Action Potentials and Neuronal Conduction

Fill-in-the-blank practice flashcards for review of action potentials, ion channels, voltage clamp experiments, and axonal propagation.

Hodgkin and Huxley investigated membrane permeability using a squid axon and the __________ technique.

voltage clamp

In 1963, Hodgkin and Huxley won the Nobel Prize for their work on membrane permeability along with __________.

Eccles

In a resting neuron, the concentration of $K^+$ is higher inside the cell, while the concentration of __________ is higher outside the cell.

$$Na^+$$

During membrane depolarization, two ionic currents occur: a transient inward current and a delayed __________ current.

outward

By removing external $Na^+$ from outside the cell, researchers showed that the transient inward current is caused by ___________.

$$Na^+$$

By using radioactive $K^+$, researchers determined that the delayed outward current is caused by __________.

$$K^+$$

The neurotoxin tetrodotoxin blocks __________ channels.

$$Na^+$$

The compound tetraethylammonium blocks __________ channels.

$$K^+$$

In humans, a typical action potential threshold occurs when the membrane potential moves from rest (~$-70\,mV$) to __________.

$$-55\,mV$$

The __________ principle states that an action potential is either created completely or not created at all.

all-or-none

In neuronal communication, signal intensity is coded through firing __________.

rates

The __________ gate of a voltage-gated $Na^+$ channel opens only when depolarization occurs.

activation

The __________ gate of a voltage-gated $Na^+$ channel is open at rest and closes a short time after depolarization.

inactivation

The opening of voltage-gated $K^+$ channels causes repolarization, forming a __________ feedback loop.

negative

The $Na^+/K^+$ pump actively transports $Na^+$ out of the cell and $K^+$ into the cell using ___________.

ATP

The $Na^+/K^+$ pump accounts for __________ of brain energy consumption.

$$20 - 40\%$$

The conduction velocity of an unmyelinated axon ranges from __________.

$$0.7 - 2.3\,m/s$$

The conduction velocity of a myelinated axon ranges from __________.

$$70 - 120\,m/s$$

In myelinated axons, action potentials are generated at specific gaps called the __________.

nodes of Ranvier

Backward propagation of an action potential along the axon is prevented by the __________ period.

refractory