PNB 2264: Quiz 6

Which of the following would typically increase

the size of a postsynaptic potential at a chemical synapse?

All of the Above

In chemical synaptic transmission involving a second messenger, the second messenger

is in the cytosol of the postsynaptic cell

Action potentials typically are initiated

At the axon hillock

Which happens last during an action potential?

closing of potassium (K+)

channels

The falling (downward) phase of a neuronal action potential is caused by opening of

potassium channels

Most of the ion channels that are open when a cell is at its resting membrane potential selectively allow which type of ion to pass through?

potassium (K+)

Which of the following contributes to the negative resting potential of a typical cell?

all of the above

If we could magically add open K+ (potassium) channels to the cell membrane of a typical neuron at rest, this would

hyperpolarize the neuron

Cells have a resting potential in part because of

all of the above

A drug that makes inactivation of sodium channels begin sooner would

decrease amplitudes of action potentials

When a neuron receives synaptic inputs at overlapping times from several other neurons, this is called

summation

Which of the following contributes to a typical resting potential?

All of the above

Which of the following normally contributes to cells having a negative resting potential?

sodium-potassium (Na+/K+) pumps

A particular type of positively charged ion (cation) is more concentrated outside a particular cell than inside the cell. The Nernst equilibrium potential for this ion is

above zero millivolts (positive)

During a neuronal action potential, there is a net flux out of the cell of which of the following?

potassium

Repolarization of a neuron during an action potential is caused in part by opening of

K+ (potassium) channels

Neuronal action potentials require

voltage-gated sodium (Na+) channels

Which of the following is typically required for chemical synaptic transmission only if it involves a second messenger?

G-proteins

The equilibrium potential for potassium (EK) is typically about

-90 mV

Which of the following normally contributes to cells having a negative resting potential?

sodium-potassium (Na+/K+) pumps

Which of the following is true of every voltage-gated ion channel?

all of the above

Neurons typically release neurotransmitter from their

axon terminals

Which of the following can act as a neurotransmitter?

all of the above

Which of the following typically has the lowest (most negative) equilibrium potential in your cells?

potassium

Which of the following ions typically has the largest role in creating a resting membrane potential?

K+ (potassium

Na+ (sodium) quickly flows into a neuron during the rising phase of an action potential due to

positive feedback

Which of the following is a reason that the membrane potential (Vm) stops rising during the depolarizing (rising) phase of an action potential?

all of the above

Which of the following is a reason that neurons have a refractory period?

sodium (Na+) channels inactivate

The resting membrane potential of a cell would be more negative than normal if

all sodium (Na+) channels were removed from the cell membrane

n artificial cell has a net positive charge due to impermeant cations (positively charged ions) inside it. In addition, the fluid inside and just outside the cell contains 1 M NaCl. The cell is initially impermeable to Na+ and Cl-. At a certain moment, it becomes permeable to Na+. The Na+ will then have a net movement

out of the cell

In a myelinated axon, Na+ (sodium) channels

are found mainly in nodes of Ranvier

Which of these happens last during an action potential?

closing of potassium (K+) channels

Which of the following has two kinds of voltage-dependent gates?

voltage-gated sodium (Na+) channels

If you could magically increase the extracellular concentration of calcium (Ca2+) surrounding the axon terminal at an excitatory chemical synapse, this would

increase the size of the excitatory postsynaptic potential (EPSP)

When a neuron receives synaptic inputs at overlapping times from several other neurons, this is called

summation

The calcium ion (Ca2+) concentration is doubled

in the interstitial fluid surrounding a certain chemical synapse which normally produces inhibitory postsynaptic potentials (IPSPs). This will cause future postsynaptic potentials at this synapse to

be abnormally large IPSPs

Cells have a resting potential in part because of

all of the above

If a cell changes its membrane potential from -70 mV to -50 mV, it has been

depolarized

The equilibrium potential for potassium (EK) is typically about

-90 mV

In myelinated axons, action potentials

only occur at nodes of Ranvier

Which of the following has two kinds of voltage-dependent gates?

voltage-gated sodium (Na+) channels

A drug that has the same effect as one of our body's own neurotransmitters is called

an agonist

Which of the following contributes to making a typical cell more negative on the inside than the outside?

all of the above

In myelinated axons,

all of the above

An action potential refractory period occurs partly because

sodium (Na+) channels are inactivate

At a chemical synapse, presynaptic exocytosis of neurotransmitter is caused by

influx of Ca2+

Which of the following is typically more concentrated inside a cell?

potassium (K+)

For a cell at a typical resting potential, which of the following types of ions typically would have a net movement against its electrical gradient (assuming the membrane is permeable to this ion)?

potassium (K+)

Gap junctions are required for

electrical synaptic transmission

A drug that prevents one of your nervous system's own neurotransmitters from activating its postsynaptic receptors is called

an antagonist

A molecule that attaches to a particular kind of ion channel and prevents the ion channel from opening is called

an antagonist

NASA's Spirit rover has just discovered life on Mars! In the alien organism's cells, the voltage inside is always positive compared to the voltage outside the cells. The inside and the outside of these cells both contain 1 M sodium ions (Na+). If the cell membranes become permeable to Na+, the net flux of Na+

will be

out of the cell

For a cell at a typical resting potential, which of the following types of ions typically would have a net movement against its electrical gradient (assuming the membrane is permeable to this ion)?

potassium (K+)

Which of the following happens first during an action potential?

voltage-gated sodium (Na+) channels open

Immediately after an action potential, a neuron typically cannot generate another action potential, due to

the inactivation of sodium (Na+) channels

The potassium (K+) channels involved in neuronal action potentials open in response to

depolarization

A neuron's resting potential is typically nearest the equilibrium potential for

potassium ions (K+)

As an action potential propagates along an axon from the axon hillock to the axon terminals, the action potential

stays the same size

An artificial cell has a net positive charge due to impermeant cations (positively charged ions) inside it. In addition, the fluid inside and just outside the cell contains 1 M NaCl. The cell is initially impermeable to Na+ and Cl-. At a certain moment, it becomes permeable to Na+. The Na+ will then have a net movement

out of the cell

As an action potential propagates along an axon from the axon hillock to the axon terminals, the action potential

stays the same size

Action potentials are propagated fastest along axons that are

large-diameter and myelinated

Which of the following happens latest at a chemical synapse involving a second messenger (i.e., metabotropic)

ligand-gated ion channels open

All chemical synaptic potentials require in the postsynaptic membrane

ligand-gated channels

For a cell at a typical resting potential, which of the following would depolarize the cell?

increasing the extracellular K+ concentration