Question 1

Which of the following are phagocytic glial cells that fight infection and remove debris?
A)microglia
B)oligodendrocytes
C)Schwann cells
D)myelin sheath cells
E)astrocytes

Accepted Answer

Microglia are the primary immune defense in the central nervous system and act as phagocytes, removing pathogens and debris.

Question 2

A drug that specifically inhibits voltage-gated calcium channels would most directly inhibit
A)depolarization of nerve cell membranes.
B)repolarization after depolarization of nerve cell membranes.
C)hyperpolarization of nerve cell membranes.
D)presynaptic neurotransmitter release.
E)postsynaptic receptor signal response.

Accepted Answer

Voltage-gated calcium channels are crucial for the release of neurotransmitters from presynaptic terminals. When an action potential reaches the terminal, these channels open, allowing calcium to enter the cell. This influx of calcium triggers the fusion of neurotransmitter-containing vesicles with the presynaptic membrane, leading to neurotransmitter release into the synaptic cleft. Inhibiting these channels would directly impair this process, reducing or preventing neurotransmitter release.

Question 3

Although they are smaller than K⁺,Na⁺ ions fail to pass through K⁺channels because Na⁺ A)is repulsed by positively charged amino acids at the mouth of the channel. B)is too small to interact with oxygen atoms in amino acids on all sides of the channel and therefore does not completely lose its waters of hydration. C)is always transported complexes to Cl⁻. D)is always transported in a complex with two other Na⁺ ions. E)is attracted by other Na⁺ ions,which are at higher concentration outside than inside the cell.

Accepted Answer

Na+ ions fail to pass through K+ channels because they are too small to interact effectively with the oxygen atoms lining the channel, preventing them from shedding their hydration shell, which is necessary for passage through the channel.

Question 4

You are examining an organism recently found on Mars and are currently trying to identify one of its neurotransmitters.Biochemical characterization indicates that it is a derivative of the amino acid tyrosine,so you classify the novel neurotransmitter as a(n)
A)acetylcholine analogue.
B)catecholamine.
C)neuropeptide.
D)serotonin analogue.
E)GABA analogue.

Accepted Answer

Catecholamines are neurotransmitters in the brain that are derived from the amino acid tyrosine. Examples include dopamine, norepinephrine, and epinephrine. Since the novel neurotransmitter is a derivative of tyrosine, it fits the classification of a catecholamine.

Question 5

You have added a specific amount of excitatory neurotransmitter mixed with a 6× higher concentration of an inhibitory neurotransmitter to a synaptic cleft.You expect that the postsynaptic neuron will
A)produce 6× its normal number of action potentials.
B)produce 6× its normal number of negative action potentials.
C)show a net hyperpolarization as a result of neuronal integration.
D)show a net depolarization as a result of neuronal integration.
E)not respond to either signal.

Accepted Answer

The presence of a higher concentration of inhibitory neurotransmitter compared to the excitatory neurotransmitter in the synaptic cleft would lead to a net hyperpolarization of the postsynaptic neuron. This is because the inhibitory signals would outweigh the excitatory ones, making the neuron less likely to fire an action potential.

Question 6

Each of the following statements is true about the nicotinic acetylcholine receptor except
A)the actions of acetylcholine can be mimicked by nicotine.
B)it binds one molecule of acetylcholine for activity.
C)the open channel allows an influx of sodium ions.
D)biochemical purification was aided by the use of cobratoxin.
E)it is made up of five large subunits.

Accepted Answer

The nicotinic acetylcholine receptor requires the binding of two molecules of acetylcholine for activation, not just one, making statement B incorrect.

Question 7

Each of the following is a correct relationship between action potential phase and channel status except A)depolarization; Na⁺channels open. B)repolarizing phase; Na⁺channels closed. C)repolarizing phase; K⁺channels open. D)hyperpolarizing phase; Na⁺channels open. E)hyperpolarizing phase; K⁺ channels open.

Accepted Answer

During the hyperpolarizing phase of an action potential, sodium channels (Na+) are not open; they are in fact closed or inactivated, which helps to restore the resting membrane potential. Potassium channels (K+), on the other hand, may still be open, contributing to the hyperpolarization.

Question 8

Catecholamines are synthesized by the
A)adrenal gland.
B)anterior pituitary gland.
C)skeletal muscle.
D)Schwann cells.
E)hypothalamus.

Accepted Answer

Catecholamines, which include hormones such as adrenaline (epinephrine), noradrenaline (norepinephrine), and dopamine, are primarily synthesized by the adrenal glands, specifically in the medulla part of the adrenal glands.

Question 9

Multiple sclerosis is a result of
A)demyelination of nerve cells.
B)excess myelin on nerve cells.
C)a decrease in postsynaptic receptors.
D)blocking the nodes of Ranvier.
E)proteolytic cleavage of presynaptic SNARE proteins.

Accepted Answer

Multiple sclerosis is characterized by the demyelination of nerve cells, which disrupts the normal function of the nervous system.

Question 10

The intracellular stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in
A)potassium ion levels.
B)chloride ion levels.
C)sodium ion levels.
D)calcium ion levels.
E)acetylcholine levels.

Accepted Answer

The intracellular stimulus for the secretion of neurotransmitters into the synaptic cleft is an increase in calcium ion levels. When an action potential reaches the axon terminal, it triggers the opening of voltage-gated calcium channels, allowing calcium ions to enter the neuron. This influx of calcium ions initiates the fusion of synaptic vesicles with the plasma membrane, leading to the release of neurotransmitters into the synaptic cleft.

Question 11

The maximum membrane potential that an ion gradient can produce is the
A)action potential.
B)membrane potential.
C)equilibrium potential.
D)threshold potential.
E)resting potential.

Accepted Answer

The equilibrium potential is the maximum membrane potential that an ion gradient can produce. It is defined by the Nernst equation and represents the electrical potential difference that exactly balances an ionic concentration gradient, preventing net ion movement across the membrane.

Question 12

Sarin nerve gas paralyzes muscle by interfering with neuronal transmission by which of the following?
A)serotonin
B)GABA
C)acetylcholine
D)encephalin
E)glutamate

Accepted Answer

Sarin nerve gas inhibits acetylcholinesterase, an enzyme responsible for breaking down acetylcholine in the synaptic cleft. This leads to an accumulation of acetylcholine, resulting in continuous stimulation of muscles, which can cause paralysis.

Question 13

Hyperpolarization of the postsynaptic nerve terminal
A)decreases the chance that an action potential will be initiated.
B)increases the chance that an action potential will be initiated.
C)has no effect on the initiation of an action potential.
D)is stimulated by an influx of calcium ions.
E)sensitizes receptors to activation by lower levels of neurotransmitter.

Accepted Answer

Hyperpolarization of the postsynaptic nerve terminal makes the inside of the cell more negative compared to the outside, moving the membrane potential further away from the threshold needed to initiate an action potential, thus decreasing the chance that an action potential will be initiated.

Question 14

Each of the following is a voltage-gated Na⁺ channel property except A)opens rapidly when stimulated. B)closes rapidly in absence of stimulus. C)opens to a variable extent depending on how much the stimulus voltage exceeds the threshold voltage. D)has a voltage sensor helix that controls channel gating. E)can be inactivated by the inactivating particle part of the channel protein.

Accepted Answer

Voltage-gated Na+ channels do not open to a variable extent depending on how much the stimulus voltage exceeds the threshold voltage; they either open or remain closed, following the all-or-none principle.

Question 15

Sodium channels are concentrated in the
A)axon hillock and nodes of Ranvier.
B)dendrites and synaptic boutons.
C)dendrites and nodes of Ranvier.
D)dendrites and axon hillock.
E)synaptic boutons and axon hillock.

Accepted Answer

Sodium channels are concentrated in the axon hillock and nodes of Ranvier, which are key areas for the initiation and propagation of action potentials in neurons.

Question 16

Leak channels make a neuronal membrane at steady state approximately ________ permeable to K⁺ than to Na⁺. A)half as B)equally C)twice as D)10 times more E)100 times more

Accepted Answer

At steady state, the neuronal membrane is approximately 100 times more permeable to K+ than to Na+ due to the presence of more K+ leak channels compared to Na+ leak channels.

Question 17

Which equation best describes the relationship between an ion gradient and the equilibrium potential that will form when the membrane is permeable to only that ion?
A)Huxley equation
B)Goldman equation
C)Nernst equation
D)Hodgkin equation
E)Katz equation

Accepted Answer

The Nernst equation describes the relationship between the ion gradient across a membrane and the equilibrium potential for that specific ion when the membrane is permeable only to that ion. It calculates the voltage necessary to balance the concentration gradient of the ion, preventing net movement across the membrane.

Question 18

The phase at the end of an action potential when the membrane potential becomes more negative than it is at rest is the ________ phase.
A)threshold
B)depolarizing
C)repolarizing
D)hyperpolarizing
E)refractory

Accepted Answer

The hyperpolarizing phase occurs when the membrane potential becomes more negative than the resting potential, often due to potassium channels remaining open longer than the duration of the action potential, allowing excess potassium to leave the cell.

Question 19

________ is a technique used to measure ion currents passing through individual channels along a nerve cell.

Accepted Answer

The answer of ________ is a technique used to measure...

Question 20

The technique that can be used to record ion currents passing through individual channels is known as
A)voltage-gating.
B)ligand-gating.
C)patch-clamping.
D)ion sensors.
E)optogenetics.

Accepted Answer

Patch-clamping is a widely used electrophysiological technique for recording ion currents through individual ion channels in cells. This method allows for the measurement of the electrical currents that pass through the ion channels when they open or close, providing detailed information about the channel's properties and function.

Quiz 22: Signal Transduction Mechanisms: Ielectrical and Synaptic Signaling in Neurons

Which of the following are phagocytic glial cells that fight infection and remove debris?

A drug that specifically inhibits voltage-gated calcium channels would most directly inhibit

Although they are smaller than K+,Na+ ions fail to pass through K+ channels because Na+

You are examining an organism recently found on Mars and are currently trying to identify one of its neurotransmitters.Biochemical characterization indicates that it is a derivative of the amino acid tyrosine,so you classify the novel neurotransmitter as a(n)

You have added a specific amount of excitatory neurotransmitter mixed with a 6× higher concentration of an inhibitory neurotransmitter to a synaptic cleft.You expect that the postsynaptic neuron will

Each of the following statements is true about the nicotinic acetylcholine receptor except

Each of the following is a correct relationship between action potential phase and channel status except

Catecholamines are synthesized by the

Multiple sclerosis is a result of

The intracellular stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in

The maximum membrane potential that an ion gradient can produce is the

Sarin nerve gas paralyzes muscle by interfering with neuronal transmission by which of the following?

Hyperpolarization of the postsynaptic nerve terminal

Each of the following is a voltage-gated Na+ channel property except

Sodium channels are concentrated in the

Leak channels make a neuronal membrane at steady state approximately ________ permeable to K+ than to Na+.

Which equation best describes the relationship between an ion gradient and the equilibrium potential that will form when the membrane is permeable to only that ion?

The phase at the end of an action potential when the membrane potential becomes more negative than it is at rest is the ________ phase.

________ is a technique used to measure ion currents passing through individual channels along a nerve cell.

The technique that can be used to record ion currents passing through individual channels is known as

Although they are smaller than K⁺,Na⁺ ions fail to pass through K⁺channels because Na⁺

Each of the following is a voltage-gated Na⁺ channel property except

Leak channels make a neuronal membrane at steady state approximately ________ permeable to K⁺ than to Na⁺.