Deck 11: Organization of the Brain Stem

Question 1

Which of the following factors influences the conduction velocity of the action potential through the axon?

A) Axon diameter
B) Myelin thickness
C) Ion channel density
D) All of the above

Answer 1

D

Question 2

In the normal axon, reverse propagation of the action potential is not possible because the membrane is

A) Refractory because of sodium channel inactivation
B) Refractory owing to potassium channel inactivation
C) Refractory as a result of sodium ion influx
D) Refractory because of potassium ion influx
E) At its resting potential

Answer 2

A

Question 3

A 31-year-old woman is diagnosed with depression and prescribed a selective serotonin reuptake inhibitor. Which of the following is a precursor of serotonin?

A) Lysine
B) Glutamine
C) Tryptophan
D) Histidine
E) Threonine

Answer 3

C

Question 4

Which of the following is considered the rate-limiting step in the synthesis of acetylcholine?

A) Transport of choline into the neuron
B) Acetylcholinesterase production
C) Choline acetyltransferase activity
D) Acetyl CoA availability

Question 5

The stimulus intensity required to initiate an action potential is referred to as which of the following?

A) Saturation
B) Threshold
C) Adaptation
D) Frequency coding
E) Refractory period

Question 6

Which of the following most accurately represents the order of events for transmission at a G-protein coupled receptor?

A) Activation of a G-protein, binding of the neurotransmitter, activation of the effector
B) Binding of the effector, binding of the neurotransmitter, activation of a G-protein
C) Binding of the neurotransmitter, activation of a G-protein, activation of the effector
D) Activation of the effector, binding of the neurotransmitter, activation of a G-protein
E) Binding of a G-protein, binding of the neurotransmitter, activation of the effector

Question 7

High concentrations of acetylcholine maintained at the neuromuscular junction for several seconds would result in which of the following?

A) Desensitization
B) Hyperexcitation
C) Inhibition
D) Saturation
E) Recruitment

Question 8

A research scientist is interested in the effects of various toxins on the action potential in nerve cells. During one of the electrophysiological tests, the scientist injects tetrodotoxin (TTX) into the bathing solution. Which aspect of the action potential will most likely be affected by the injection of TTX?

A) Depolarization due to K⁺ channel blockade
B) Depolarization due to Na⁺ channel blockade
C) Depolarization due to Na⁺ channel opening
D) Hyperpolarization due to K⁺ channel blockade
E) Hyperpolarization due to Na⁺ channel blockade

Question 9

The undershoot of the action potential is primarily attributable to which of the following?

A) Sodium influx
B) Sodium efflux
C) Potassium influx
D) Potassium efflux

Question 10

Connections to the globus pallidus from the putamen are an example of an inhibitory synapse in the central nervous system that utilizes which of the following neurotransmitters?

A) Glutamate
B) Gamma-aminobutyric acid
C) Diacylglycerol
D) Adenylyl cyclase
E) Enkephalin