Chs 5 and 6 Practice

Which of the following distinguishes patch clamp recordings from traditional voltage clamp studies on the squid giant axon?

• In patch clamping, individual channels open and close rapidly, unlike the slower behavior in voltage clamp studies.

• The conductance of the channels is variable in patch clamping.

• The patterns of inward current in voltage clamping are more variable than in patch clamp recordings.

• Voltage clamping measures the summed current from all channels across the membrane, while patch clamping only measures current through one channel.

What effect does depolarization have on the activation gate of the Na+ channel?

• It increases the probability of the gate opening.

•  It does not affect the gate.

•  It increases the probability of the gate closing.

• It decreases the probability of the gate opening.

Why does a smaller axon result in slower conduction velocity?

• Smaller axons have more K+ channels, promoting ion leakage.

• Smaller axons have lower internal resistance, allowing current to spread farther.

• Smaller axons have higher internal resistance, making current spread slower.

• Smaller axons do not impact the speed of conduction

How does myelination increase conduction velocity?

• By increasing internal resistance

• By decreasing internal resistance

• By increasing membrane resistance and reducing ion leakage

• By decreasing the number of voltage-gated Na+ channels

Which of the following is true regarding the nodes of Ranvier?

• They contain a high concentration of voltage-gated channels to regenerate the action potential and allow conduction to the next myelinated segment.

• They are covered in myelin to speed up action potential conduction.

• They primarily function as synaptic sites for neurotransmitter release.

• They slow down action potential propagation to prevent overstimulation

These fibers are the smallest and have the slowest conduction velocity:

• A fibers

• B fibers

• C fibers

• D fibers