Question 1

Which of the following is the strongest analogy to explain the relationship between receptors and neurotransmitters?
A) Needle and thread
B) Bat and ball
C) Lock and key
D) Boat and sail

Accepted Answer

The relationship between receptors and neurotransmitters is often compared to a lock and key. Neurotransmitters are the keys that fit into the lock-like receptors on the surface of nerve cells. When the neurotransmitter "key" fits into the receptor "lock," it triggers a reaction in the nerve cell, such as the transmission of a signal to another nerve cell or the release of a hormone. This analogy accurately represents the specificity and selectivity of the interaction between neurotransmitters and receptors, as only certain neurotransmitters can bind to specific receptors, just as only certain keys can fit into specific locks.

Question 2

Neuronal communication is a two-step process. In the second step, which takes place between two neurons, what does the arrival of an action potential at the axon terminal of the first neuron signal?
A) The synthesis of neurotransmitters by specialized enzymes
B) The uptake of neurotransmitters from the extracellular space
C) The enzymatic breakdown of residual neurotransmitters
D) The release of neurotransmitters into the extracellular fluid

Accepted Answer

The arrival of an action potential at the axon terminal of the first neuron signals the release of neurotransmitters into the extracellular fluid, which is the second step of neuronal communication between two neurons.

Question 3

Which of the following statements is accurate regarding the generation of an action potential?
A) If a neuron becomes hyperpolarized to the threshold level, an action potential is inevitable.
B) Small hyperpolarizations lead to small action potentials, and large hyperpolarizations lead to large action potentials.
C) If a neuron becomes depolarized to the threshold level, an action potential is inevitable.
D) Small depolarizations lead to small action potentials, and large depolarizations lead to large action potentials.

Accepted Answer

Action potentials operate on an all-or-none principle, meaning if a neuron becomes depolarized to the threshold level, an action potential is triggered. The size of the action potential is not affected by the size of the depolarization once the threshold is reached.

Question 4

Marcus, who works in the laboratory of Dr. Flores, a prominent electrophysiologist, takes readings with a recording electrode placed within a squid axon. He reports to Dr. Flores that the cell is firing an action potential. What measurement did Marcus take with the recording electrode?
A) −70 mV
B) 0 mV
C) +40 mV
D) +70 mV

Accepted Answer

A recording electrode placed within a squid axon can pick up the electrical activity generated by the axon during an action potential. The resting membrane potential of a squid axon is around -70 mV, meaning it is negatively charged inside compared to outside. During an action potential, the membrane potential rapidly depolarizes to around +40 mV before repolarizing back to its resting potential. Therefore, Marcus would have measured a positive voltage of around +40 mV with the recording electrode, indicating that the axon had fired an action potential. Choice C (+40 mV) is the best choice.

Question 5

Synaptic communication between two neurons usually occurs via
A) direct contact.
B) molecular transduction.
C) chemical messengers.
D) electrical signaling.

Accepted Answer

Synaptic communication between two neurons typically involves the release of chemical messengers, known as neurotransmitters, from the presynaptic neuron. These neurotransmitters bind to receptors on the postsynaptic neuron, which initiate a series of events that can either excite or inhibit the postsynaptic neuron's activity. This process allows for precise control over the flow of information between neurons.

Question 6

Marcus works in the laboratory of Dr. Flores, an expert in the electrophysiology of squid axons. After taking a reading from a recording electrode placed within a squid axon, Marcus comments to Dr. Flores that the squid axon is at its resting potential. What measurement did Marcus take with the recording electrode?
A) −70 mV
B) −40 mV
C) 0 mV
D) +40 mV

Accepted Answer

The resting potential of a squid axon is typically around −70 mV. Marcus must have taken a voltage reading of −70 mV, indicating that the axon was not actively firing at that moment.

Question 7

How do drugs classified as SSRIs, such as Prozac, alter neuronal communication?
A) They increase the effectiveness of the neurotransmitter serotonin by stopping its diffusion from the synaptic cleft.
B) They decrease the effectiveness of the neurotransmitter serotonin by returning it to the axon terminal for recycling.
C) They increase the effectiveness of the neurotransmitter serotonin by blocking its reuptake into the axon terminal.
D) They decrease the effectiveness of the neurotransmitter serotonin by facilitating its metabolism by neuronal enzymes.

Accepted Answer

SSRIs, such as Prozac, work by blocking the reuptake of the neurotransmitter serotonin into the axon terminal, leading to an increase in serotonin concentration in the synaptic cleft. This enhances the effectiveness of serotonin in stimulating postsynaptic receptors, leading to changes in neuronal communication.

Question 8

Synaptic vesicles have been released from their protein anchors. What happens next?
A) The vesicles cross the synaptic gap, deliver their contents to the receptors, and dissolve into the fluid.
B) The vesicles migrate to the cell membrane, spill their contents into the synaptic gap, and complete their life cycle.
C) The vesicles cross the synaptic gap, enter the receiving neuron, and deliver their contents to the receptors.
D) The vesicles migrate to the cell membrane, spill their contents into the synaptic gap, and are refilled for later use.

Accepted Answer

The answer of Synaptic vesicles have been released from their...

Question 9

A squid axon is large enough to be visible to the naked eye, while a human axon can only be viewed with a microscope. Compared with an action potential for a human axon, the size of an action potential for a squid axon will be
A) the same.
B) smaller.
C) larger.
D) smaller or larger depending on the length of the axon.

Accepted Answer

The size (amplitude) of an action potential is consistent across different types of neurons, including those of humans and squids, due to the all-or-none principle governing action potentials.

Question 10

Marcus is excited to be working in the laboratory of Dr. Flores, an expert on electrical signaling in neurons. However, he is surprised to learn that the research is done on squid axons placed in sea water. He asks Dr. Flores the reasons for this approach. All of the following reasons are among those that Dr. Flores provides EXCEPT
A) that a recording electrode can be inserted into a squid axon without disrupting its function.
B) that the readings from inside the axon can be compared to the readings from the surrounding seawater.
C) that squid axons are myelinated, increasing the speed of propagation of an action potential.
D) that squid axons can be as great as 1 millimeter in diameter and are visible to the naked eye.

Accepted Answer

Squid axons are not myelinated; they are large in diameter, which helps in the rapid conduction of action potentials, but they do not have myelin sheaths like some vertebrate axons do. Myelination is a characteristic of certain vertebrate neurons that increases the speed of action potentials by insulating the axon and facilitating saltatory conduction. The large diameter of squid axons, rather than myelination, is what allows for their efficient signal transmission.

Question 11

Once the "threshold" for an action potential is reached what is the sequence of events that occur? 1. Potassium channels are activated, and potassium ions move out of the neuron.
2) Sodium channels are activated, and sodium ions move into the neuron.
3) The interior of the neuron becomes more negatively charged than the exterior.
4) The interior of the neuron becomes more positively charged than the exterior.
A) 1, 3, 4, 2
B) 2, 4, 1, 3
C) 4, 1, 2, 3
D) 3, 2, 1, 4

Accepted Answer

Once the "threshold" for an action potential is reached, sodium channels are activated, allowing sodium ions to move into the neuron, which causes the interior of the neuron to become more positively charged than the exterior (step 2 and 4). This depolarization then triggers the activation of potassium channels, allowing potassium ions to move out of the neuron, which causes the interior of the neuron to become more negatively charged than the exterior (step 1 and 3). Therefore, the correct sequence of events is 2, 4, 1, 3.

Question 12

Denise, a first-year graduate student, is getting ready to begin a lab rotation with Dr. Hudson, an expert on the nodes of Ranvier. What should Denise know about the nodes of Ranvier before beginning her lab rotation?
A) Action potentials occur only at the nodes of Ranvier in unmyelinated axons.
B) Action potentials occur only at the nodes of Ranvier in myelinated axons.
C) Action potentials "skip" over the nodes of Ranvier in unmyelinated axons.
D) Action potentials "skip" over the nodes of Ranvier in myelinated axons.

Accepted Answer

Action potentials occur only at the nodes of Ranvier in myelinated axons, allowing for saltatory conduction, which speeds up the transmission of electrical signals along the axon.

Question 13

Dr. Pohler is a neurobiologist studying ways to enhance the perception of sound in people with hearing difficulties. He discovers a natural neurotransmitter that increases the chance a neuron will fire an action potential, increasing sensitivity to sound. What is the effect of this neurotransmitter on the receiving neuron?
A) Inhibitory, causing hyperpolarization
B) Inhibitory, causing depolarization
C) Excitatory, causing hyperpolarization
D) Excitatory, causing depolarization

Accepted Answer

The neurotransmitter discovered by Dr. Pohler increases the chance a neuron will fire an action potential, which means it will excite the neuron and cause depolarization, making it more likely to transmit a signal to downstream neurons. Therefore, the effect of this neurotransmitter on the receiving neuron is excitatory, causing depolarization.

Question 14

Professor Freeman calls on his student Maya to describe how the presence of myelin affects an action potential. Maya should respond with which of the following statements?
A) Current flows along the unmyelinated segments and action potentials propagate along the myelinated portions of the axon, decreasing the speed and efficiency of the action potential.
B) Current flows under the myelin and action potentials propagate along the unmyelinated segments of the axon, decreasing the speed and efficiency of the action potential.
C) Current flows along the unmyelinated segments and action potentials propagate along the myelinated portions of the axon, increasing the speed and efficiency of the action potential.
D) Current flows under the myelin and action potentials propagate along the unmyelinated segments of the axon, increasing the speed and efficiency of the action potential.

Accepted Answer

Myelin sheaths insulate axons, allowing current to flow more efficiently under the myelin. Action potentials "jump" between the gaps in the myelin sheath (nodes of Ranvier), which are unmyelinated, speeding up signal transmission. This process is known as saltatory conduction.

Question 15

Following a spinal cord injury, formation of scar tissue prevents neuronal regeneration in the
A) central nervous system.
B) peripheral nervous system.
C) neurotransmitters.
D) intracellular fluid.

Accepted Answer

Scar tissue formation following a spinal cord injury primarily prevents neuronal regeneration in the central nervous system (CNS), not in the peripheral nervous system (PNS). The CNS includes the brain and spinal cord, where regenerative capabilities are limited, partly due to the inhibitory environment created by scar tissue.

Question 16

Chemical messengers used in neuronal communication are referred to as
A) neuroregulators.
B) neuromolecules.
C) neuromodulators.
D) neurotransmitters.

Accepted Answer

Chemical messengers used in neuronal communication are specifically called neurotransmitters. The other options are similar in meaning, but not as accurate or commonly used in scientific literature.

Question 17

The arrival of a(n)_____ causes synaptic vesicles to be released from their protein anchors, allowing the vesicles to fuse with the cell membrane and release _____ into the synaptic cleft.
A) action potential; neurotransmitters
B) neurotransmitter; an electrical charge
C) action potential; an electrical charge
D) neurotransmitter; more neurotransmitters

Accepted Answer

An action potential is an electrical signal that causes synaptic vesicles to release neurotransmitters into the synaptic cleft. This is the process of neurotransmission, which takes place at the synapse between two neurons. Choice B is incorrect because neurotransmitters themselves do not cause an electrical charge, but rather they transmit signals from one neuron to another. Choice C is partially correct, as an action potential does involve an electrical charge, but it is the release of neurotransmitters that actually transmits the signal across the synapse. Choice D is incorrect as it suggests that releasing more neurotransmitters somehow facilitates the transmission of signals, which is not necessarily true.

Question 18

Elaine, a graduate student in a neuroscience department, is interested in understanding the effects of popular herbal remedies on neuronal communication. After growing neurons in a petri dish, she exposes the neurons to several common herbal supplements. After performing a series of electrophysiology experiments, she notes that one class of herbal supplements caused the neurons to become depolarized. What does this result mean?
A) The difference between the electrical charges of the extracellular and intracellular recordings decreased, increasing the chances of an action potential.
B) The difference between the electrical charges of the extracellular and intracellular recordings decreased, decreasing the chances of an action potential.
C) The difference between the electrical charges of the extracellular and intracellular recordings increased, increasing the chances of an action potential.
D) The difference between the electrical charges of the extracellular and intracellular recordings increased, decreasing the chances of an action potential.

Accepted Answer

Depolarization refers to the reduction in the difference between the inside and outside electrical charges of a neuron, making the inside less negative compared to the outside. This process brings the neuron closer to the threshold needed to trigger an action potential, thereby increasing the likelihood of neuronal firing.

Question 19

Juan, a graduate student in an electrophysiology lab, stimulates an isolated neuron grown in a petri dish and measures its action potential. How will the neuron respond to the firing of the action potential?
A) Its dendrites will retract.
B) Its dendrites will extend.
C) It will take up chemical messengers.
D) It will release chemical messengers.

Accepted Answer

When a neuron fires an action potential, it typically results in the release of chemical messengers, known as neurotransmitters, from its axon terminals. These neurotransmitters then communicate with other neurons or cells by binding to their receptors.

Question 20

Marcus is conducting a squid axon electrophysiology experiment with Dr. Flores. While monitoring a recording electrode placed within a squid axon, Marcus reports to Dr. Flores that the neuron is in a refractory period. What does this mean?
A) The cell is hyperpolarized, and another action potential is unlikely or impossible.
B) The cell is depolarized and cannot fire another action potential.
C) The cell is hyperpolarized and is getting ready to fire a larger action potential.
D) The cell is depolarized and is getting ready to fire a larger action potential.

Accepted Answer

During the refractory period, the neuron is hyperpolarized and unable to fire another action potential until it returns to its resting membrane potential. Therefore, choice A is the correct answer as it describes the hyperpolarization and decreased likelihood of firing another action potential.

Quiz 4: The Biological Mind the Physical Basis of Behavior

Which of the following is the strongest analogy to explain the relationship between receptors and neurotransmitters?

Neuronal communication is a two-step process. In the second step, which takes place between two neurons, what does the arrival of an action potential at the axon terminal of the first neuron signal?

Which of the following statements is accurate regarding the generation of an action potential?

Marcus, who works in the laboratory of Dr. Flores, a prominent electrophysiologist, takes readings with a recording electrode placed within a squid axon. He reports to Dr. Flores that the cell is firing an action potential. What measurement did Marcus take with the recording electrode?

Synaptic communication between two neurons usually occurs via

How do drugs classified as SSRIs, such as Prozac, alter neuronal communication?

Synaptic vesicles have been released from their protein anchors. What happens next?

A squid axon is large enough to be visible to the naked eye, while a human axon can only be viewed with a microscope. Compared with an action potential for a human axon, the size of an action potential for a squid axon will be

Denise, a first-year graduate student, is getting ready to begin a lab rotation with Dr. Hudson, an expert on the nodes of Ranvier. What should Denise know about the nodes of Ranvier before beginning her lab rotation?

Professor Freeman calls on his student Maya to describe how the presence of myelin affects an action potential. Maya should respond with which of the following statements?

Following a spinal cord injury, formation of scar tissue prevents neuronal regeneration in the

Chemical messengers used in neuronal communication are referred to as

The arrival of a(n) _ causes synaptic vesicles to be released from their protein anchors, allowing the vesicles to fuse with the cell membrane and release _ into the synaptic cleft.

Juan, a graduate student in an electrophysiology lab, stimulates an isolated neuron grown in a petri dish and measures its action potential. How will the neuron respond to the firing of the action potential?

Marcus is conducting a squid axon electrophysiology experiment with Dr. Flores. While monitoring a recording electrode placed within a squid axon, Marcus reports to Dr. Flores that the neuron is in a refractory period. What does this mean?