NE203 Exam 1

Patch Clamp Method

A technique capable of measuring the currents flowing through single channels

Which technique uses event-related potentials to evaluate brain activity? Transcranial magnetic stimulation Magnetic resonance imaging Electroencephalography X-rays Computerized tomography

Electroencephalography

Which statement best describes the action potential? An action potential occurs when the cell's membrane potential reaches threshold. The level of depolarization is graded in proportion to the magnitude of the stimulus. An action potential is specialized to transmit signals over only very short distances. An action potential is elicited by hyperpolarization. An action potential is a brief change in membrane potential from positive to negative.

An action potential occurs when the cell's membrane potential reaches threshold.

There are _______ broad families of receptor proteins. 2 hundreds of 3 dozens of 5

2

Which statement about myelination is false? Sodium and potassium channels are clustered at the nodes of Ranvier. Myelin serves to sharply increase the time constant of the axon. Multiple layers of closely opposed glial membranes wrap the axon and serve as an electrical insulator. Myelin is absent at the nodes of Ranvier. Myelin sheaths are created by glial cells.

Myelin serves to sharply increase the time constant of the axon.

In a two-compartment model of a cell with a K+-permeable membrane and a 10-fold excess of K+ in the inside compartment, how would the membrane potential change if all K+ ions were replaced by Na+ ions? It would double. It would be reduced by half. No potential would be generated. It would not change. It would become positive.

No potential would be generated.

A mouse model is created through Cre/lox technology in which a gene is knocked out of the central nervous system only. Which region would continue to express the gene? Cerebral hemispheres Spinal nerves Cerebellum Diencephalon Brainstem

Spinal nerves

Which phenomenon explains the unidirectional propagation of action potentials? The voltage dependence of the sodium channels. The voltage dependence of the potassium channels. Sufficient "leakiness" of the axons, such that backward propagation of action potentials is prevented. The presence of a refractory period at a location where an action potential has just passed. The polarized orientation of microtubules within the axon.

The presence of a refractory period at a location where an action potential has just passed.

True or false: In a two-compartment model of a cell with 10 times more KCl inside than outside and a chloride-permeable membrane separating these two compartments, the transmembrane potential (inside relative to outside) would be positive at electrochemical equilibrium. Responses

True

The _______ most directly affects the rate of information processing within the central nervous system. threshold voltage of neurons. propagation speed of action potentials. number of sodium channels along an axon. number of potassium channels along an axon. ratio of sodium to potassium channels.

propagation speed of action potentials.

At equilibrium, when the neuron is at rest

the concentration of K+ ions is higher inside the cell, but the diffusion force driving K+ ions out of the cell is balanced by an electrical force keeping K+ from leaving the cell.

The resting membrane potential typically ranges from _______ to _______. 40 mV; 90 mV −40 mV; −90 mV −90 mV; 90 mV 40 V; 90 V 0 mV; 90 mV

−40 mV; −90 mV

In voltage clamp experiments, the early current will disappear if the membrane is clamped at _______ mV.

+52

Hodgkin and Katz discovered that the resting membrane potential changes by up to _______ mV per tenfold change in K+ concentration. +58 +65 +119 +90 +29

+58

If the distribution of EPP amplitudes has peaks at 0.4 mV, 0.8 mV, 1.2 mV, 1.6 mV, and 2.0 mV, what is the most likely amplitude of the MEPP? 0.4 mV 1.6 mV 1.2 mV 2.0 mV 0.8 mV

0.4mV

Listed below are the individual events that make up chemical synaptic transmission.1. Diffusion of transmitter across the synaptic cleft.2. Depolarization of the presynaptic terminal.3. Vesicle fusion with plasma membrane.4. Opening of voltage-gated ion channels.5. Activation of presynaptic, calcium-sensitive proteins.Which sequence represents the correct ordering of these events? 1; 2; 4; 5; 3 2; 4; 5; 3; 1 2; 5; 4; 3; 1 1; 2; 3; 4; 5 5; 4; 2; 3; 1

2; 4; 5; 3; 1

During the overshoot phase of an action potential, membrane potential briefly reaches a value near _______ mV. −80 −65 0 50 90

50

Approximately _______% of human genes is expressed in the nervous system.

85

Which observation was not observed in Hodgkin and colleagues' voltage-clamp study of squid action potentials? A sustained outward current as a result of hyperpolarization. Capacitive currents in response to depolarizing voltage steps. Capacitive currents in response to hyperpolarizing voltage steps. A delayed outward current as a result of depolarization. A transient inward current as a result of depolarization.

A sustained outward current as a result of hyperpolarization.

Which treatment would prevent the release of neurotransmitter from the presynaptic terminal? Monoamine oxidase inhibitor Acetylcholinesterase Potassium channel blocker A toxin that cleaves synaptobrevin AMPA antagonist

A toxin that cleaves synaptobrevin

Which is the key event at a membrane potential of 0 mV?

The early current is at its maximum

Which statement does not stem from the application of Ohm's law to ionic conductances? The calculations stemming from Ohm's law can be used to derive a mathematical description of the action potential. The driving force on the ionic current is the difference between the membrane potential and the ion's Nernst potential. All permeant ions experience an identical driving force at each time point during the course of an action potential. The conductance for each ion can be calculated based on the measured ionic currents and the calculated driving force. The conductance for an ion is inversely proportional to the resistance of the membrane to the passage of that ion.

All permeant ions experience an identical driving force at each time point during the course of an action potential.

Which is not integral to the action potential waveform? A transient increase in the sodium current A change in permeability of the membrane to sodium A change in permeability of the membrane to potassium A "self-activating" aspect to the rise in the sodium current An initial decrease in the potassium current

An initial decrease in the potassium current

Which is not integral to the action potential waveform? An initial decrease in the potassium current. A change in permeability of the membrane to sodium. A change in permeability of the membrane to potassium. A transient increase in the sodium current. A "self-activating" aspect to the rise in the sodium current.

An initial decrease in the potassium current.

What physical characteristic distinguishes neurons from other types of cells?

Axon

The brain imaging technique that makes use of a narrow X-ray beam is called Responses PET. CT. MRI. fMRI. SPECT.

CT.

You conduct a voltage clamp experiment in which you hold the presynaptic terminal of a glutamatergic neuron (a neuron that releases glutamate) at 0 mV. When you treat the terminal with TTX, an inward current is recorded. Which ion and ion channels are responsible for the current you observe? Calcium; voltage-gated calcium channels Sodium; ligand-gated non-specific cation channels Calcium; ligand-gated non-specific cation channels Sodium; voltage-gated sodium channels Potassium; voltage-gated potassium channels

Calcium; voltage-gated calcium channels

The recycling of synaptic vesicles is tracked using HRP as a vesicle marker. What will be the observed sequence of HRP movement? Endosome, coated vesicle, vesicle reserve pool Coated vesicle, endosome, vesicle reserve pool Vesicle reserve pool, coated vesicle, endosome Endosome, vesicle reserve pool, coated vesicle Coated vesicle, vesicle reserve pool, endosome

Coated vesicle, endosome, vesicle reserve pool

What would occur if the ATPase pumps in a neuron stopped functioning? Concentration gradients would not be maintained across the membrane. At rest, potassium would continuously depolarize the cell. During the action potential, the sodium channel would not inactivate. During the action potential, the voltage-gated ion channels would remain closed. At rest, sodium would continuously depolarize the cell.

Concentration gradients would not be maintained across the membrane.

Which structural features are not shared by all active transporters? Conformational changes associated with ion translocation Ion binding sites ATP binding sites Transmembrane helices All of the above

Conformational changes associated with ion translocation

Which structure can be found exclusively at an electrical synapse? Synaptic vesicle Connexon Neurotransmitter receptor Synaptic cleft Presynaptic membrane

Connexon

Which structure can be found exclusively at an electrical synapse? Synaptic vesicle Connexon Presynaptic membrane Neurotransmitter receptor Synaptic cleft

Connexon

Which form of genetic engineering involves the insertion or deletion of a specific gene at a specific site within the genome?

Creating knock-in or knock-out mice

Which channel is a sensor of membrane curvature? AMPA receptor TRPV1 CLC1 Piezo Cyclic nucleotide-gated channel

Cyclic nucleotide-gated channel

What effects would treatment of a squid giant axon with tetraethylammonium have on the voltage-dependent K+ conductance?

Decrease K+ conductance magnitude

Which of the following was observed in studies measuring the efflux of radioactive sodium from the squid giant axon? No recovery when potassium or ATP was restored. Dramatic increase of efflux during a brief train of action potentials. Dependence of efflux upon the presence of ATP. Decrease of efflux when ATP synthesis was increased. Sharp drop in efflux when intracellular potassium was removed.

Dependence of efflux upon the presence of ATP.

Although Na+ and K+ conductances have a similar dependence on membrane potential, Na+ and K+ currents exhibit very different dependence on membrane potential. This dichotomy arises from

Differences in the electrochemical driving force acting on Na+ and K+

A scientist wishes to develop a new drug that prevents synaptic communication via neuropeptides but not small molecule neurotransmitters. Which mechanism would be a good target for his drug? Blocking of voltage-gated sodium channels Increasing levels of synaptotagmin Blocking of voltage-gated calcium channels Disruption of axonal transport Disruption of V-SNARES

Disruption of axonal transport

Which feature distinguishes the four model organisms (mouse, zebrafish, fruit fly, and nematode) from other animals that have been intensively studied by neuroscientists? Extensive and interesting behavioral repertoire. Expression of behaviors is reflex-only (i.e., no complex behaviors). Ease of genetic analysis and manipulation. Nervous system of substantial complexity. Specific neural structures or behaviors of interest.

Ease of genetic analysis and manipulation.

Which of the following techniques is not used to study neural circuits? Optogenetics Electron microscopy Genetic engineering Fluorescence microscopy Calcium imaging

Electron microscopy

Which technique first produced unequivocal support for the neuron doctrine of the nervous system (as opposed to the reticular theory)? Acetylcholinesterase staining. EEG (electroencephalogram). Electron microscopy of nervous tissue. Calcium imaging. Extracellular electrical recordings

Electron microscopy of nervous tissue.

Which statement is a common, defining feature of membrane-bound active ion transporters? All are electrogenic. All move sodium across the membrane. All catalyze the conversion of ATP to ADP. All are able to move at least one ion against its concentration gradient. All transport two or more different ions.

All are able to move at least one ion against its concentration gradient.

In the operation of sodium-potassium ATPase, there is an obligatory coupling of sodium efflux and potassium influx. this transporter (or "pump") is electrogenic. phosphorylation and dephosphorylation respectively, are associated with the sodium and potassium transport steps. the pump transports two potassium ions for every three sodium ions. All of the above

All of the above

Animal toxins have been discovered that block sodium channels. prolong the open state of sodium channels. alter the voltage-dependence of sodium channels. block potassium channels. All of the above

All of the above.

Which observation would indicate a role for calcium in transmitter secretion? Observation of presynaptic depolarizing currents after blockade of sodium channels. Voltage clamp experiments showing voltage-gated calcium channels in the presynaptic terminal. Induction of transmitter release by injection of calcium into the presynaptic terminal. Blockade of transmitter release by injection of calcium blocker into the presynaptic terminal. All of the above.

All of the above.

Based on the observations made by Hodgkin and Huxley, one can expect ion channels to allow ions to move across the membrane quickly. use electrochemical gradients to pass ions. exist in distinct variants, allowing different types of ions to pass. respond to changes in the membrane potential. All of the above

allow ions to move across the membrane quickly. use electrochemical gradients to pass ions. exist in distinct variants, allowing different types of ions to pass. respond to changes in the membrane potential.

The main anatomical difference between ganglion of the sympathetic and parasympathetic nervous systems is that the ganglion of the sympathetic nervous system is located _______, whereas that of the parasympathetic nervous system is located _______.

along the outside of the spinal cord; in or around the organs they innervate

The amplitude of the action potential of a given neuron is smaller if the resting potential of the neuron is lower. related to the number of synapses on the neuron. dependent on the magnitude of the sensory stimulus. always the same. larger in response to depolarizing currents of greater magnitude.

always the same.

When a muscle fiber is held at a voltage of 0 mV at the neuromuscular end plate, acetylcholine no longer produces a current because the acetylcholine receptor channels all close instantly at 0 mV. an influx of sodium is balanced by an equal efflux of potassium. the membrane conductance for each permeant ion is 0 at 0 mV. at 0 mV, the potassium ions lodge in the receptor channel and block the influx of sodium. the Nernst potentials for both sodium and potassium are 0 mV in muscle fibers.

an influx of sodium is balanced by an equal efflux of potassium.

Structures that form the voltage sensors of K+ channels are embedded in the cell membrane but extend into the extracellular space when the membrane is depolarized. extend into the extracellular space. are located within the channel pore. extend into the intracellular space. are embedded in the cell membrane.

are embedded in the cell membrane.

The resting potential of a cell is negative because there is an excess of K+ outside of the cell at rest. at rest there is an excess of K+ inside the cell, but the membrane is permeable to all ions. at rest there is an excess of K+ inside the cell, and the membrane is permeable chiefly to K+. at rest there is an excess of K+ outside of the cell, and the membrane is permeable chiefly to K+. there is an excess of Cl− ions outside of the cell at rest.

at rest there is an excess of K+ inside the cell, and the membrane is permeable chiefly to K+.

The paddle-like, charged transmembrane domains of potassium channels may dehydrate the ions as they cross the membrane. be the primary voltage sensors. serve as a plug or inactivation gate. enable the aggregation of channel subunits into functional channels. confer ion selectivity to the channel.

be the primary voltage sensors.

Miniature end plate potentials, or MEPPs, are produced by the smallest neurotransmitters. in response to weak stimuli. by the smallest axons. by spontaneous release of neurotransmitter. at miniature end plates.

by spontaneous release of neurotransmitter.

An advantage that intracellular recordings have over extracellular recordings is that they can alter the threshold potential. are easier to obtain. can be obtained in many more parts of the nervous system. can record synaptic and receptor potentials. can record from many neurons at once.

can record synaptic and receptor potentials.

White matter tracts that connect the two hemispheres are called

commissures.

Studies of the ionic basis of the action potential in squid giant axon found that manipulating sodium has large effects on both the size of the action potential and the resting membrane potential. decreasing sodium outside the cell increases the size of the action potential. decreasing potassium outside the cell increases the size of the action potential. decreasing sodium outside the cell decreases the size of the action potential. decreasing potassium outside the cell decreases the size of the action potential.

decreasing sodium outside the cell decreases the size of the action potential.

Voltage clamp data, in which investigators analyzed membrane conductances during action potentials, showed all of the following except depolarization leads to a time-dependent inactivation of the potassium current. depolarization leads to a time-dependent inactivation of the sodium current. the sodium current was rapidly activated by depolarization. the potassium current activates on a comparatively slow time scale of a few ms. at certain potentials, there can be zero current even with a large conductance.

depolarization leads to a time-dependent inactivation of the potassium current.

An action potential occurs if current injected into a neuron _______ the neuron to reach _______ potential. hyperpolarizes; resting hyperpolarizes; threshold depolarizes; synaptic hyperpolarizes; synaptic depolarizes; threshold

depolarizes; threshold

Which statement regarding membrane potential and equilibrium potential is true? Both membrane and equilibrium potentials change during an action potential. Equilibrium potential is affected by the concentration and electrical gradients of one ion; membrane potential is affected by gradients of all ions. Membrane potential is affected by ion concentration in- and outside of the cell; equilibrium potential is affected only by ions inside the cell. Equilibrium potentials are affected by membrane permeability; membrane potentials are not. Equilibrium potentials are the same for all neurons; membrane potentials can be different depending on the neuron.

Equilibrium potential is affected by the concentration and electrical gradients of one ion; membrane potential is affected by gradients of all ions.

Which is used to study connectivity and identity of neurons?

Fluorescence labeling Radioactive tracing Transgenic induction Antibody labeling

Which structure is employed by many types of channels to couple sensor activation to channel opening? Pore loops Helical linker Ligand-binding domain Water-filled cavity All of the above

Helical linker

The capability of a nerve terminal to rapidly and dramatically produce very large changes in calcium levels is most dependent on the presence of calcium-selective ion channels. enormous gradient of calcium across the membrane. fact that calcium is a positively charged ion. fact that calcium is a divalent cation. All of the above are essential for producing large, rapid concentration changes.

enormous gradient of calcium across the membrane.

SNARE proteins participate in vesicle exocytosis by pushing vesicles from the reserve pool into the docked pool. linking calcium channels to exocytotic fusion sites. forming a protein coat that maintains the vesicle's integrity. binding calcium and then forming a pore into the vesicle. forming a protein complex that pulls the vesicle membrane against the plasma membrane.

forming a protein complex that pulls the vesicle membrane against the plasma membrane.

The bacterial K+ channel studied by Rod MacKinnon is made up of _______, each of which contains helical membrane-spanning domains with a _______ between them. two domains; selectivity filter four subunits; pore loop two subunits; pore loop two subunits; pore four subunits; pore helix

four subunits; pore loop

Nodes of Ranvier represent gaps in myelin wrapping. segments of axon where passive current flows. areas of high synaptic density. points where two axons connect. segments of axon where only K+ channels are located.

gaps in myelin wrapping.

The TRP ion channel family includes channels responsive to heat and cold. intracellular cyclic nucleotides. complex sequences of voltage commands. ultraviolet light. hyperpolarization.

heat and cold.

During the knee jerk reflex, the role of the spinal interneuron is to _______ the _______ muscle, allowing the leg to _______. inhibit; flexor; extend inhibit; extensor; extend inhibit; extensor; flex inhibit; flexor; flex activate; flexor; extend

inhibit; flexor; extend

Injecting hyperpolarizing current into an axon causes only passive current flow because it brings the membrane potential farther away from the threshold it does not generate an action potential it cannot spread more than a few millimeters all of the above none of the above

it brings the membrane potential farther away from the threshold it does not generate an action potential it cannot spread more than a few millimeters

The main function of the nervous system is communication. Anatomically, the cells of the nervous system accomplish this using.. synapses. neurotransmitters. long axons and shorter dendrites. pyramid-shaped somas. glia cells.

long axons and shorter dendrites.

The synaptic potential propagates along axons. makes communication between nerve cells possible. results in a long-term change in a cell's membrane potential. determines the cell's resting potential. occurs only in response to external stimuli.

makes communication between nerve cells possible.

Ion channels that respond to mechanical displacement are called voltage-gated. ligand-gated. mechanosensitive. thermosensitive. All of the above

mechanosensitive.

Ion channels can be gated by which of the following types of stimuli? membrane depolarization. chemical signals. mechanical forces. heat. All of the above

membrane depolarization. chemical signals. mechanical forces. heat.

The voltage clamp method controls the _______ at any desired level. Na+ current amplitude of an action potential frequency of an action potential membrane potential K+ current

membrane potential

Which glial cell is the CNS version of the immune system? Schwann cells. Oligodendrocytes. Astrocytes. Stem cells. Microglia.

microglia.

The ability of K+ channels to allow K+ to selectively diffuse across the membrane, down their electrochemical gradient, is due to negative charges that attract K+. a water-filled cavity. a selectivity filter that is optimal to fit dehydrated K+ ions. the simultaneous presence of multiple K+ ions. All of the above

negative charges that attract K+. a water-filled cavity. a selectivity filter that is optimal to fit dehydrated K+ ions. the simultaneous presence of multiple K+ ions.

Which binds only at the extracellular domain of a ligand-gated ion channel? Ca2+ cGMP Na+ cAMP Neurotransmitter

neurotransmitter.

In a two-compartment model of a cell with a K+-permeable membrane, at the K+ equilibrium potential, there is _______ flux of K+ ions. a small outward a small inward a large outward a large inward no net

no net flux

Where will voltage-gated Na+ channels be most abundant?

nodes of ranvier

Myelin is provided by _______ in the CNS and by _______ in the PNS. oligodendrocytes, Schwann cells pyramidal cells, Schwann cells pyramidal cells, oligodendrocytes Schwann cells, oligodendrocytes astrocytes, oligodendrocytes

oligodendrocytes, Schwann cells

The resting potential of a neuron is due primarily to

open K+ channels.

Which technique combines transgenics with neural stimulation to characterize the properties and behaviors of neurons? Recording from sensory neurons Fluorescence imaging Calcium imaging Recording from motor neurons Optogenetics

optogenetics.

Subthreshold current injected into an axon flows _______ along the axon and _______ with distance from the site of injection. passively; remains constant actively; remains constant actively; grows actively; decays passively; decays

passively; decays

A topographical map is a

point-to-point correspondence between the sensory receptive field and the neurons in the spinal cord, thalamus and sensory cortex that are stimulated by it.

At rest, the interior of a neuron is negatively charged relative to the exterior. This negative charge is due mainly to

proteins.

The calcium ATPase is unique among transporters in that its pumping action involves no conformational changes. is much simpler than the sodium-potassium pump because it has only three transmembrane regions. uses the same intracellular domain for both nucleotide binding and ion translocation. pumps 15 calcium ions for each molecule of ATP consumed. pumps calcium in a cyclical process that utilizes energy from ATP.

pumps calcium in a cyclical process that utilizes energy from ATP.

Which is the sensory receptor in the myotactic reflex arc? Spinal cord interneurons Biceps femoris (hamstring muscle) Quadriceps muscle Dorsal root ganglion Ventral horn neurons

quadriceps muscle.

The current flowing through individual ion channels reflects the passage of thousands of ions per millisecond. has a different reversal potential than the macroscopic ionic current has. has a different voltage dependence than the macroscopic ionic current has. exhibits the same time course across all individual sodium channels. was visualized with the advent of the voltage clamp in 1956.

reflects the passage of thousands of ions per millisecond.

A neuron that innervates (i.e., makes synaptic contact with) a large number of other neurons can fire only at very low frequencies. represents massive neural integration. must fire at very high frequencies to be useful. represents divergent neural signaling. represents convergent neural signaling.

represents divergent neural signaling.

Calcium imaging takes advantage of the fact that this ion is involved in second messenger signaling. firing of action potentials. neuronal activity. firing of graded potentials. All of the above

second messenger signaling. firing of action potentials. neuronal activity. firing of graded potentials.

Which statement best describes the electrical properties of nerve cells? Responses They are unable to conduct electricity under any circumstances. They are exceptionally good conductors of electricity (much better than copper wires). They are similar in their electrical conduction properties to copper wires. They are electron sinks; they absorb many electrons, but no electricity comes out of them. In comparison to copper wires, they are relatively poor conductors of electricity.

In comparison to copper wires, they are relatively poor conductors of electricity.

The narrowest part of a channel pore is called the pore loop. selectivity filter. water-filled cavity. ion selector. pore helix.

selectivity filter.

During the myotactic reflex, graded potentials are fired by all of the following, except flexor motor neuron. None of the above sensory neuron. interneuron. extensor motor neuron.

sensory neuron.

A surprising result that emerged from the molecular and genetic analysis of ion channels was the sheer number of different ion channels. voltage-dependence of the ion channels. time-dependence of the ion channels. discovery of differences in ionic selectivity. size of the individual ion channels.

sheer number of different ion channels.

Which statement about the ionic permeability of cell membranes is true? In resting nerve cells, the membrane is quite permeable to potassium. The permeability of ions is constant over time. In resting nerve cells, the membrane is permeable to all ions. In resting nerve cells, the membrane is quite permeable to sodium. In resting nerve cells, the membrane is quite permeable to calcium.

In resting nerve cells, the membrane is quite permeable to potassium.

In the sequence of events in chemical synaptic transmission, which event occurs immediately after the action potential arrives at the presynaptic terminal?

Influx of Ca2+ into the presynaptic terminal

The figure shows an electron micrograph of a chemical synapse in the cerebral cortex. Which statement about this synapse is accurate? Packaging of the neurotransmitter Fusion of the synaptic vesicles with the presynaptic membrane Release of the neurotransmitter Delivery of the neurotransmitter to the presynaptic terminal Influx of Ca2+ into the presynaptic terminal

Inside the presynaptic neuron are synaptic vesicles, which fuse with the membrane in the active zone.

Which of the following is not an established role for glial cells? Assisting synaptic transmission via neurotransmitter uptake. Hastening the propagation of neural impulses. Maintaining the ionic milieu surrounding nerve cells. Integrating information to assist neural computation. Providing scaffolds that assist neural development.

Integrating information to assist neural computation.

Which current is produced in response to a hyperpolarizing stimulus in a giant axon of a squid? Transient inward current Outward capacitive current Inward capacitive current Prolonged outward current Delayed outward current

Inward capacitive current

Which statement regarding metabotropic and ionotropic receptors is true? Ionotropic receptors require the activation of intracellular messengers. Metabotropic and ionotropic receptors act via the same mechanisms; the difference is the neurotransmitters that activate them. Metabotropic receptors open channels faster than ionotropic receptors do. Ionotropic receptors have immediate effects; metabotropic receptors produce long-term effects. Both directly allow ion flow through an ion pore in the receptor.

Ionotropic receptors have immediate effects; metabotropic receptors produce long-term effects.

Which substances diffuse through connexon channels between pre- and postsynaptic neurons? Ions Second messengers Small peptides ATP All of the above

Ions Second messengers Small peptides ATP

Which statement about a center-surround receptive field is false? It can involve an excitatory response (e.g., to touch). It can be mapped by electrophysiological recording techniques. It can involve an inhibitory response (e.g., to touch). It is characterized by a circular center and a doughnut-shaped surround. It is found only in primary sensory cortex.

It is found only in primary sensory cortex.

Which statement about electrochemical equilibrium is true? For a given ion concentration gradient, the resulting potential is independent of the number of charges on the ion. The fluxes of ion that are required to generate the membrane potential disrupt chemical electroneutrality. The size of the potential is inversely proportional to the size of the ion gradient. It occurs when the potential across the membrane exactly offsets the concentration gradient. It involves the movement of a relatively large number of ions, altering the concentrations of permeant ions.

It occurs when the potential across the membrane exactly offsets the concentration gradient.

The decrease in size of individual quanta observed in familial infantile myasthenia is consistent with the observation of a change in the sensitivity of the calcium release mechanism compared with healthy controls. a greater rate of spontaneous exocytosis depleting the size of the vesicle pool, than in healthy controls. a loss of all ACh receptors at the neuromuscular junction. smaller synaptic vesicles compared with healthy controls. fewer calcium channels in the presynaptic terminals compared with healthy controls.

smaller synaptic vesicles compared with healthy controls.

The technique that first revealed the tremendous diversity of neuronal cell types, by revealing different cell bodies along with their processes, is fluorescence staining. electron microscopy. cresyl violet staining. the Nissl stain. the Golgi technique (stain).

the Golgi technique (stain).

Gap junctions may exhibit all of the following features except the ability to pass electrical current unidirectionally. the ability to synchronize the activity of populations of nerve cells. the ability to pass electrical current bidirectionally. the ability to amplify small incoming electrical signals into large regenerative potentials. the ability to pass small metabolites, including some second messengers.

the ability to amplify small incoming electrical signals into large regenerative potentials.

When current is injected into an axon the current will spread in only one direction. the current will spread passively only if it is a depolarizing current. an action potential is evoked before the current has spread any distance from the point of injection. the current will propagate as an oscillating wave independently of its polarity. the current will decay exponentially with increasing distance from the injection site (if no action potential is present).

the current will decay exponentially with increasing distance from the injection site (if no action potential is present).

Which statement best describes the Nernst equation? It relates the equilibrium potential of an ion to its intracellular concentration. It relates the equilibrium potentials of multiple ions to their intra- and extracellular concentrations. It relates the equilibrium potential of an ion to its intra- and extracellular concentrations. It relates the equilibrium potential of an ion to its extracellular concentration. It relates the equilibrium potentials of multiple ions to their intracellular concentrations.

It relates the equilibrium potential of an ion to its intra- and extracellular concentrations.

Which statement about multiple sclerosis (MS) is false? It was recently proven that all cases of MS are due to persistent infection by a tropical parasite. Cases of MS vary considerably in terms of severity and progression of the illness. It is characterized by demyelination of axons along with some axon loss. Symptoms of MS may include weakness, paralysis, double vision, monocular blindness, and abnormal somatic sensations. Magnetic resonance imaging can help diagnose some cases of MS.

It was recently proven that all cases of MS are due to persistent infection by a tropical parasite.

How would application of a Ca2+ channel blocker affect the function of a chemical synapse? It would increase the magnitude of the presynaptic action potential. It would eliminate the postsynaptic potential and the presynaptic Ca2+ current. It would increase the magnitude of postsynaptic potential. It would eliminate the postsynaptic potential but have no effect on the presynaptic neuron. It would eliminate the presynaptic Ca2+ current but have no effect on the postsynaptic potential.

It would eliminate the postsynaptic potential and the presynaptic Ca2+ current.

The squid giant axon is useful in neuronal studies because its axon is easy to penetrate with recording electrodes because it is so long. its giant ion channels allow the insertion of recording electrodes into the channels. the axon has fewer ion channels, which simplifies the analysis of observations. the cytoplasm in the axon can be extruded, thus allowing studies of its composition. multiple synapses between the nerve cells make them easy to study.

the cytoplasm in the axon can be extruded, thus allowing studies of its composition.

The transmembrane concentration gradient of which ion has the greatest effect on the resting membrane potential? Cl− K+ PO43− Ca2+ Na+

K+

Hodgkin and Katz proposed that sodium was the predominant ion associated with the firing of an action potential because sodium ions can move more quickly than other ionic species. the membrane potential approaches the Na+ Nernst potential during the falling phase. the membrane potential approaches the Na+ Nernst potential during the rising phase. sodium ions are the only ions that can flow into the nerve cell body. the sodium gradient explains the rising phase, falling phase, and overshoot of the action potential.

the membrane potential approaches the Na+ Nernst potential during the rising phase.

The amplitude of an action potential measured at one end of an axon will be _______ in comparison to an action potential measured at the other end of the axon. the same size smaller virtually insignificant larger sometimes smaller and sometimes larger

the same size

The structural brain imaging technique that relies on atoms behaving like small magnets is called EEG. CT. PET. SPECT. MRI.

MRI.

Which technique provides detailed anatomical data on the brain? Magnetic resonance imaging Electroencephalography Analysis of event-related potentials Transcranial magnetic stimulation X-rays

Magnetic resonance imaging

Which type of magnetic resonance imaging (MRI) is superior in revealing neural activity? Functional MRI (fMRI) Blood oxygenation-level dependent (BOLD) Magnetic source imaging (MSI) Magnetoencephalography (MEG) Diffusion tensor imaging

Magnetoencephalography (MEG)

In familial hemiplegic migraine, the underlying mutation in a calcium channel causes enhanced synaptic excitation of second-order pain sensitive neurons. the syndrome by some unknown mechanism. abnormally functioning pain receptors in the peripheral nervous system. abnormal activation of neocortical pain centers. abnormal activation of thalamic pain centers.

the syndrome by some unknown mechanism.

Ionic and capacitive currents measured by the voltage clamp method differ in their time course. dependence on ion channels. voltage dependence. All of the above None of the above

time course. dependence on ion channels. voltage dependence.

The most important factor determining whether a receptor-operated ion channel is inhibitory or excitatory is the ligand-binding properties of the receptor. whether the permeant ion is positively or negatively charged. whether the permeant ion's reversal potential is positive or negative to threshold. the number of different ions that can pass through the receptor. None of the above

whether the permeant ion's reversal potential is positive or negative to threshold.

In an experiment, you measure the resting membrane potential of a neuron using two electrodes: one is inserted inside the axon and the other is inserted outside, serving as the reference electrode. Then you add a drug that binds to sodium channels in the membrane and opens the channels. With what you know about ion concentrations inside and outside the cell, what measurements might be expected before and just after the drug is applied?

−65 mV before; +40 mV after the drug

How does membrane permeability to K+ (PK) and Na+ (PNa) change during an action potential? PK exceeds PNa at rest; PNa temporarily increases during the action potential. PNa always exceeds PK; permeability does not change for either ion. PNa exceeds PK at rest; PK temporarily increases during the action potential. PK always exceeds PNa; permeability does not change for either ion. PK exceeds PNa at rest; PNa increases during the action potential and remains higher than PK until the next action potential, then it quickly drops.

PK exceeds PNa at rest; PNa temporarily increases during the action potential.

How does membrane permeability to K+ (PK) and Na+(PNa) change during an action potential? PK exceeds PNa at rest; PNa temporarily increases during the action potential. PK always exceeds PNa; permeability does not change for either ion. PNa always exceeds PK; permeability does not change for either ion. PNa exceeds PK at rest; PK temporarily increases during the action potential. PK exceeds PNa at rest; PNa increases during the action potential and remains higher than PK until the next action potential, then it quickly drops.

PK exceeds PNa at rest; PNa temporarily increases during the action potential.

Which is not a function of astrocytes? Regulating the amount of circulating ions Help form the blood-brain barrier Regulating the amount of circulating neurotransmitters Secrete chemicals known to promote synapse formation Promote the birth of new neurons in cases of chemical or physical damage

Promote the birth of new neurons in cases of chemical or physical damage

Which type(s) of electrical signals occur(s) within the neural circuit for a spinal reflex? Synaptic potential only Receptor potential only Receptor potential, synaptic potential, and action potential Action potential only Receptor potential and action potential only

Receptor potential, synaptic potential, and action potential

Which treatment was shown to eliminate the early inward current in squid giant axons? Doubling of external sodium. Removal of all external cations. Removal of external sodium. Doubling of external potassium. Removal of external potassium.

Removal of external sodium.

Which intervention will disrupt the function of the Na+/K+ ATPase pump? Removal of extracellular ATP Removal of extracellular K+ Application of tetrodotoxin Removal of extracellular Na+ Removal of cytoplasmic Ca2+

Removal of extracellular K+

A doctor taps the right knee in an individual who was in a car accident and has sustained damage to the right dorsal root of the lower spinal cord. Which motor response would you expect? Left leg extends. Right leg extends. Left leg flexes. Right leg remains motionless. Right leg flexes.

Right leg remains motionless.

During which phase of an action potential does membrane permeability to Na+ exceed membrane permeability to K+? Overshoot phase only All of the phases of the action potential Rising and overshoot phases Overshoot and falling phases Rising phase only

Rising and overshoot phases

Which evidence supports the assertion that the macroscopic Na+ current is the sum of many microscopic Na+ currents? The probability of a Na+ channel opening increases as the membrane is hyperpolarized. The averaged collective response of single channels resembles the time course of the macroscopic current. Opening and closing of Na+ channels is concentration-dependent. Tetrodotoxin blocks macroscopic, but not microscopic, currents. All of the above

The averaged collective response of single channels resembles the time course of the macroscopic current.

Which ligand-gated ion channel is regulated primarily by an intracellular signal? Glutamate receptor. The potassium-activated calcium channel. The acid-sensing ion channels. The cAMP- and cGMP-gated ion channels. The glutamate receptor.

The cAMP- and cGMP-gated ion channels.

A neuron has received enough stimulation to fire an action potential; it also has been treated with TEA, a K+ channel blocker. Which outcome is possible? The cell will initially depolarize and will continue to do so until the cell reaches the equilibrium potential for Na+. There will be no change in membrane potential in the cell initially, but will it depolarize after a delay. There will be no change in membrane potential in the cell. The cell will initially depolarize, but repolarization will take much longer because it relies only on ion pumps. The cell will initially hyperpolarize and will return to resting membrane potential after a delay.

The cell will initially depolarize, but repolarization will take much longer because it relies only on ion pumps.

Which statement on the rising or overshoot phase of the action potential is true? The degree of depolarization is limited in part by the inactivation time course of the potassium current. The degree of depolarization is limited in part by the declining driving force on potassium entry. The time from threshold to maximum depolarization is essentially instantaneous (i.e., too fast to be measured accurately with current electronics). The degree of depolarization is limited in part by the inactivation time course for the sodium current. A negative feedback loop leads to a regenerative depolarization that would increase continuously if unchecked.

The degree of depolarization is limited in part by the inactivation time course for the sodium current.

Which statement about postsynaptic currents at the neuromuscular end plate is false? The end plate potential is due to the opening of thousands or millions of channels. The end plate channels show a regenerative opening pattern that propagates an action potential along the length of the muscle fiber. Acetylcholine can induce openings of ligand-gated ion channels. Depolarizing currents can be recorded from outside-out patches of the postsynaptic membrane. Individual channels tend to stay open for no more than a few milliseconds.

The end plate channels show a regenerative opening pattern that propagates an action potential along the length of the muscle fiber.

A dull probe stimulates a Pacinian corpuscle. An electrode is placed midway down the axon, and action potentials are recorded. After one second, the probe is pushed with greater force. What change will occur in the recording? The height of action potentials will increase. The frequency of action potentials will decrease. The resting membrane potential will increase. The frequency of action potentials will increase. The threshold potential level will increase.

The frequency of action potentials will increase.

A transgenic mouse animal model is created that expresses both the Cre recombinase gene, under control of a promoter for a gene expressed only in muscle fibers, and an androgen receptor with loxP sites around exon 2. How will expression of the androgen receptor protein be altered in the transgenic mouse? The mouse will express increased levels of androgen receptor everywhere in the body. The mouse will express increased levels of androgen receptor in muscle fibers. The mouse will not express androgen receptor in muscle fibers. The mouse will not express androgen receptor in the nervous system. The mouse will not express androgen receptor anywhere in the body.

The mouse will not express androgen receptor in muscle fibers.

Which statement regarding refractory periods is true? They allow neurons to fire an unlimited number of action potentials per unit of time. The refractory period ends when the sodium channels are no longer inactivated. During the refractory period the cell requires a less intense stimulus to reach threshold. The refractory period arises in part due to the decrease in potassium conductance across the membrane. The refractory period arises in part due to the increase in sodium conductance across the membrane.

The refractory period ends when the sodium channels are no longer inactivated.

In a two-compartment model of a cell with a K+-permeable membrane and a tenfold excess of K+ in the inside compartment, how would K+ ions flow across the membrane? They would flow in both directions, but the flow would be negligible. They would flow from the inside compartment to the outside compartment. They would flow in both directions at the same time in equal molar quantities. They would flow from the outside compartment to the inside compartment. There would be no flow of K+ ions.

They would flow from the inside compartment to the outside compartment.

Which is used to treat some maladies, such as depression and headaches? Computerized tomography X-rays Transcranial magnetic stimulation Electroencephalography Magnetic resonance imaging

Transcranial magnetic stimulation

Which current corresponds to a flow of Na+ in response to a depolarizing stimulus in a giant axon of a squid?

Transient inward current

To date, which observation is not part of the experimental evidence favoring the vesicular release hypothesis of neurotransmission? Visualization of acetylcholine molecules diffusing out of the neck of the membrane-fused vesicle. Fixed size of MEPPs. Visualization of synaptic vesicles using electron microscopy. Correspondence between a vesicle's acetylcholine content and MEPP size. Quantized distribution of events occurring at the neuromuscular junction.

Visualization of acetylcholine molecules diffusing out of the neck of the membrane-fused vesicle.

For which reason was the development of the voltage clamp critical to investigations of the ionic basis of the action potential? Sodium and potassium currents are activated in non-overlapping voltage regimes. Voltage clamping does not require specialized equipment. Ionic conductances can be activated only in cells that have been voltage clamped. Voltage clamping allows simultaneous control of membrane potential and measurement of permeability changes. Voltage changes in the cell cannot be seen without voltage clamp.

Voltage clamping allows simultaneous control of membrane potential and measurement of permeability changes.

A patient presents with migraines that usually last about 48 hours and are accompanied by vomiting. Two of his immediate relatives show similar symptoms. Which ion channel would you expect to be dysfunctional in this patient? Voltage-gated potassium channel Ligand-gated chloride channel Ligand-gated sodium channel Voltage-gated calcium channel Voltage-gated sodium channel

Voltage-gated calcium channel

Under which circumstances is the Goldman equation equivalent to the Nernst equation? When a membrane is permeable to multiple ions When the membrane is permeable to positively charged ions only When the membrane is permeable to negatively charged ions only When permeability of the membrane is different for different ions When a membrane is permeable to only one ion

When a membrane is permeable to only one ion

Which observation is not evidence that helped to identify sodium as the early current of the action potential? The early current was unaffected by tetraethylammonium. The early current was blocked by tetrodotoxin. The current disappeared near the Nernst potential for sodium. When the late current was blocked, the reversal potential of the inward current shifted to a negative membrane potential. The current declined when there was decreased driving force on sodium fluxes.

When the late current was blocked, the reversal potential of the inward current shifted to a negative membrane potential.

Which statement regarding the diversity of ion channels is false? Sodium channels that do not inactivate have been found. With only six different types, potassium channels are the least diverse channel type. There are least 10 different types of calcium channels. There are at least 10 different sodium channels in humans. Calcium channels serve diverse functions such as influencing action potential shape and mediating the release of neurotransmitters.

With only six different types, potassium channels are the least diverse channel type.

The technique that provides the most direct information about the physical, three-dimensional structure of ion channels is high-performance liquid chromatography. X-ray crystallography. the sequencing of the channel's amino acids. fluorescence imaging of channel subunit dynamics. physiological measurement of ion selectivity.

X-ray crystallography.

Members of the TRP channel family can respond to which of the following stimuli? Capsaicin Heat Mechanical distortion of the plasma membrane All of the above None of the above

Capsaicin Heat Mechanical distortion of the plasma membrane

Which protein plays a key role in endocytosis? Actin Triskelion Clathrin Auxilin Hsc70

Clathrin

Which technique would you use to study the effects of the extracellular environment on ion channel activity? Cell-attached patch clamp. Outside-out patch clamp. Inside-out patch clamp. Conventional voltage clamp. Whole-cell patch clamp.

Outside-out patch clamp

Which is used to edit a genome?

CRISPR-Cas-9

Which factor is important in determining the membrane potential when there are multiple permeant ions? The concentration gradient of the individual ionic species The permeability of the membrane to the individual ionic species The sum total of all of the ions on both sides of the membrane Both a and b All of the above

Both a and b

Which conclusion can be drawn from Hodgkin and Huxley's studies of K+ and Na+ conductances?

Both conductances exhibit the property of time-dependent activation. Both conductances depend on voltage. K+ conductance reaches its maximum with a pronounced delay. Unlike K+ conductance, Na+ conductance reaches its maximum quickly and inactivates rapidly.

Which experimental evidence supports the conclusion that Ca2+ triggers neurotransmitter release from presynaptic terminals? Microinjection of calcium chelators into presynaptic terminals prevents action potentials from causing neurotransmitter secretion. Microinjection of Ca2+ into presynaptic terminals triggers neurotransmitter release even in the absence of presynaptic action potentials. Voltage-gated Ca2+ currents can be detected in presynaptic terminals. Release of neurotransmitters is associated with a rise in Ca2+ concentration within the presynaptic terminal. All of the above

Microinjection of calcium chelators into presynaptic terminals prevents action potentials from causing neurotransmitter secretion. Microinjection of Ca2+ into presynaptic terminals triggers neurotransmitter release even in the absence of presynaptic action potentials. Voltage-gated Ca2+ currents can be detected in presynaptic terminals. Release of neurotransmitters is associated with a rise in Ca2+ concentration within the presynaptic terminal.

Which statement accurately describes the expression of genes in the nervous system? Most of the genes in the human genome are expressed in the CNS. Every gene in the human genome is expressed in the CNS. Splice variants add diversity to brain function via beneficial mutations. The genes that are expressed in the CNS are expressed equally in all neurons. A small subset of the total human genome is expressed in the CNS.

Most of the genes in the human genome are expressed in the CNS.

Which ion is transported down its concentration gradient by ion exchangers? H+ Na+ Cl− Ca2+ All of the above

Na+

There is an excess of _______ in the extracellular compartment, relative to the intracellular compartment. Na+, Cl−, and Ca2+ K+ only Na+ only Na+ and Ca2+ only Na+ and Cl− only

Na+, Cl−, and Ca2+

A friend has taken a job in a neuroscience research lab and is studying neurons in a freshwater snail. He has been told to calculate the equilibrium potential of K+. Which equation will he use and what other information will he need? Nernst equation; concentration of K+ inside and outside of the cell Nernst equation; concentration of K+ inside and outside of the cell and permeability of K+ Goldman equation; concentration of K+ inside and outside of the cell Nernst equation; concentration of K+, Na+, and Cl— inside and outside of the cell Goldman equation; concentration of K+ inside and outside of the cell and permeability of K+

Nernst equation; concentration of K+ inside and outside of the cell

What is the major determinant of the permeability of a membrane to a specific ion? Electrical charge of the ion Number of open ion channels specific for that ion Concentration of the ion outside the cell Size of the ion Concentration of the ion inside the cell

Number of open ion channels specific for that ion

In which way do potassium channels in the squid giant axon differ from sodium channels? The potassium channels open in response to hyperpolarization of the membrane. The summing of the individual potassium channels does not reconstruct the macroscopic current. Once the potassium channels open in response to a voltage step command, they tend to remain open. The potassium channels pass only a few ions per second. The potassium channels show little voltage dependence.

Once the potassium channels open in response to a voltage step command, they tend to remain open.

Which statement about ionic distributions in nerve cells is true? Calcium is higher inside cells than outside cells. Sodium is higher outside cells than inside cells. The concentrations of all ionic species are the same for all nerve cells in all animals. Potassium is higher outside cells than inside cells. Chloride is higher inside cells than outside cells.

Sodium is higher outside cells than inside cells.

What is the function structure C? Location of protein synthesis and cellular machinery Regulates chemical environment for signaling Receives incoming signals from other neurons Regeneration of action potential Speeds up conduction of an action potential

Speeds up conduction of an action potential

True or false? Certain animals, such as pufferfish, cone snails and scorpions, produce neurotoxins that prevent the transient increase in membrane permeability that underlies action potentials. Treating a neuron with such toxins will decrease action potential amplitude.

TRUE

Which statement describes one of the features of Hodgkin and Huxley's mathematical model? The falling phase can be at least partially accounted for by the inactivation of the potassium current. The fast-rising phase can be accounted for by selective potassium entry. The undershoot can be accounted for by the time course of sodium current reactivation. The action potential can be reconstructed based entirely on the time course and amplitudes of the ionic conductances. The model is unable to mimic the experimentally measured refractory period.

The action potential can be reconstructed based entirely on the time course and amplitudes of the ionic conductances.

Which statement correctly differentiates between the passive and active current in a myelinated axon? The passive current flows only in the nodes of Ranvier, unlike the active current. Action potential propagation depends on active current flow only. The passive current flows in one direction along the axon, unlike the active current. The active current flows only in the nodes of Ranvier, unlike the passive current. Action potential propagation depends on passive current flow only.

The active current flows only in the nodes of Ranvier, unlike the passive current.

Which evidence supports the assertion that the macroscopic Na+ current is the sum of many microscopic Na+ currents? The probability of a Na+ channel opening increases as the membrane is hyperpolarized The averaged collective response of single channels resembles the time course of the macroscopic current. Opening and closing of Na+ channels is concentration-dependent. Tetrodotoxin blocks macroscopic, but not microscopic, currents. All of the above

The averaged collective response of single channels resembles the time course of the macroscopic current.

How does the resting membrane potential of a typical neuron compare to the equilibrium potential (calculated by the Nernst equation) for potassium? The resting membrane potential is not exactly equal to the equilibrium potential for potassium because of variation among neurons. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because rapid fluctuations in membrane potential prevent accurate measurements. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because potassium does not contribute to the resting membrane potential. The resting membrane potential is exactly equal to the equilibrium potential for potassium. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because the membrane has some resting permeability to species other than potassium.

The resting membrane potential is not exactly equal to the equilibrium potential for potassium because the membrane has some resting permeability to species other than potassium.

Which process(es) underlie(s) the refractory period? Rapid activation of Na+ conductance The delay in K+ conductance activation The slow time course of turning off K+ conductance and the persistence of Na+ conductance inactivation The persistence of Na+ conductance inactivation The slow time course of turning off K+ conductance

The slow time course of turning off K+ conductance and the persistence of Na+ conductance inactivation

A student new to neuroscience research is practicing recording resting membrane potentials from giant squid axons. During one of the trials, the resting membrane potential, which is normally around —60 mV, measured —15 mV. Which statement best describes what might have occurred during the experiment? The student did not add enough sodium to the extracellular solution. The student added too little potassium and too much sodium to the extracellular solution. The student added too much sodium to the extracellular solution. The student did not add enough potassium to the extracellular solution. The student added too much potassium to the extracellular solution.

The student added too much potassium to the extracellular solution.

Which statement about EPSPs in the central nervous system is true? Their effect in the central nervous system can be nullified by IPSPs. The time between inputs does not affect the ability of EPSPs to summate. The distance between inputs does not affect the ability of EPSPs to summate. They can be hyperpolarizing. They are much larger than end plate potentials.

Their effect in the central nervous system can be nullified by IPSPs.

What is the most convincing evidence that neurotransmitters are released from synaptic vesicles? Synaptic vesicles can fuse with the presynaptic plasma membrane. Synaptic vesicles contain neurotransmitters. There is a correlation between the number of fused synaptic vesicles and the number of quanta in an EPP. Acetylcholine is released in packets, each equivalent to a MEPP. Presynaptic terminals contain spherical synaptic vesicles.

There is a correlation between the number of fused synaptic vesicles and the number of quanta in an EPP.

In an experiment on an animal model in which the synapsin gene is knocked out, you measure the density of synaptic vesicles in the presynaptic terminal within the active zone and outside the active zone in both knockout and control animals. Given what you know about the function of synapsin, what would you expect to find? There will be no difference between knockout animals and controls. There will be more vesicles in the reserve pool in knockout animals than in controls. There will be no vesicles docked in the active zone in knockout animals. There will be no vesicles in the presynaptic terminal in knockout animals. There will be fewer vesicles in the reserve pool in knockout animals than in controls.

There will be fewer vesicles in the reserve pool in knockout animals than in controls.

Which statement about ion channels is true? They move certain ions against the concentration gradient. They move all ions down the concentration gradient. They are selectively permeable to certain ions. They are functionally similar to active transporters. They move all ions against the concentration gradient.

They are selectively permeable to certain ions.

Which of the following is true about synapses?

They are the tiny space into which neurotransmitter is released.

Which statement about active ion transporters is true? They are selectively permeable to certain ions. They are functionally similar to ion channels. They move all ions against the concentration gradient. They move certain ions against the concentration gradient. They allow ion movement down the concentration gradient.

They move certain ions against the concentration gradient.

Which statement about astrocytes is true? They form myelin in the peripheral nervous system. They play a role in the formation of the blood-brain barrier. They produce collagen in the central nervous system. They regulate the chemical environment of the peripheral nervous system. They produce antibodies.

They play a role in the formation of the blood-brain barrier. - correct