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Depolarization of the plasma membrane occurs if there is an increase in the extracellular K+ ion concentration. Hyperpolarization would occur if the extracellular K+ ion concentration decreased, not increased. If the permeability of the plasma membrane to K+ ions increases, hyperpolarization of the membrane would occur as the inside of the cell becomes more negative as the K+ ions make their way out of the cell. Even with an increase in the extracellular Na+ ion concentration, there would be li…

If there is an increase in extracellular K+ ion concentration, the result is

depolarization of the plasma membrane

If the permeability of the plasma membrane to K+ ions increases, the result is

hyperpolarization of the plasma membrane

If there is an increase in the extracellular Na+ ion concentration, the result is

little, if any, change in the resting membrane potential of the plasma membrane

Voltage-gated Na+ ion channels are sensitive to changes in the extracellular concentration of

Ca2+ ions

Small depolarizations of the plasma membrane, regardless of the cause of the depolarization, cause

voltage-gated Na+ ion channels to open

Action potentials occur when the local potential

reaches the threshold

When the plasma membrane is at rest, activation gates of the voltage-gated Na+ ion channels are __________ and inactivation gates are __________ .

closed, open

The depolarization phase of the action potential begins when

Na+ ions move into the cell

Which of the following is found in the central nervous system?

tract

Which of the following is found in the central nervous system?

tract

When a nerve cell membrane changes from positive inside to negative inside, the cell membrane is undergoing

repolarization

Which type of propagation occurs along a myelinated axon?

saltatory

Saltatory propagation

type of fast conduction between nodes of Ranvier along myelinated axons

Which of the following statements is NOT true concerning the resting membrane potential?

Sodium ions are in relatively higher concentration inside the cell than outside.

During the repolarization phase of an action potential, which of the following is the primary activity?

Potassium ions are flowing out of the cell

The threshold of a neuron is the

voltage that triggers activation of voltage-gated channels

During the depolarization phase of an action potential, which of the following situations exists?

The inside of the membrane is becoming more positive with respect to the outside.

local potentials

are non-propagating

The one-way nature of action potential propagation down an axon is primarily due to

the refractory period

The absolute refractory prevents the recently-depolarized portion of the membrane from depolarizing again

an action potential can only travel in one direction

In the resting state of the membrane, which of the following situations exists for voltage-gated sodium ion channels?

The inactivation gate is open and the activation gate is closed

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