Deck 41: Neuroscience I: Cells of the Nervous System

Question 1

A neuron innervating your bicep muscle would be considered part of the

A) central nervous system.
B) peripheral nervous system.
C) autonomic nervous system.
D) sympathetic nervous system.
E) parasympathetic nervous system.

Answer 1

peripheral nervous system.

Question 2

Which part of the neuron is responsible for basic cellular maintenance functions?

A) axon
B) dendrite
C) soma
D) myelin sheath
E) axon hillock

Answer 2

soma

Question 3

Which part of the neuron is responsible for propagating action potentials?

A) axon
B) dendrite
C) soma
D) myelin sheath
E) nucleus

Answer 3

axon

Question 4

What proportion of the brain (approximately) is made up of neurons?

A) 100%
B) 70%
C) 50%
D) 20%
E) 2%

Question 5

Which of the following carry electrical signals AWAY from the CNS?

A) sensory neuron
B) motor neuron
C) interneuron
D) glial cell
E) All of these choices are correct

Question 6

Which of the following always connects neurons to other neurons?

A) sensory neuron
B) motor neuron
C) interneuron
D) glial cell
E) None of these choices are correct.

Question 7

The resting membrane potential (inside relative to outside) of the squid giant axon is approximately

A) -300 mV.
B) -70 mV.
C) 0 mV.
D) 70 mV.
E) 300 mV.

Question 8

Which ions are important for establishing the resting potential in neurons?

A) Na⁺
B) K⁺
C) Intracellular anions (e.g., proteins)
D) H⁺
E) All of the choices other than H⁺ are correct

Question 9

At rest, neurons exhibit a negative membrane potential. This is most DIRECTLY due to

A) movements of negatively charged proteins and nucleic acids across the membrane.
B) passive leakage of Na⁺ions across the membrane.
C) passive leakage of K⁺ions across the membrane.
D) movement of Na⁺ ions through voltage-gated Na+ channels.
E) movement of K⁺ ions through voltage-gated K+ channels.

Question 10

In a neuron at rest, which of the following is TRUE?

A) Leakage of sodium ions out of the neuron is greater than leakage of potassium ions into the neuron.
B) Leakage of sodium ions into the neuron is greater than leakage of potassium ions out of the neuron.
C) Leakage of potassium ions out of the neuron is greater than leakage of sodium ions into the neuron.
D) Leakage of potassium ions into the neuron is greater than leakage of sodium ions out of the neuron.

Question 11

During the rapid increase in membrane potential seen in the upsweep of the action potential, which of the following is TRUE?

A) Both the activation and inactivation gates of the voltage-gated sodium channels are open.
B) The voltage-gated potassium channel is open.
C) The potassium leak channels are closed.
D) The sodium leak channels are closed.
E) The sodium/potassium pump has reversed directions and is pumping sodium in and potassium out.

Question 12

Why is it critical that the K+ channel activation gate responds slightly more slowly to depolarization than the Na+ channel activation gate?

A) If they showed identical response times, movements of Na+ and K+ ions would cancel out each other's effects on membrane potential changes.
B) If they showed identical response times, movements of Na+ and K+ ions would magnify each other's effects on membrane potential changes, creating dangerously large action potentials.
C) It is not critical and there would be no change in action potential characteristics if this difference in response time did not exist.

Question 13

The key feature of the action potential that prevents it traveling backwards towards the soma as well as forwards down the axon is

A) the activation state of the voltage-gated Na⁺ channel.
B) the inactivation state of the voltage-gated Na⁺ channel.
C) the activation state of the voltage-gated K⁺ channel.
D) the inactivation state of the voltage-gated K⁺ channel.
E) the temporary cessation in activity of the Na⁺/K⁺ pump.

Question 14

All of the following statements about initiation and transmission of action potentials in neurons are correct EXCEPT:

A) The rate of transmission of an action potential is directly related to the diameter of the axon.
B) Information about the intensity of a stimulus is conveyed by changes in the size of the action potential generated.
C) The resting potential is maintained by differential ion permeabilities and the sodium-potassium pump.
D) Once initiated, local depolarizations stimulate a moving wave of depolarization down the axon.
E) A stimulus to the neuron can either depolarize or hyperpolarize the neuronal membrane.

Question 15

Synaptic integration refers to

A) the summing of multiple excitatory or inhibitory influences in a postsynaptic neuron.
B) the fusing of presynaptic and postsynaptic membranes.
C) the binding of Ca²⁺ions to secretory vesicles in presynaptic neurons.
D) the binding of secretory vesicles to the presynaptic neuron membrane.
E) the enzymatic degradation of neurotransmitters in the synaptic cleft.

Question 16

Rising intracellular levels of which ion are necessary for neurotransmitter release from a neuron?

A) K⁺
B) Cl^-
C) Mg²⁺
D) HCO₃^-
E) Ca²⁺

Question 17

Otto Loewi performed an experiment in which he electrically stimulated the vagus nerve connected to one frog heart and let the fluid bathing this first heart pass to a second chamber containing a second frog heart not connected to a nerve. What did Loewi observe?

A) There was no effect on the beating of either heart.
B) The first heart showed an increase in beat rate, but there was no change in the second heart.
C) The first heart showed an increase in beat rate and so did the second heart.
D) The first heart showed a decrease in beat rate, but there was no change in the second heart.
E) The first heart showed a decrease in beat rate and so did the second heart.

Question 18

The major class(es) of neurotransmitter receptor(s) found in postsynaptic membranes are

A) metabotropic and neurotropic.
B) ionotropic and gonadotropic.
C) gonadotropic and neurotropic.
D) neurotropic and isotopic.
E) metabotropic and ionotropic.

Question 19

You could observe saltatory conduction in a crayfish.