PHILS 15 - Measuring ion currents

during an action potential, the cell membrane

depolarizes and becomes positive

membrane depolarization produces an action potential because

it opens voltage-gated channels in the membrane

during an action potential, voltage-gated sodium channels open

before voltage-gated potassium channels

voltage-gated sodium channels close quickly after they open because

sodium channels inherently close soon after they open

voltage-gated potassium channels close because

the membrane depolarizes back to resting

the voltage clamp used in this experiment is used to measure

currents that flow across the membrane

The giant squid axon is used in this experiment because

all options are true

Before initiating the voltage clamp, the membrane potential of the giant squid axon was resting at a present value of

-60 mv

the voltage clamp will apply equally and opposite current to keep the membrane potential at

0mv

keeping the membrane potential at 0mV will

all options are true

the original line tracing (now gray) consists of

an initial inward current and then an outward current

which current was abolished when TEA is injected into the axon?

the (later) outward current

if TEA blocks voltage-gated potassium channels in the squid giant axon, which cations flow out of the cell and carry the (later) outward current?

potassium

the application of TTX to the solution bathing the axon changed the line tracing by abolishing

the initial inward current

If TTX blocks the voltage-gated sodium channels in the squid giant axon, which cation flows into the cell and carries the (early) inward current?

sodium