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WorksheetsQuiz on Membrane Potentials and Action Potentials
Total questions: 27
Worksheet time: 14mins
What is the primary reason for the electrical potentials across cell membranes?
Ion distribution
Cell size
Oxygen levels
Temperature variations
Which ion creates a diffusion potential of approximately -94 millivolts inside nerve fibers?
Sodium (Na+)
Calcium (Ca2+)
Potassium (K+)
Chloride (Cl-)
What does the Nernst equation calculate?
Ion concentration
Potential difference based on ion concentration ratios
Action potential duration
Membrane permeability
What is the resting membrane potential range for neurons?
-80 to -90 mV
-60 to -70 mV
-40 to -70 mV
-50 to -60 mV
How does the electrochemical driving force (Vdf) influence ion movement?
It only affects anions
It has no effect on ion movement
It predicts ion movement based on membrane potential and equilibrium potential
It predicts ion movement based on concentration only
What is the role of the Na+-K+ pump in maintaining resting membrane potential?
It passively allows ions to flow
It actively transports ions to create a net negative charge
It generates action potentials
It stabilizes the membrane
What is the combined effect of potassium and sodium diffusion on resting membrane potential?
-94 mV
+61 mV
-70 mV
-86 mV
What initiates the depolarization phase of an action potential?
Sodium channels opening
Calcium influx
Potassium channels opening
Chloride efflux
What is the significance of the all-or-nothing principle in action potentials?
Action potentials are always weak
Action potentials occur only if the threshold is reached
Action potentials are only generated in muscle cells
Action potentials can vary in strength
What is the primary function of voltage-gated sodium channels during an action potential?
To repolarize the membrane
To allow sodium ions to flow into the cell
To stabilize the resting potential
To prevent ion flow
How does myelination affect action potential transmission?
It prevents action potentials
It enhances speed and efficiency
It has no effect on transmission
It slows down the transmission
What is the role of calcium ions in action potentials?
They are not involved
They can initiate action potentials in some cells
They only affect muscle cells
They stabilize the membrane
What happens during the repolarization phase of an action potential?
Potassium ions exit the cell
Sodium ions exit the cell
Chloride ions exit the cell
Calcium ions enter the cell
What is the effect of local anesthetics on action potentials?
They increase sodium channel activation
They stabilize membranes and reduce excitability
They enhance excitability
They have no effect
What is the primary method used to measure membrane potential?
Using a spectrophotometer
Using a thermometer
Using a micropipette
Using a voltmeter
What is the significance of the absolute refractory period?
It allows for continuous action potentials
It prevents immediate re-excitation
It has no significance
It increases the frequency of action potentials
What is the primary contributor to the resting membrane potential?
Potassium diffusion
Sodium diffusion
Calcium influx
Chloride efflux
What is the primary function of the Goldman equation?
To calculate resting potential
To account for multiple ions in membrane potential
To measure ion flow
To determine action potential duration
What is the effect of high extracellular calcium on nerve excitability?
It decreases excitability
It has no effect
It increases excitability
It enhances action potentials
What is the role of impermeant anions in the axon?
They stabilize the membrane
They have no role
They contribute to the negative resting potential
They contribute to the positive potential
What is the primary characteristic of action potential plateaus in cardiac muscle?
Prolonged depolarization
Rapid depolarization
Rapid repolarization
No depolarization
What is the primary mechanism for the propagation of action potentials?
Chemical signaling
Passive diffusion
Electrical stimulation
Local circuits of current flow
What is the effect of sodium channel inactivation during an action potential?
It has no effect
It allows continuous depolarization
It prevents further depolarization until repolarization
It enhances sodium influx
What is the primary reason for the rapid rise in membrane potential during an action potential?
Potassium efflux
Sodium influx
Calcium influx
Chloride efflux
What is the primary role of the voltage clamp method?
To measure membrane potential
To study ion flow through specific channels
To stabilize membrane potential
To enhance action potentials
What is the primary factor that influences the speed of action potential transmission in myelinated fibers?
Temperature
Node of Ranvier
Cell size
Ion concentration
What is the primary effect of persistent sodium or calcium flow in cardiac pacemakers?
It has no effect
It leads to spontaneous rhythmic action potentials
It prevents action potentials
It stabilizes the membrane
