Quiz on Membrane Potentials and Action Potentials

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