Biopsych Final Study Guide
Which of the following is not part of the brain?
Spinal cord
Which of the following is the main reason that the opening of sodium channels causes a very rapid depolarization of most neurons?
The conjunction of the sodium gradient and the negative membrane potential produces a very large driving force on sodium ions.
Which of the following statements about postsynaptic currents at the neuromuscular end plate is false?
The end plate channels show a regenerative opening pattern that propagates an action potential along the length of the muscle fiber.
Which of the following ligand-gated ion channels is (are) not regulated primarily by an intracellular signal?
The glutamate receptor
Which of the following is not considered to be a "model" organism?
The marine snail Aplysia
Which of the following statements about the spread of electrical signals/currents along an axon is false?
The membrane length constant describes how far an action potential can propagate along an axon.
Which of the following explains the unidirectional propagation of action potentials?
The presence of a refractory period at a location where an action potential has just passed
Which of the following statements on either the rising or overshoot phase of the action potential is false?
The time from threshold to maximum depolarization is essentially instantaneous (i.e., too fast to be measured accurately with current electronics).
Which of the following statements about ionic distributions in nerve cells is false?
The total concentration of all ionic species is approximately the same for all nerve cells in all animals.
Which of the following was not one of the features of Hodgkin and Huxley's mathematical model?
The undershoot can be accounted for by the time course of sodium current reactivation
Representation of which of the following is best accomplished using a topographic map?
The visual world
Which of the following statements about action potentials is false?
They are elicited by hyperpolarization.
Which of the following statements about EPSPs in the central nervous system is false?
They are much larger than end plate potentials.
Which of the following is an advantage that intracellular recordings have over extracellular recordings?
They can record synaptic and receptor potentials.
To date, which of the following 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
For which of the following reasons was the development of the voltage clamp critical to investigations of the ionic basis of the action potential?
Voltage clamping allows simultaneous control of membrane potential and measurement of permeability changes.
Which of the following is not an observation that helped to identify sodium as the early current of the action potential?
When the late current was blocked, the reversal potential of the inward current shifted to a negative membrane potential.
Which of the following statements regarding the diversity of ion channels is false?
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
X-ray crystallography
The differential release of small, clear vesicles, versus large, dense-core vesicles, is best explained by
a more delocalized calcium signal generated by intense neural stimulation.
Neurons exhibit a threshold above which an action potential is triggered because of
a positive feedback loop between depolarization and sodium current activation
The proteins that establish ionic gradients are called
active transporters
Gap junctions may exhibit all of the following features except for the ability to
amplify small incoming electrical signals into large regenerative potentials.
When a muscle fiber is held at a voltage of 0 mV at the neuromuscular end plate, acetylcholine no longer produces a current because
an influx of sodium is balanced by an equal efflux of potassium
Listed below are the individual events that make up chemical synaptic transmission:
b; d; e; c; a Depolarization of the presynaptic terminal Opening of voltage-gated ion channels Activation of presynaptic, calcium-sensitive proteins Vesicle fusion with plasma membrane Diffusion of transmitter across the synaptic cleft
Paddle-like, charged transmembrane domains of potassium channels may
be the primary voltage sensors.
Miniature end-plate potentials, or MEPPs, are produced
by spontaneous release of neurotransmitter.
Typically, neurons firing action potentials encode a signal's intensity by
changing the frequency of their action potentials.
Black widow spider venom is thought to disrupt the functioning of nerve terminals by
circumventing the calcium-regulatory step of exocytosis to promote massive exocytosis.
Studies of the ionic basis of the action potential in squid giant axon found that
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
Activating end plate acetylcholine receptor channels produces 0 current at 0 mV, but is still able to elicit action potentials in muscle fibers because
depolarization of the membrane to 0 mV is sufficient to bring nearby membrane regions, which contain voltage-gated sodium channels, to threshold.
The transmembrane potential is generated by
diffusion of ions down a concentration gradient.
The capability of a nerve terminal to rapidly and dramatically produce very large changes in calcium levels is most dependent on the
enormous gradient of calcium across the membrane.
The set of neurons and small ganglia associated with the digestive tract is called the _______ nervous system.
enteric
The different electrical signals occurring in nerve cells are caused by _______ the cell membrane.
fluxes of ions across
SNARE proteins participate in vesicle exocytosis by
forming a protein complex that pulls the vesicle membrane against the plasma membrane.
Gap junctions (electrical synapses)
have larger pores than voltage-gated ion channels
The TRP ion channel family includes channels responsive to
heat and cold
In their studies of the resting membrane potential of the squid giant axon, Hodgkin and Katz found that
increasing potassium outside the axon depolarized the axon's potential.
The two main families of neurotransmitter receptors are _______ and _______.
ionotropic; metabotropic
The synaptic potential
makes communication between nerve cells possible
Individual ion channels
may pass thousands of ions per millisecond.
The type of nerve cell that synapses upon muscles is called a(n)
motor neuron (or motoneuron)
Action potentials are generated
only when the cell reaches threshold
The _______ most directly affects the rate of information processing within the central nervous system.
propagation speed of action potentials
The calcium ATPase
pumps calcium in a cyclical process that utilizes energy from ATP.
A neuron that innervates (i.e., makes synaptic contact with) a large number of other neurons
represents divergent neural signaling
The mode of action potential propagation along myelinated axons is called
salutatory
A surprising result that emerged from the molecular analysis of ion channels was the
sheer number of different ion channels
Compared with normals, the decrease in quantal size observed in familial infantile myasthenia would be most consistent with
smaller synaptic vesicles
The protein that is thought to cross-link vesicles to actin to form a reserve vesicle pool is called
synapsin
The technique that first revealed the tremendous diversity of neuronal cell types (numbering in the hundreds or thousands in vertebrate animals) is called
the Golgi stain.
When current is injected into an axon,
the current will decay exponentially with increasing distance from the injection site (if no action potential is present). the current will propagate as an oscillating wave independently of its polarity.
In an experiment using a series of voltage steps to study the two different ionic currents associated with the action potential (as shown in Figure 3.2), it was found that
the early current increased initially, but then it decreased in size as the voltage step was increased.
The resting membrane potential is not exactly equal to the Nernst potential for potassium because
the membrane has some resting permeability to species other than potassium
Hodgkin and Katz proposed that sodium was the predominant ion associated with the firing of an action potential because
the membrane potential approaches the Na+ Nernst potential during the rising phase
In familial hemiplegic migraine, the underlying mutation in a calcium channel causes
the syndrome by some unknown mechanism.
Antibody staining is used to
visualize the distribution of specific proteins in the nervous system.
The most important factor determining whether a receptor-operated ion channel is inhibitory or excitatory is
whether the permeant ion's reversal potential is positive or negative to threshold
A measured membrane potential of +58 mV would be consistent with _______ inside the cell and _______ outside the cell.
10 mM Na+, 100 mM Na+
Which of the following was not seen in the voltage-clamp study of squid action potentials?
A sustained outward current as a result of hyperpolarization
Which of the following is a common, defining feature of membrane-bound active ion transporters?
All are able to move at least one ion against its concentration gradient.
Which of the following is an accepted criterion for defining a molecule to be a neurotransmitter?
All of the above It must be present in the presynaptic terminal. It must be released in response to presynaptic electrical activity. It must exert an effect on the postsynaptic cell.
Which of the following experiments would indicate a role for calcium in transmitter secretion?
All of the above 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 buffer into the presynaptic terminal
Which of the following appears to contribute to the selectivity filter of the potassium channel?
All of the above The channel pore narrows to fit the size of a non-hydrated potassium ion. Cations such as cesium are too large to pass through the pore. Cations such as sodium are too small to be dehydrated at the pore filter.
Animal toxins have been discovered that
All of the above block sodium channels. prolong the open state of sodium channels. alter the voltage-dependence of sodium channels. block potassium channels.
Cognitive neuroscience is concerned with
All of the above mathematical ability. emotions. language. abstract thought.
In the operation of sodium-potassium ATPase,
All of the above there is an obligatory coupling of sodium efflux and potassium influx. this transporter (or "pump") is electrogenic. phosphorylation and dephosphorylation are respectively associated with the sodium and potassium transport steps. the pump transports two potassium ions for every three sodium ions.
Which of the following is not a type of ion transporter that has been observed?
All of the above transporters have been observed. The sodium/calcium exchanger The sodium/potassium/chloride co-transporter The sodium/neurotransmitter co-transporter The sodium/proton exchanger
Which of the following does not stem from the application of Ohm's law to ionic conductances?
All permeant ions experience an identical driving force at each time point during the course of an action potential.
Which of the following is not integral to the action potential waveform?
An initial decrease in the potassium current
Which of the following factors is important in determining the membrane potential when there are multiple permeant ions?
Both a and b The concentration gradient of the individual ionic species The permeability of the membrane to the individual ionic species
Which of the following statements about neural and glial cells is false?
Both b and d The endoplasmic reticulum is concentrated in axons. Glial cells rapidly transmit long-range electrical signals.
Which of the following is not a cause of sensory receptor potentials?
Brain waves
The brain imaging technique that makes use of a narrow X-ray beam is called
CT
In tracking recycling of synaptic vesicles, using HRP as a vesicle marker, the observed sequence of movements of HRP was
Coated vesicle, endosome, vesicle reserve pool
Which of the following was not observed in studies measuring the efflux of radioactive sodium from the squid giant axon?
Dramatic increase of efflux during a brief train of action potentials
Which of the following is a feature that distinguishes the four model organisms from other animals that have been intensively studied by neuroscientists?
Ease of genetic analysis and manipulation
Which technique first produced unequivocal support for the neuron doctrine of the nervous system (as opposed to the reticular theory)?
Electron microscopy of nervous tissue
Which of the following statements about electrochemical equilibrium is false?
For a given ion concentration gradient, the resulting potential is independent of the number of charges on the ion
Which of the following is not a reason for the usefulness of the squid giant axon in neuronal studies?
Giant ion channels allow for the insertion of recording electrodes into the channels.
The equation used to calculate membrane potential when there are multiple permeant ions is called the _______ equation.
Goldman
Which of the following best describes nerve cells?
In comparison to copper wires, nerve cells are relatively poor conductors of electricity
Which of the following statements about the ionic permeability of cell membranes is false?
In resting nerve cells, the membrane is quite permeable to sodium.
Which of the following is not an established role for glial cells?
Integrating information to assist neural computation
Which of the following is not a variant of the patch clamp technique?
Intracellular
Which of the following is a major advantage to researchers of the Xenopus oocyte expression system?
It facilitates physiological characterization of modified ion channel genes.
Which of the following is not a true statement about a center-surround receptive field?
It is found only in primary sensory cortex.
Which of the following statements about multiple sclerosis (MS) is false?
It was recently proven that all cases of MS are due to persistent infection by a tropical parasite.
The inventor of voltage clamp was
Kenneth Cole.
The structural brain imaging technique that relies on atoms behaving as small magnets is called
MRI
Which of the following statements about the expression of genes in the nervous system is true?
Most of the genes in the human genome are expressed in the CNS.
Which of the following statements about myelination is false?
Myelin serves to sharply increase the time constant of the axon.
In which of the following ways do potassium channels in the squid giant axon differ from sodium channels?
Once the potassium channels open in response to a voltage step command, they tend to remain open
Which of the following is not a usual kind of potential exhibited by nerve cells?
Reaction
Which of the following was shown to eliminate the early inward current in squid giant axons?
Removal of external sodium
The scientist who shared the Nobel Prize with Camillo Golgi for his anatomical studies of the CNS was
Santiago Ramón y Cajal
Which of the following type of glial cell myelinates peripheral axons?
Schwann cells
Which of the following is not necessary for neurons to communicate electrically?
Separation of large amounts of electrical charge, with excess positive charges stored inside the cell