Question 1

As a result of the way nerve impulses are propagated,they are unidirectional.Which of the following does not contribute to this phenomenon?
A)The time interval encompassed by the refractory period does not allow the impulse to travel in reverse.
B)Presynaptic neurotransmitters and postsynaptic receptors are separated.
C)Unidirectional sodium and potassium channels open only toward the axon of the nerve cell.
D)Sensory processes are oriented in such a manner that the information is targeted to the dendrites of the nerve cell.
E)none of the above

Accepted Answer

The opening of sodium and potassium channels is not inherently unidirectional; it is the refractory period and synaptic structure that ensure unidirectional propagation.

Question 2

The resting potential of a particular nerve cell is -66 mV.Depolarization of the membrane will shift the membrane potential toward
A)-90 mV.
B)-66 mV.
C)0 mV.
D)There will be no change.
E)There is not enough information to tell.

Accepted Answer

Depolarization of the membrane means the membrane potential becomes less negative (closer to 0 mV). Therefore, the membrane potential will be shifted towards 0 mV. None of the other options reflect depolarization.

Question 3

In the graph above,the point at which the potassium channels open is indicated by the letter
A)A.
B)B.
C)C.
D)D.
E)E.

Accepted Answer

Potassium channels typically open during the repolarization phase of an action potential, which is often indicated by a downward slope following the peak of the action potential on a graph.

Question 4

A particular neuron does not release neurotransmitters into the synaptic cleft.Further investigation shows that this cell does not respond to calcium ions that are necessary for t- and v-SNARE complex interaction.The most likely problem is associated with the function of
A)synaptic boutons.
B)acetylcholinesterase.
C)synaptotagmin.
D)GABA receptors.
E)calcium ions.

Accepted Answer

Synaptotagmin is a protein that acts as a calcium sensor and is essential for triggering neurotransmitter release by facilitating the interaction of t- and v-SNARE proteins in response to calcium ions.

Question 5

The parts of the graph indicated at points C,D,and E represent
A)depolarization.
B)hyperpolarization.
C)the refractory period.
D)repolarization.
E)sodium channel activity.

Accepted Answer

The parts of the graph indicated at points C, D, and E all represent repolarization. This is characterized by the return of the membrane potential to its resting state after depolarization. Choice A, depolarization, refers to the initial increase in membrane potential from its resting state, while choice B, hyperpolarization, refers to a decrease below the resting potential. The refractory period (choice C) is a period of time during which an excitable cell or tissue is incapable of responding to a stimulus. Sodium channel activity (choice E) is a component of the depolarization phase, in which sodium ions enter the cell to cause the initial change in membrane potential.

Question 6

Of all of the ions associated with generating the resting membrane potential,the permeability of the membrane to ________ is the most important.
A)sodium ions
B)potassium ions
C)chloride ions
D)all of the above
E)none of the above

Accepted Answer

The answer of Of all of the ions associated with...

Question 7

Based on the graph above,after approximately what period of time could another impulse be propagated?
A)1 msec
B)2 msec
C)3 msec
D)4 msec
E)immediately following the first stimulation

Accepted Answer

The answer of Based on the graph above,after approximately what...

Question 8

Refer to the graph above.At the same time that the stimulus was introduced,a drug that specifically inhibits sodium channels was added to the system.The effect this would have is that the membrane would
A)not depolarize.
B)depolarize for the first impulse but not for a second one.
C)not be able to repolarize.
D)repolarize, but would not for a second impulse.
E)none of the above

Accepted Answer

Sodium channels are responsible for depolarization of the membrane, so inhibiting these channels would prevent depolarization from occurring. Therefore, the membrane would not depolarize in response to the stimulus, regardless of whether it is the first or second impulse.

Question 9

The portion of the nervous system that is associated with the control of involuntary activities is the
A)central nervous system.
B)peripheral nervous system.
C)autonomic nervous system.
D)somatic nervous system.
E)automatic nervous system.

Accepted Answer

The autonomic nervous system is responsible for controlling involuntary activities such as heart rate, digestion, and respiratory rate. The central nervous system and peripheral nervous system both have components that can control these activities, but they are not solely responsible for them. The somatic nervous system is responsible for voluntary movements, while the term "automatic nervous system" is not correct terminology.

Question 10

The sweetener aspartame is a known excitotoxin.With regard to nerve cells,ingestion of this substance results in chronic nerve stimulation.With your knowledge of action potentials,this toxin must
A)stimulate continual impulses at the cell body.
B)stimulate continual impulses at the dendrite.
C)bind the nodes of Ranvier.
D)block the synaptic cleft.
E)stimulate continual impulses at the presynaptic receptors.

Accepted Answer

Excitotoxins like aspartame stimulate the continual impulses at the dendrite of nerve cells, leading to chronic nerve stimulation. This can eventually result in damage to the nerve cells and contribute to neurological disorders.

Question 11

Refer to the graph above.If the myelin fibers were stripped from this membrane,you would expect the action potential cycle to go
A)much faster than depicted in the graph.
B)much faster than normal but not peak at 30 mV.
C)slower than depicted in the graph.
D)much slower than normal but peak much higher than 30 mV.
E)none of the above

Accepted Answer

Myelin fibers act as insulation around the axon, which allows for saltatory conduction and thus speeds up the action potential cycle. Without myelin fibers, the action potential would have to propagate through the entire length of the axon, leading to a slower propagation speed compared to the depicted graph.

Question 12

Based on your knowledge of nerve transmission,this movement of ions will
A)stimulate a change in a postsynaptic membrane.
B)not stimulate a change in a postsynaptic membrane.
C)stimulate a change in a postsynaptic membrane if three channel events are combined.
D)stimulate a change in a postsynaptic membrane if 50 channel events are combined.
E)generate a current resulting in membrane depolarization.

Accepted Answer

The answer of Based on your knowledge of nerve transmission,this...

Question 13

Which of the following is a disease specifically caused by an autoimmune response against acetylcholine receptors?
A)Grave's disease
B)myasthenia gravis
C)systemic lupus erythematosus
D)Hashimoto's thyroiditis
E)celiac disease

Accepted Answer

Myasthenia Gravis is a disease that is specifically caused by an autoimmune response against acetylcholine receptors. This leads to muscle weakness and fatigue, especially in facial and neck muscles, and can also affect breathing and swallowing. The other options listed are autoimmune diseases, but they do not involve the same target of acetylcholine receptors.

Question 14

The axon branches of a typical neuron terminate at structures called
A)synapses.
B)boutons.
C)glia.
D)nodes of Ranvier.
E)myelin sheath.

Accepted Answer

The axon branches of a neuron terminate at structures called boutons, which are also known as axon terminals or terminal boutons. These structures are involved in transmitting signals to other neurons or effector cells.

Question 15

In the graph above,at what point in the action potential will the sodium channels be opened?
A)A
B)B
C)C
D)D
E)E

Accepted Answer

Sodium channels open at the beginning of the depolarization phase, which is typically represented by point A in an action potential graph.

Question 16

Which neurotransmitter is not an amino acid derivative?
A)GABA
B)serotonin
C)histamine
D)dopamine
E)acetylcholine

Accepted Answer

Acetylcholine is not an amino acid derivative; it is synthesized from choline and acetyl-CoA.

Question 17

Under times of great stress or shock,which of the following neurotransmitters interferes with the perception of pain?
A)endocannabinoids
B)GABA
C)catecholamines
D)enkaphalins
E)calcium ions

Accepted Answer

Enkaphalins are endogenous opioids that are released during times of stress or shock. They bind to opioid receptors in the brain and spinal cord, inhibiting the transmission of pain signals and reducing the perception of pain.

Question 18

Based on the graph above,the threshold voltage appears to be approximately
A)60 mV.
B)30 mV.
C)0 mV.
D)-30 mV.
E)-60 mV.

Accepted Answer

The answer of Based on the graph above,the threshold voltage...

Question 19

All of the following are glial cells except
A)interneurons.
B)oligodendrocytes.
C)astrocytes.
D)Schwann cells.
E)both choices A and D

Accepted Answer

Interneurons are not glial cells. They are a type of neuron that communicates with other neurons in the central nervous system. The other choices (B, C, and D) are all types of glial cells that support and protect neurons.

Question 20

An electrical current of 1 A is approximately 6 x 10¹⁸ electrical charges per second; how many ions pass through the channel when it is open?
A)144,000 ions
B)2400 ions
C)8,640,000 ions
D)8640 ions
E)You cannot determine this from the information given.

Accepted Answer

The answer of An electrical current of 1 A is...

Quiz 13: Signal Transduction Mechanisms: Ielectrical and Synaptic Signaling in Neurons

As a result of the way nerve impulses are propagated,they are unidirectional.Which of the following does not contribute to this phenomenon?

The resting potential of a particular nerve cell is -66 mV.Depolarization of the membrane will shift the membrane potential toward

In the graph above,the point at which the potassium channels open is indicated by the letter

A particular neuron does not release neurotransmitters into the synaptic cleft.Further investigation shows that this cell does not respond to calcium ions that are necessary for t- and v-SNARE complex interaction.The most likely problem is associated with the function of

The parts of the graph indicated at points C,D,and E represent

Of all of the ions associated with generating the resting membrane potential,the permeability of the membrane to ________ is the most important. A)sodium ions B)potassium ions C)chloride ions D)all of the above E)none of the above

Based on the graph above,after approximately what period of time could another impulse be propagated?

Refer to the graph above.At the same time that the stimulus was introduced,a drug that specifically inhibits sodium channels was added to the system.The effect this would have is that the membrane would

The portion of the nervous system that is associated with the control of involuntary activities is the

The sweetener aspartame is a known excitotoxin.With regard to nerve cells,ingestion of this substance results in chronic nerve stimulation.With your knowledge of action potentials,this toxin must

Refer to the graph above.If the myelin fibers were stripped from this membrane,you would expect the action potential cycle to go

Which of the following is a disease specifically caused by an autoimmune response against acetylcholine receptors?

The axon branches of a typical neuron terminate at structures called

In the graph above,at what point in the action potential will the sodium channels be opened?

Which neurotransmitter is not an amino acid derivative?

Under times of great stress or shock,which of the following neurotransmitters interferes with the perception of pain?

Based on the graph above,the threshold voltage appears to be approximately

All of the following are glial cells except

An electrical current of 1 A is approximately 6 x 10¹⁸ electrical charges per second; how many ions pass through the channel when it is open?