TEST BANK For Principles of Human Physiology, 6th Edition by
Stanfield
On what portion of the neuron do action potentials propagate? - ANSWER:axon
An action potential originates at the _______ and travels along the axon until it
reaches the __________. - ANSWER:axon hillock : axon terminal
What type of ion channels in the membrane of neurons allows ions to move across
the membrane at rest and thereby contribute to resting membrane potential? -
ANSWER:leak channels
What type of ion channels in the membrane of neurons open or close in response to
a neurotransmitter binding to its receptor? - ANSWER:ligand-gated channel
In a neuron, where is the greatest concentration of voltage-gated sodium and
voltage-gated potassium channels? - ANSWER:axon hillock
In a neuron, where are voltage-gated calcium channels located? - ANSWER:axon
terminal
Which of the following best describes the function of the myelin sheath? -
ANSWER:reduce a membrane's ion permeability (reduces leakage of ions across the
cell membrane).
At rest, the plasma membrane is more permeable to which of the following ions? -
ANSWER:potassium (k+)
Where in the neuron are the nucleus and most of the organelles contained? -
ANSWER:cell body (soma)
Ions are unequally distributed across the plasma membrane of all cells. This ion
distribution creates an electrical potential difference across the membrane. What is
the name given to this potential difference? - ANSWER:Resting membrane potential
(RMP)
Sodium and potassium ions can diffuse across the plasma membranes of all cell
because of the presence of what type of channel? - ANSWER:leak channels
On average, the resting membrane potential is -70 mV. What does the sign and
magnitude of this value tell you? - ANSWER:the inside surface of the plasma
membrane is much more negatively charged that the outside surface.
, The plasma membrane is much more permeable to K+ than to Na+. Why? -
ANSWER:There are many more K+ leak channels than Na+ leak channels in the
plasma membrane.
the resting membrane potential depends on two factors that influence the
magnitude and direction of Na+ and K+ diffusion across the plasma membrane.
Identify these two factors. - ANSWER:the presence of concentration gradients and
leak channels
What prevents the Na+ and K+ gradients from dissipating? - ANSWER:Na+/K+ ATPase
At resting membrane potential , the membrane is most permeable to __________,
which moves _________ the cell due to its electrochemical gradient. -
ANSWER:potassium : out of
The _______ maintains the resting membrane potential. - ANSWER:Na+/K+ pump
Which of the following ion channels located in the plasma membrane of the neuron
are always open and are largely responsible for the resting membrane potential? -
ANSWER:leak channels
What is the approximate resting membrane potential of neurons? - ANSWER:-70 mV
The membrane of neurons at rest are very permeable to _____ but only slightly
permeable to _______. - ANSWER:K+ ; Na+
During depolarization, which gradient(s) move(s) Na+ into the cell? - ANSWER:both
the electrical and chemical gradients
What is the resting membrane potential for most neurons? - ANSWER:-70 mV
The Na+/K+ pump actively transports both sodium and potassium ion across the
membrane to compensate for their constant leakage. In which direction is each ion
pumped? - ANSWER:Na+ is pumped out of the cell and K+ is pumped into the cell
The concentrations of which two ions are highest outside the cell? - ANSWER:Na+
and Cl-
What type of conduction takes place in unmyelinated axons? - ANSWER:Continuous
conduction
An action potential is self-generating because _________. - ANSWER:depolarizing
currents established by the infux of Na+ flow down the axon and trigger an action
potential at the next segment
Stanfield
On what portion of the neuron do action potentials propagate? - ANSWER:axon
An action potential originates at the _______ and travels along the axon until it
reaches the __________. - ANSWER:axon hillock : axon terminal
What type of ion channels in the membrane of neurons allows ions to move across
the membrane at rest and thereby contribute to resting membrane potential? -
ANSWER:leak channels
What type of ion channels in the membrane of neurons open or close in response to
a neurotransmitter binding to its receptor? - ANSWER:ligand-gated channel
In a neuron, where is the greatest concentration of voltage-gated sodium and
voltage-gated potassium channels? - ANSWER:axon hillock
In a neuron, where are voltage-gated calcium channels located? - ANSWER:axon
terminal
Which of the following best describes the function of the myelin sheath? -
ANSWER:reduce a membrane's ion permeability (reduces leakage of ions across the
cell membrane).
At rest, the plasma membrane is more permeable to which of the following ions? -
ANSWER:potassium (k+)
Where in the neuron are the nucleus and most of the organelles contained? -
ANSWER:cell body (soma)
Ions are unequally distributed across the plasma membrane of all cells. This ion
distribution creates an electrical potential difference across the membrane. What is
the name given to this potential difference? - ANSWER:Resting membrane potential
(RMP)
Sodium and potassium ions can diffuse across the plasma membranes of all cell
because of the presence of what type of channel? - ANSWER:leak channels
On average, the resting membrane potential is -70 mV. What does the sign and
magnitude of this value tell you? - ANSWER:the inside surface of the plasma
membrane is much more negatively charged that the outside surface.
, The plasma membrane is much more permeable to K+ than to Na+. Why? -
ANSWER:There are many more K+ leak channels than Na+ leak channels in the
plasma membrane.
the resting membrane potential depends on two factors that influence the
magnitude and direction of Na+ and K+ diffusion across the plasma membrane.
Identify these two factors. - ANSWER:the presence of concentration gradients and
leak channels
What prevents the Na+ and K+ gradients from dissipating? - ANSWER:Na+/K+ ATPase
At resting membrane potential , the membrane is most permeable to __________,
which moves _________ the cell due to its electrochemical gradient. -
ANSWER:potassium : out of
The _______ maintains the resting membrane potential. - ANSWER:Na+/K+ pump
Which of the following ion channels located in the plasma membrane of the neuron
are always open and are largely responsible for the resting membrane potential? -
ANSWER:leak channels
What is the approximate resting membrane potential of neurons? - ANSWER:-70 mV
The membrane of neurons at rest are very permeable to _____ but only slightly
permeable to _______. - ANSWER:K+ ; Na+
During depolarization, which gradient(s) move(s) Na+ into the cell? - ANSWER:both
the electrical and chemical gradients
What is the resting membrane potential for most neurons? - ANSWER:-70 mV
The Na+/K+ pump actively transports both sodium and potassium ion across the
membrane to compensate for their constant leakage. In which direction is each ion
pumped? - ANSWER:Na+ is pumped out of the cell and K+ is pumped into the cell
The concentrations of which two ions are highest outside the cell? - ANSWER:Na+
and Cl-
What type of conduction takes place in unmyelinated axons? - ANSWER:Continuous
conduction
An action potential is self-generating because _________. - ANSWER:depolarizing
currents established by the infux of Na+ flow down the axon and trigger an action
potential at the next segment
