cell reaches during an action potential firing
21. 21How do we calculate electrical work across a cell?

    1. AEquilibrium potential x valence of ion x conversion factor
    2. BEquilibrium potential x valence of ion / conversion factor
    3. CEquilibrium potential / conversion factor x valence of ion
    4. DEquilbirium potential x valence of ion
22. 22How do we calculate osmotic work across a cell?

    1. AGas constant x temperature x ln[gradient]
    2. BGas constant / temperature x ln[gradient]
    3. CGas constant x temperature x log[gradient]
    4. DGas constant x temperature / ln[gradient]
23. 23At the equilibrium potential of an ion, the electrical work done is equal to osmotic work done.

    1. ATrue
    2. BFalse
24. 24How do we calculate equilibrium potential?

    1. ART/zF x ln[gradient]
    2. BRz/TF x ln[gradient]
    3. CRT/zF x log[gradient]
    4. DE x z x F
25. 25How do we simplify the Nernst equation to calculate the equilibrium potential of a single charged ion?

    1. AE = 61.5 x log([external]/[internal])
    2. BE = 30.75 x log([external]/[internal])
    3. CE = 61.5 x ln([external]/[internal])
    4. DE = 30.75 x ln([external]/[internal])

Description

Principles of Physiology and Pharmacology Quiz on Membrane Potentials, created by Charlotte Jakes on 27/11/2019.

Author

Charlotte Jakes

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English

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History

Created on 27 Nov 2019 · updated on 27 Nov 2019

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pppprinciples of physiology and pharmacology

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