1403 - Week 9 Homework Assignment

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1

In temporal summation, a single presynaptic neuron stimulates the creation of action potentials in a postsynaptic neuron when it

------

stops firing long enough to allow the postsynaptic neuron to recover.

runs out of neurotransmitter.

fires at a steady rate that allows the postsynaptic neuron to return to resting potential.

recruits other presynaptic neurons to begin to fire.

fires at a fast enough rate that the sum of EPSPs in the postsynaptic neuron moves above threshold.

fires at a fast enough rate that the sum of EPSPs in the postsynaptic neuron moves above threshold.

2

EPSPs are caused by a hyperpolarization of the post-synaptic membrane.

--

True

False

False

3

During repolarization, more sodium ions are brought into the cell to reset the membrane potential.

--

True

False

False

4

The generation of an action potential is an electrochemical event. This electrical event occurs:

------

within the neuron

only in nerves with neurolemma

within the myelin sheath

in microglia

within the neuron

5

Graded potentials:

----

arise when ion movement causes a minor change in the resting membrane potential.

usually propagate down the length of an axon.

occur when voltage-gated channels open.

are most often observed in axons.

are usually associated with ion movement through leakage channels.

arise when ion movement causes a minor change in the resting membrane potential.

6

Consider the cell body of a neuron. Through which types of ion channel might sodium enter the cell body? Check all that apply!

-------

Na+1/K+1 ATPase

ligand-gated channels

voltage gated channels

leakage channels

leakage channels

7

Which of the following ions pass through the resting neuronal cell membrane most easily?

--

sodium

calcium

potassium

phosphate

potassium

8
card image

When summation results from buildup of neurotransmitter released simultaneously by several presynaptic end bulbs, it is called

Temporal summation

Wallerian degeneration

Saltatory conduction

Spatial summation

Spatial summation

9

In temporal summation, a single presynaptic neuron stimulates the creation of action potentials in a postsynaptic neuron when it

------

stops firing long enough to allow the postsynaptic neuron to recover.

runs out of neurotransmitter.

fires at a steady rate that allows the postsynaptic neuron to return to resting potential.

recruits other presynaptic neurons to begin to fire.

fires at a fast enough rate that the sum of EPSPs in the postsynaptic neuron moves above threshold.

fires at a fast enough rate that the sum of EPSPs in the postsynaptic neuron moves above threshold.

10

EPSPs are caused by a hyperpolarization of the post-synaptic membrane.

----

True

False

False

11

During repolarization, more sodium ions are brought into the cell to reset the membrane potential.

-----

True

False

False

12

The generation of an action potential is an electrochemical event. This electrical event occurs:

-----

within the neuron

only in nerves with neurolemma

within the myelin sheath

in microglia

within the neuron

13

Graded potentials:

-----

arise when ion movement causes a minor change in the resting membrane potential.

usually propagate down the length of an axon.

occur when voltage-gated channels open.

are most often observed in axons.

are usually associated with ion movement through leakage channels.

arise when ion movement causes a minor change in the resting membrane potential.

14

Consider the cell body of a neuron. Through which types of ion channel might sodium enter the cell body? Check all that apply!

-----

Na+1/K+1 ATPase

ligand-gated channels

voltage gated channels

leakage channels

leakage channels

15

Which of the following ions pass through the resting neuronal cell membrane most easily?

------

sodium

calcium

potassium

phosphate

calcium

16

A resting nerve fiber is polarized because the concentration of

-----

Na+ and K+ ions is higher on the inside of the cell membrane

Na+ and K+ ions is higher outside the cell membrane

Na+ is higher on the inside and K+ is higher on the outside

Na+ is higher on the outside and K+ is higher on the inside

Na+ is higher on the outside and K+ is higher on the inside

17

A depolarizing graded potential

-----

makes the membrane less polarized.

is the last part of an action potential.

is considered a type of action potential.

is seen when the cell approaches threshold.

makes the membrane more polarized.

makes the membrane less polarized.

18

When a depolarizing graded potential makes the axon membrane depolarize to threshold,

-----

ligand-gated Ca+2 channels close rapidly.

voltage-gated Ca+2 channels open rapidly.

ligand-gated Na+ channels close rapidly.

voltage-gated Na+ channels open rapidly.

none of these choices occur.

voltage-gated Na+ channels open rapidly.

19

During this period, a second action potential can only be initiated by a larger than normal stimulus

----

Latent period

Absolute refractory period

Relative refractory period

All of these choices

None of these choices

Relative refractory period

20

Name the type of membrane channel that opens in response to changes in membrane potential and is located in axons of all types of neurons.

----

voltage-gated channels

leakage channel

temperature-sensitive channel

mechanically gated channels

ligand-gated channels

voltage-gated channels

21

To answer this question, first click here to view the associated animation.

In a graded potential, the voltage does not diminish with the distance.

----

True

False

False

22

To answer this question, first click here to view the associated animation.

The resting potential is maintained by the presence of

----

many efflux K+ pores

the Na+/K+ pump

an ATP-driven pump moving K+ into the cell

all of these

all of these

23

To answer this question, first click here to view the associated animation.

The larger the diameter of an axon, the faster the conduction of an action potential.

----

True

False

True

24

To answer this question, first click here to view the associated animation.

Myelinated axons are capable of salutatory conduction. This allows for more rapid action potential conduction because

-----

repolarization occurs across the entire membrane.

repolarization occurs only at the Nodes of Ranvier.

depolarization occurs only at the Nodes of Ranvier.

depolarization occurs across the entire membrane

depolarization occurs only at the Nodes of Ranvier.

25

To answer this question, first click here to view the associated animation.

Which situation will see the fastest conduction rate across an axon?

-----

unmyelinated axon in with a thin axon diameter

myelinated axon in with a wide axon diameter

unmyelinated axon

myelinated axon

myelinated axon in with a wide axon diameter

26

To answer this question, first click here to view the associated animation

Some voltage-gated channels do not allow ions to pass through when their activation gate is open because

-----

a competitive ion of another type passes through instead.

there is a second gate, an inactivation gate, that closes to block the channel.

their gate is temporarily surrounded by like charges which repel the ions that normally would pass through.

there is a malfunction that occurs in the channel that causes it to change shape and block ion passage.

there is a second gate, an inactivation gate, that closes to block the channel.

27

To answer this question, first click here to view the associated animation

When the threshold of voltage-gated channels is reached and voltage-gated channels open, the resulting change in membrane potential is known as a(n)

-----

transition state.

graded potential.

induction mode.

action potential.

action potential.

28

To answer this question, first click here to view the associated animation

If I can block neurotransmitters attaching to chemically-gated sodium channels, what will be the result?

----

The cell will depolarize but not repolarize

An action potential will not be produced

The cell will die

The cell will become hyperactive

An action potential will not be produced