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21 terms

Chapter 11 part B

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…
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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