Exam 1 membrane Potential
True/False. A neuron at resting membrane potential mainly contains negative ions.
False
True/False. A neuron permeable to both K* and Na' will have a membrane potential of 0 mV.
False
True/False. Delayed rectifier channels are responsible for resting membrane potential.
False
True/False. Intracellular sodium is kept at low levels because of its role in signalling pathways.
False
True/False. Permeability for an ion is inversely related to conductance.
False
True/False. The ionic composition inside cells is similar to the composition of seawater.
False
True/False. The ionic gradients of a cell are disrupted in establishing resting membrane potential.
False
True/False. lonic concentration gradients are established by passive ionic flow through channels.
False
True/False. lonic gradients are established through the activity of ion channels.
False
True/False. The Goldman-Hodgkin-Katz equation predicts membrane potential more accurately than the Nernst equation because membranes are permeable to multiple ions.
True
True/False. The concentration of calcium is higher outside than inside a cell.
True
True/False. lon channels are selective for different types of ions.
True
True/False. lonic gradients are established by transporter proteins that consume ATP.
True
True/False. Neuronal membranes at rest are only permeable to potassium.
True
Match each biological feature with its electrical equivalent. Not all answers are used. Ionic gradients a) Battery b) Charge c) Conductance d) Current
A
Match each biological feature with its electrical equivalent. Not all answers are used. Membrane potential a) Battery b) Charge c) Conductance d) Current
A
Match the electrical concept with its biological equivalent. Not all answers are used. Voltage a) Electrochemical gradient b) Ion channels c) Ion transporters d) Ions e) Movement of ions
A
Match the neuronal electrical characteristic with its approximate value. Not all answers are used. Ek a) -80 mV b) -65 mV c) -40 mV d) Omv e) +55 mV
A
Resting membrane potential depends on all of the following ions, EXCEPT: a. Calcium b. Chloride c. Potassium d. Sodium e. Resting membrane potential depends on all of the above.
A
The resting membrane potential usually differs from the Nernst potential for potassium because a The membrane is permeable to multiple ions. b. The Nernst potential for sodium is more hyperpolarized than potassium. c. The neuronal membrane is semi-permeable to potassium. d. None of the above reasons explains the difference. e. None of the above. Resting potential usually equals Ex.
A
Two neurons have the same internal ionic concentrations and are bathed in the same external solution, yet differ in resting membrane potential. a The two differ in their permeability. bJ The Nernst potentials are different. C The sizes of the cells differ. d. The myelination of the cells differs. e. Any of the above could explain the different resting membrane potential of these two cells.
A
Two neurons have the same internal ionic concentrations and are bathed in the same external solution, yet differ in resting membrane potential. a The two differ in their permeability. bJ The Nernst potentials are different. e. The sizes of the cells differ. d. The myelination of the cells differs. e. Any of the above could explain the different resting membrane potential of these two cells.
A
What happens to a neuron if the external concentration of potassium increases? a The neuron depolarizes b. The neuron hyperpolarizes c. The membrane potential does not change d. The internal concentration adjusts to follow the membrane potential e. Not enough information to tell
A
If (K]out were to increase, the membrane potential of a typical neuron would: а. Нурегрolarize b. Depolarize c. Not change d. The effect depends on [K]. e. The effect depends on the permeability to other ions
B
In a series of experiments, Curtis and Cole increased the extracellular potassium concentration and observed that the membrane potential of the squid giant axon depolarized. This happened because: a. The intracellular concentration of potassium increased b. The Nemst potential for potassium depolarized c. The permeability of the membrane to potassium increased d. Other permeant ions changed concentration in response e. All of the above contributed to the depolarization.
B
Ionic concentration differ between the inside and outside of a cell because of: a. lon channels b.. lon transporters c. Chemical gradients d. Differences in ionic permeability e. Electrical activity, such as action potentials
B
Match each biological feature with its electrical equivalent. Not all answers are used. Ions a) Battery b) Charge c) Conductance d) Current
B
Match the electrical concept with its biological equivalent. Not all answers are used. Conductance a) Electrochemical gradient b) Ion channels c) Ion transporters d) Ions e) Movement of ions
B
Match the electrical concept with its biological equivalent. Not all answers are used. Resistance a) Electrochemical gradient b) Ion channels c) Ion transporters d) Ions e) Movement of ions
B
Match the neuronal electrical characteristic with its approximate value. Resting potential Not all answers are used. a) -80 mV b) -65 mV c) -40 mV d) Omv e) +55 mV
B
When ion channels in the membrane open, the membrane resistance: a. Increases b. Decreases C. Stays the same d. It depends on whether a current flows through the channel.
B
As the permeability of the membrane to an ion increases, which of the following occurs? a. The membrane potential depolarizes. b. The membrane potential hyperpolarizes. c. The membrane potential approaches the Nernst potential for the ion, d. The membrane potential goes away from the Nernst potential for the ion. e. None of the above. It depends on which ion.
C
Match each biological feature with its electrical equivalent. Not all answers are used. lon channels a) Battery b) Charge c) Conductance d) Current
C
Match the neuronal electrical characteristic with its approximate value. Not all answers are used. Action potential threshold a) -80 mV b) -65 mV c) -40 mV d) Omv e) +55 mV
C
When the extracellular potassium concentration increases, the resting membrane potential depolarizes because: a. Sodium channels open. B. Potassium channels open. C. The electrochemical gradient for potassium changes D. The concentration of potassium increases inside the cell. e. None of the above. Increased potassium causes hyperpolarization.
C
Match each biological feature with its electrical equivalent. Not all answers are used. Ionic flow a) Battery b) Charge c) Conductance d) Current
D
Match the electrical concept with its biological equivalent. Not all answers are used. Charge a) Electrochemical gradient b) Ion channels c) Ion transporters d) Ions e) Movement of ions
D
The Goldman-Hodgkin-Katz equation (GHK) differs from the Nernst equation in that: a. GHK is based on a simplified electric circuit model of the cell, but Nernst is not b. GHK is a weighted average of the Nernst potentials of different ions c. GHK does not take into account the valence of ions, but Nernst does d. GHK incorporates the effects of multiple ions, but Nernst does not e. GHK and Nernst differ in all of the above ways.
D
The resting membrane potential differs from Ek because of all of the following EXCEPT: a. The membrane is permeable to sodium b. The membrane is permeable to chloride c. The membrane potential follows the GHK equation d The membrane is not significantly permeable to potassium e. Resting potential differs from Ek for all of the above reasons.
D
According to the Goldman-Hodgkin-Katz equation, when the permeability to an ion is high, the membrane potential is close to: a. -61 mV b. 0mV c. Ek d. ENa e. The Nemst potential of that ion
E
In the Goldman-Hodgkin-Katz equation, the contribution of ion to resting membrane potential depends on all of the following., EXCEPT a. The ion's valence b. Its internal concentration c. Its external concentration d Its permeability through the membrane e.The ion's contribution depends on all of the above.
E
In the experiment discussed in class (see figure at right), when the extracellular potassium concentration was changed, the membrane potential diverged from the straight line predicted, because: a The value of [K]out Was measured incorrectly b. The membrane potential does not depend on potassium c. Potassium interferes with the permeability of other ions d. The Nernst equation does not apply at low ion concentrations e. The membrane potential depends on additional ions besides potassium
E
Match the electrical concept with its biological equivalent. Not all answers are used. Current a) Electrochemical gradient b) Ion channels c) Ion transporters d) Ions e) Movement of ions
E
The Goldman-Hodgkin-Katz equation differs from the Nernst equation in that GHK: a predicts the potential across a membrane. B. depends on temperature. c. depends on ionic concentration inside the cell. d. is a logarithmic relationship. e. The two equations differ in none of the above respects.
E
The Goldman-Hodgkin-Katz equation differs from the electrical equivalence approach to estimating the membrane potential in that: a. Only GHK has temperature dependence. b. Only GHK takes ion concentrations into account. c. Only electrical equivalence is based on well-described physical laws. d. Only electrical equivalence takes membrane permeability into account. e None of the above.
E
True/False. In a normal neuron at resting membrane potential, there is a flux of chloride ions.
True
True/False. In a normal neuron at resting membrane potential, there is a flux of potassium ions.
True
True/False. In a normal neuron at resting membrane potential, there is a flux of sodium ions.
True
True/False. At resting membrane potential, the net ionic current is 0.
True
True/False. At resting membrane potential, there is no flow of ions.
True
