Voltage-Dependent Membrane Permeability

What best describes use of the voltage clamp method in neuroscience?

• measuring ionic movement in a living organism

• measuring the resting membrane potential of a cell

• manipulation of the resting membrane potential in a cell

• changing the voltage of a cell

• controlling the membrane potential of a cell while measuring the resulting ionic currents

Which statement about Na⁺ permeability during an action potential is most accurate?

• It is long lasting.

• It is responsible for the rising phase of the action potential.

• It is responsible for the falling phase of the action potential.

• It restores the membrane potential to its usual level following the action potential.

• All of the above

The voltage clamp method controls the _______ at any desired level.

• amplitude of an action potential

• frequency of an action potential

• membrane potential

• K⁺ current

• Na⁺ current

Tags

NGSS.HS-PS3-5

The classic voltage clamp technique would be suitable for which application?

• Indirect measurement of unidirectional current flowing through cell membrane.

• Direct measurement of current flowing through the cell membrane.

• Measurement of current flowing through a single ion channel.

• Study of the ionic composition of the intracellular environment.

• Evaluation of effects of large intracellular molecules on the function of ion channels.

Which current corresponds to a flow of Na⁺ in response to a depolarizing stimulus in a giant axon of a squid?

• Outward capacitive current.

• Transient inward current.

• Delayed outward current.

• Prolonged outward current.

Which is the key event at a membrane potential of 0 mV?

• The late outward current increases in magnitude.

• The late outward current decreases in magnitude.

• The early current reverses its polarity.

• The early and late currents flow inward.

• The early current is at its maximum.

In the experiments conducted by Hodgkin and Huxley, the early current disappeared if the membrane was clamped at _______ mV.

• 0
• -26

• +26

• +52

• +65

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

Practically speaking, how would you determine that Na⁺ influx into a cell underlies the early current?

• Replace intracellular Na⁺ with its radioactive form and trace its movement across the membrane.

• Remove Na⁺ from the extracellular compartment and assess the early current under new conditions.

• Use the voltage clamp method to measure the current.

• Remove K⁺ from the intracellular compartment and assess the early current under the new conditions.

• Treat the cell with tetraethylammonium.

Membrane potential depolarizes, Na⁺ channels open, Na⁺ current increases, _______, _______, and _______. (Select all that apply)

• K⁺ channels open

• Na⁺ channels close

• Na⁺ current decrease

• Na⁺ current increase

• membrane potential hyperpolarizes

Which statement correctly differentiates between the passive and active current in a myelinated axon?

• The passive current flows only in the nodes of Ranvier, unlike the active current.

• The active current flows only in the nodes of Ranvier, unlike the passive current.

• The passive current flows in one direction along the axon, unlike the active current.

• The action potential propagation depends on the passive current only.

• The action potential propagation depends on the active current only.