Question 1

In a resting neuron, there is a difference in electrical charge across the cell membrane because A) voltage-gated channels in the membrane allow Na⁺ to enter the cell. B) the concentration of Na⁺ is higher inside than outside the cell. C) ion transporters require energy and are not active in a resting neuron. D) K⁺ ions are pumped through channels until they reach equilibrium. E) leak channels allow K⁺ ions to diffuse out of the cell.

Accepted Answer

In a resting neuron, the difference in electrical charge across the cell membrane is due to the presence of leak channels. These channels allow K⁺ ions to slowly leak out of the cell, creating a net negative charge inside the cell compared to the outside. This creates a resting membrane potential, which is typically around -70mV in neurons. Options A, B, C, and D are incorrect because they do not accurately describe the underlying process that creates the resting membrane potential.

Question 2

Failure of the blood-brain barrier has been implicated in triggering seizures.Which cells might be involved in failure of the blood-brain barrier?
A) Neuroblasts
B) Oligodendrocytes
C) Microglia
D) Astrocytes
E) Schwann cells

Accepted Answer

Astrocytes are a type of glial cell in the brain and are critical in the formation and maintenance of the blood-brain barrier. When there is dysfunction or damage to astrocytes, it can lead to failure of the blood-brain barrier and potentially trigger seizures.

Question 3

Disabling the sodium-potassium pump would cause ion concentration differences across the cell membrane to _______.

Accepted Answer

The answer of Disabling the sodium-potassium pump would cause ion...

Question 4

Two scientists calculated the membrane potential of a neuron using two different equations, the Nernst equation and the Goldman equation.Their calculations gave them slightly different predictions.What is the most likely reason for this difference?
A) The numbers of ions considered in the calculations were different.
B) The scientists measured different numbers of cells.
C) The lipid compositions of the cell membranes that the scientists studied were different.
D) The temperatures of the fluid surrounding the cell membranes were different.
E) The scientists placed their measuring electrodes in slightly different positions.

Accepted Answer

The Nernst equation calculates membrane potential based on the concentration gradient of a single type of ion, while the Goldman equation takes into account multiple ions with different permeabilities. If the scientists used different concentrations or numbers of ions in their calculations, it could lead to slightly different predictions of membrane potential.

Question 5

Neurons and macroglia are similar in that they develop from _______, whereas microglia develop from _______.
A) neuronal stem cells; neural tube cells
B) blood-forming stem cells; gliablasts
C) neuronal stem cells; blood-forming stem cells
D) neuroblasts; gliablasts
E) neural progenitor cells; macroglial progenitor cells

Accepted Answer

Neurons and macroglia (such as astrocytes and oligodendrocytes) develop from neuronal stem cells, which are part of the central nervous system's developmental lineage. Microglia, on the other hand, develop from blood-forming stem cells, also known as hematopoietic stem cells, indicating their origin from the immune system lineage rather than the neural lineage.

Question 6

Once an action potential is initiated, there is a period that must elapse before Na⁺ channels can be activated again to generate another action potential.This is called the _______ period. A) membrane depolarization B) membrane hyperpolarization C) refractory D) undershoot E) after-hyperpolarization

Accepted Answer

During the refractory period, the membrane is unresponsive to a new stimulus due to the inactivation of the Na⁺ channels, which are responsible for generating an action potential. This period allows for the recovery of the ion channels and the restoration of the resting membrane potential.

Question 7

The resting potential occurs when only leak potassium ion channels are open, whereas the membrane becomes hyperpolarized when chemically-gated _______ ion channels open.

Accepted Answer

The answer of The resting potential occurs when only leak...

Question 8

At electrical synapses, membrane proteins called connexins connect the cytoplasm of the two neurons.These structural features result in transmission being fast and _______.

Accepted Answer

The answer of At electrical synapses, membrane proteins called connexins...

Question 9

In the neural tube of a developing vertebrate embryo, neuronal stem cells eventually divide asymmetrically, forming one daughter cell that is a neuronal stem cell and another that is either a neuroblast or a _______.

Accepted Answer

The answer of In the neural tube of a developing...

Question 10

The electrochemical gradient of a given ion determines the movement of that ion across a cell membrane.Based on your knowledge of the normal intra- and extracellular concentrations of Na⁺ and K⁺ ions across a resting membrane, what would you expect to happen when both Na⁺ and K⁺ voltage-gated channels were opened in response to an action potential? A) Na⁺ and K⁺ would both move out of the cell. B) Na⁺ would move into the cell, whereas K⁺ would move out of the cell. C) Na⁺ would move out of the cell, whereas K⁺ would move into the cell. D) Na⁺ and K⁺ would both move into the cell. E) Na⁺ would move out of the cell but K⁺ flow would cease.

Accepted Answer

Normally, the concentration of Na+ is higher outside the cell, and the concentration of K+ is higher inside the cell. When voltage-gated channels open during an action potential, Na+ moves into the cell due to its electrochemical gradient, and K+ moves out of the cell, also following its electrochemical gradient.

Question 11

If the motor neuron leaving the _______ root of the spinal cord is damaged, then the extensor muscle of the leg will not contract as it normally would during the knee-jerk reflex.

Accepted Answer

The answer of If the motor neuron leaving the _______...

Question 12

The resting membrane potential provides a means for a neuron to respond to a stimulus.To maintain the resting potential, neurons rely on ion transporters such as
A) leak channels.
B) passive sodium channels.
C) the sodium−potassium pump.
D) ATP.
E) diffusion channels.

Accepted Answer

The sodium-potassium pump helps maintain the resting potential by actively transporting three sodium ions out of the cell and two potassium ions into the cell, creating an electrochemical gradient. This process requires ATP. Leak channels and diffusion channels do not require active transport and therefore do not contribute to maintaining the resting potential. Passive sodium channels do not exist.

Question 13

Which of the following is not a function of astrocytes?
A) Forming the blood−brain barrier
B) Repairing neurons
C) Insulating axons
D) Taking up released neurotransmitter
E) Releasing neurotransmitters

Accepted Answer

Astrocytes do not insulate axons; this is the function of oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.

Question 14

After examining a patient with a neurological disorder that interferes with walking, a neurologist determines that a Mycoplasma bacterium is causing the destruction of the myelin sheath around the axons in the patient's peripheral nerves.What specific cell type is affected in this patient?
A) Oligodendrocytes
B) Astrocytes
C) Neurons of the peripheral nervous system
D) Schwann cells
E) Microglia

Accepted Answer

Schwann cells are responsible for producing myelin in the peripheral nervous system, so if a Mycoplasma bacterium is causing destruction of the myelin sheath in the patient's peripheral nerves, it is likely that the Schwann cells are being affected.

Question 15

The part of the brain called the _______ would likely be relatively large in a vertebrate with complex movements associated with feeding and locomotion.

Accepted Answer

The answer of The part of the brain called the...

Question 16

If you were a neurobiologist interested in recording in real time the activities of single ion channels, then you might use the technique of _______.

Accepted Answer

The answer of If you were a neurobiologist interested in...

Question 17

The drug pentylenetetrazole (PTZ) blocks the action of the neurotransmitter ______, which has been implicated in Down syndrome.

Accepted Answer

The answer of The drug pentylenetetrazole (PTZ) blocks the action...

Question 18

The _______ toxin causes uncontrolled muscle contraction.

Accepted Answer

The answer of The _______ toxin causes uncontrolled muscle contraction....

Question 19

Damage to the axon hillock of a neuron would most immediately impair
A) the receipt of information from other neurons.
B) regrowth of dendrites.
C) myelin formation.
D) the functioning of most cell organelles.
E) the integration of information and generation of action potentials.

Accepted Answer

The axon hillock is the site where the integration of information from the dendrites occurs and generates action potentials, which are responsible for transmitting signals to other neurons or effectors. Damage to the axon hillock would impair this process, but it would not necessarily affect the receipt of information from other neurons, regrowth of dendrites, myelin formation, or the functioning of most cell organelles.

Question 20

During the withdrawal reflex, sensory neurons transmit action potentials into the dorsal horn of the spinal cord, where they synapse with _______ that send pain information to the brain.

Accepted Answer

The answer of During the withdrawal reflex, sensory neurons transmit...

Quiz 44: Neurons, Glia, and Nervous Systems

In a resting neuron, there is a difference in electrical charge across the cell membrane because

Failure of the blood-brain barrier has been implicated in triggering seizures.Which cells might be involved in failure of the blood-brain barrier?

Disabling the sodium-potassium pump would cause ion concentration differences across the cell membrane to _______.

Two scientists calculated the membrane potential of a neuron using two different equations, the Nernst equation and the Goldman equation.Their calculations gave them slightly different predictions.What is the most likely reason for this difference?

Neurons and macroglia are similar in that they develop from _, whereas microglia develop from _.

Once an action potential is initiated, there is a period that must elapse before Na⁺ channels can be activated again to generate another action potential.This is called the _______ period.

The resting potential occurs when only leak potassium ion channels are open, whereas the membrane becomes hyperpolarized when chemically-gated _______ ion channels open.

At electrical synapses, membrane proteins called connexins connect the cytoplasm of the two neurons.These structural features result in transmission being fast and _______.

In the neural tube of a developing vertebrate embryo, neuronal stem cells eventually divide asymmetrically, forming one daughter cell that is a neuronal stem cell and another that is either a neuroblast or a _______.

If the motor neuron leaving the _______ root of the spinal cord is damaged, then the extensor muscle of the leg will not contract as it normally would during the knee-jerk reflex.

The resting membrane potential provides a means for a neuron to respond to a stimulus.To maintain the resting potential, neurons rely on ion transporters such as

Which of the following is not a function of astrocytes?

After examining a patient with a neurological disorder that interferes with walking, a neurologist determines that a Mycoplasma bacterium is causing the destruction of the myelin sheath around the axons in the patient's peripheral nerves.What specific cell type is affected in this patient?

The part of the brain called the _______ would likely be relatively large in a vertebrate with complex movements associated with feeding and locomotion.

If you were a neurobiologist interested in recording in real time the activities of single ion channels, then you might use the technique of _______.

The drug pentylenetetrazole (PTZ) blocks the action of the neurotransmitter ______, which has been implicated in Down syndrome.

The _______ toxin causes uncontrolled muscle contraction.

Damage to the axon hillock of a neuron would most immediately impair

During the withdrawal reflex, sensory neurons transmit action potentials into the dorsal horn of the spinal cord, where they synapse with _______ that send pain information to the brain.

Quiz 44: Neurons, Glia, and Nervous Systems

In a resting neuron, there is a difference in electrical charge across the cell membrane because

Failure of the blood-brain barrier has been implicated in triggering seizures.Which cells might be involved in failure of the blood-brain barrier?

Disabling the sodium-potassium pump would cause ion concentration differences across the cell membrane to _______.

Two scientists calculated the membrane potential of a neuron using two different equations, the Nernst equation and the Goldman equation.Their calculations gave them slightly different predictions.What is the most likely reason for this difference?

Neurons and macroglia are similar in that they develop from _______, whereas microglia develop from _______.

Once an action potential is initiated, there is a period that must elapse before Na+ channels can be activated again to generate another action potential.This is called the _______ period.

The resting potential occurs when only leak potassium ion channels are open, whereas the membrane becomes hyperpolarized when chemically-gated _______ ion channels open.

At electrical synapses, membrane proteins called connexins connect the cytoplasm of the two neurons.These structural features result in transmission being fast and _______.

In the neural tube of a developing vertebrate embryo, neuronal stem cells eventually divide asymmetrically, forming one daughter cell that is a neuronal stem cell and another that is either a neuroblast or a _______.

If the motor neuron leaving the _______ root of the spinal cord is damaged, then the extensor muscle of the leg will not contract as it normally would during the knee-jerk reflex.

The resting membrane potential provides a means for a neuron to respond to a stimulus.To maintain the resting potential, neurons rely on ion transporters such as

Which of the following is not a function of astrocytes?

After examining a patient with a neurological disorder that interferes with walking, a neurologist determines that a Mycoplasma bacterium is causing the destruction of the myelin sheath around the axons in the patient's peripheral nerves.What specific cell type is affected in this patient?

The part of the brain called the _______ would likely be relatively large in a vertebrate with complex movements associated with feeding and locomotion.

If you were a neurobiologist interested in recording in real time the activities of single ion channels, then you might use the technique of _______.

The drug pentylenetetrazole (PTZ) blocks the action of the neurotransmitter ______, which has been implicated in Down syndrome.

The _______ toxin causes uncontrolled muscle contraction.

Damage to the axon hillock of a neuron would most immediately impair

During the withdrawal reflex, sensory neurons transmit action potentials into the dorsal horn of the spinal cord, where they synapse with _______ that send pain information to the brain.

Neurons and macroglia are similar in that they develop from _, whereas microglia develop from _.

Once an action potential is initiated, there is a period that must elapse before Na⁺ channels can be activated again to generate another action potential.This is called the _______ period.