Neural Circuits & Behavior Quizzes

The resting membrane potential typically ranges from _______ to _______.

-40 mV; -90 mV

40 mV; 90 mV

0 mV; 90 mV

-90 mV; 90 mV

40 V; 90 V

-40 mV; -90 mV

Which of the following statements about action potentials is false?

They can transmit signals over long distances

They occur at threshold

They boost the spatial spread of electrical signals

They are elicited by hyperpolarization

They are all-or-none

They are elicited by hyperpolarization

The transmembrane potential is generated by

All of the above

high concentrations of specific leak channels

diffusion of ions down a concentration gradient

the selectivity of the membrane

ATP dependent pumps removing ions

All the above

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

The direction of the ion gradient determines the polarity of the membrane potential

Ionic gradients are necessary for the generation of the membrane potential

The size of the potential is proportional to the size of the ion gradient

Electrochemical equilibrium involves the movement of a relatively small number of ions

For a given ion concentration gradient, the resulting potential is independent of the number of charges on the ion

How will a neuron respond to an injection of negative current?

It will generate a single action potential

It will reach the threshold potential

It will generate multiple action potentials

It will have a positive electrical response

It will become hyperpolarized

It will become hyperpolarized

An action potential occurs if current injected into a neuron that _______ the neuron to reach _______ potential.

depolarizes; threshold

hyperpolarizes; synaptic

depolarizes; synaptic

hyperpolarizes; resting

hyperpolarizes; threshold

depolarizes; threshold

In a two-compartment model of a cell with a K+ permeable membrane, at K+ equilibrium potential, there is _______ flux of K+ ions

a large outward

a small outward

a small inward

no net

a large inward

no net

Typically, neurons firing action potentials encode a signal intensity by

sending signals of different sizes down different axonal branches

All of the above

firing at precise moments so as to signal different sized signals

changing the size of their action potentials.

changing the frequency of their action potentials

changing the frequency of their action potentials

The figure shows an electron micrograph of a chemical synapse in the cerebral cortex. Which statement about this synapse is accurate?

1. None of the above

2. A gap junction connects the two neurons via connexons that span the pre- and postsynaptic membranes.

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

4. Inside the postsynaptic neuron are synaptic vesicles, which fuse with the membrane in the postsynaptic density.

5. Inside the presynaptic neuron are synaptic vesicles, which fuse with the membrane in the postsynaptic density

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

What is the action of the neurotransmitter at a chemical synapse?

1. It transfers an action potential from the presynaptic neuron to the postsynaptic neuron.

2. It acts on receptors in the postsynaptic membrane.

3. It electrically activates the presynaptic neuron.

4. It depolarizes the postsynaptic membrane by delivering an electrical charge.

5. It crosses the postsynaptic membrane and then activates ion channels in the postsynaptic neuron.

It acts on receptors in the postsynaptic membrane.

In the sequence of events in neurotransmission, which event occurs just after the action potential arrives at the presynaptic terminal?

1. Fusion of the synaptic vesicles with the presynaptic membrane

2. Release of the neurotransmitter

3. Influx of Ca2+ into the presynaptic terminal

4. Packaging of the neurotransmitter

5. Delivery of the neurotransmitter to the presynaptic terminal

Influx of Ca2+ into the presynaptic terminal

Which event is the first in the series of events that take place during chemical synaptic transmission?

1. Synaptic vesicles fuse with the presynaptic membrane.

2. Voltage-gated Ca2+ channels open.

3. Neurotransmitter is released into the synaptic cleft.

4. Neurotransmitter binds to its receptors.

5. Influx of Ca2+ in the presynaptic terminal.

Voltage-gated Ca2+ channels open.

Which substances diffuse through connexon channels between pre- and postsynaptic neurons?

1. Small proteins

2. All of the above

3. Ions

4. Second messengers

5. ATP

All the above

The synaptic potential

1. All of the above

2. makes communication between nerve cells possible

3. propagates along axons

4. occurs only in response to external stimuli

5. determines the cells resting potential

makes communication between nerve cells possible

mall-molecule neurotransmitters are _______ for _______.

1. taken back into the presynaptic terminal; degradation

2. taken up by the postsynaptic cell; reuse

3. taken back into the presynaptic terminal; reuse

4. scattered in the synaptic cleft; reuse

5. taken up by the postsynaptic cell; degradation

taken back into the presynaptic terminal; reuse

Which structure can be found exclusively at an electrical synapse?

1. Synaptic vesicle

2. Neurotransmitter receptor

3. Presynaptic membrane

4. Connexon

5. Synaptic cleft

Connexon

Presynaptic and postsynaptic neurons that form _______ synapses are connected via _______.

1. chemical; connexons

2. electrical; the synaptic cleft

3. electrical; synaptic vesicles

4. electrical; gap junctions

5. chemical; neurotransmitter release

electrical; gap junctions

At which point during signal transmission at a chemical synapse is exocytosis occurring?

1. While Ca2+ enters the presynaptic terminal

2. During reuptake, as synaptic vesicles are reformed from the plasma membrane

3. During neurotransmitter release into the synaptic cleft

4. As neurotransmitter binds to its receptors

5. As voltage-gated Ca2+ channels are opening

How would application of a Ca2+ channel blocker affect the function of a synapse?

1. It would eliminate the postsynaptic potential but have no effect on presynaptic neuron.

2. It would increase the magnitude of postsynaptic potential.

3. It would eliminate the presynaptic Ca2+ current but have no effect on the postsynaptic potential.

4. It would decrease the magnitude of postsynaptic potential.

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

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