,PSYC 380 Quiz 2 | Physiological Psychology (2026)
Q&A | Liberty University
1. Which of the following best describes the primary function of the sodium-
potassium pump in maintaining the resting membrane potential?
A) It actively transports three sodium ions out of the cell and two potassium ions
into the cell.
B) It passively diffuses sodium and potassium ions across the membrane.
C) It transports calcium ions into the cell to trigger neurotransmitter release.
D) It pumps chloride ions out of the cell to maintain an electrical gradient.
Correct Answer: It actively transports three sodium ions out of the cell and two
potassium ions into the cell.
Rationale: The sodium-potassium pump uses ATP to move three sodium ions out
and two potassium ions into the neuron, creating the concentration gradients that
underlie the resting potential. Passive diffusion occurs through ion channels, not
the pump. Calcium transport and chloride pumping are not primary functions of
this pump.
2. What is the primary role of the myelin sheath in neural conduction?
A) It increases the speed of action potential propagation through saltatory
conduction.
B) It produces neurotransmitters for synaptic release.
C) It receives incoming signals from other neurons.
D) It stores glucose reserves for neuronal energy.
,Correct Answer: It increases the speed of action potential propagation through
saltatory conduction.
Rationale: Myelin insulates the axon and allows action potentials to jump
between nodes of Ranvier, greatly increasing conduction velocity.
Neurotransmitter production occurs in the cell body, signal reception occurs at
dendrites, and glucose storage is not a primary function of myelin.
3. According to the concept of the blood-brain barrier, which structural component
is primarily responsible for restricting the passage of substances?
A) Tight junctions between capillary endothelial cells.
B) The presence of myelin around cerebral blood vessels.
C) A thick layer of cerebrospinal fluid surrounding the brain.
D) Astrocytic processes that completely envelop all neurons.
Correct Answer: Tight junctions between capillary endothelial cells.
Rationale: The blood-brain barrier is formed by tight junctions between the
endothelial cells of brain capillaries, which prevent most substances from freely
entering the brain. Myelin does not surround blood vessels, cerebrospinal fluid
does not form a barrier, and astrocytes contribute to barrier function but are not
the primary structural component.
4. Which type of glial cell is responsible for forming the myelin sheath in the
peripheral nervous system?
A) Schwann cells
B) Oligodendrocytes
C) Astrocytes
, D) Microglial cells
Correct Answer: Schwann cells
Rationale: Schwann cells are the glial cells that myelinate axons in the
peripheral nervous system. Oligodendrocytes perform this function in the central
nervous system. Astrocytes provide metabolic support and form the blood-brain
barrier, while microglial cells act as immune cells in the CNS.
5. What is the primary function of an oligodendrocyte in the central nervous
system?
A) To form the myelin sheath around axons.
B) To engulf pathogens and remove cellular debris.
C) To circulate cerebrospinal fluid through the ventricles.
D) To form connections between blood vessels and neurons.
Correct Answer: To form the myelin sheath around axons.
Rationale: Oligodendrocytes are the myelinating glial cells of the central
nervous system, wrapping multiple axons with myelin. Microglial cells perform
immune functions, ependymal cells circulate cerebrospinal fluid, and astrocytes
form connections between blood vessels and neurons.
6. Which of the following best describes the all-or-none law as it applies to action
potentials?
A) An action potential occurs only if the stimulus reaches a certain threshold.
B) The size of an action potential varies with the strength of the stimulus.
C) Action potentials can be summed to produce a larger response.
Q&A | Liberty University
1. Which of the following best describes the primary function of the sodium-
potassium pump in maintaining the resting membrane potential?
A) It actively transports three sodium ions out of the cell and two potassium ions
into the cell.
B) It passively diffuses sodium and potassium ions across the membrane.
C) It transports calcium ions into the cell to trigger neurotransmitter release.
D) It pumps chloride ions out of the cell to maintain an electrical gradient.
Correct Answer: It actively transports three sodium ions out of the cell and two
potassium ions into the cell.
Rationale: The sodium-potassium pump uses ATP to move three sodium ions out
and two potassium ions into the neuron, creating the concentration gradients that
underlie the resting potential. Passive diffusion occurs through ion channels, not
the pump. Calcium transport and chloride pumping are not primary functions of
this pump.
2. What is the primary role of the myelin sheath in neural conduction?
A) It increases the speed of action potential propagation through saltatory
conduction.
B) It produces neurotransmitters for synaptic release.
C) It receives incoming signals from other neurons.
D) It stores glucose reserves for neuronal energy.
,Correct Answer: It increases the speed of action potential propagation through
saltatory conduction.
Rationale: Myelin insulates the axon and allows action potentials to jump
between nodes of Ranvier, greatly increasing conduction velocity.
Neurotransmitter production occurs in the cell body, signal reception occurs at
dendrites, and glucose storage is not a primary function of myelin.
3. According to the concept of the blood-brain barrier, which structural component
is primarily responsible for restricting the passage of substances?
A) Tight junctions between capillary endothelial cells.
B) The presence of myelin around cerebral blood vessels.
C) A thick layer of cerebrospinal fluid surrounding the brain.
D) Astrocytic processes that completely envelop all neurons.
Correct Answer: Tight junctions between capillary endothelial cells.
Rationale: The blood-brain barrier is formed by tight junctions between the
endothelial cells of brain capillaries, which prevent most substances from freely
entering the brain. Myelin does not surround blood vessels, cerebrospinal fluid
does not form a barrier, and astrocytes contribute to barrier function but are not
the primary structural component.
4. Which type of glial cell is responsible for forming the myelin sheath in the
peripheral nervous system?
A) Schwann cells
B) Oligodendrocytes
C) Astrocytes
, D) Microglial cells
Correct Answer: Schwann cells
Rationale: Schwann cells are the glial cells that myelinate axons in the
peripheral nervous system. Oligodendrocytes perform this function in the central
nervous system. Astrocytes provide metabolic support and form the blood-brain
barrier, while microglial cells act as immune cells in the CNS.
5. What is the primary function of an oligodendrocyte in the central nervous
system?
A) To form the myelin sheath around axons.
B) To engulf pathogens and remove cellular debris.
C) To circulate cerebrospinal fluid through the ventricles.
D) To form connections between blood vessels and neurons.
Correct Answer: To form the myelin sheath around axons.
Rationale: Oligodendrocytes are the myelinating glial cells of the central
nervous system, wrapping multiple axons with myelin. Microglial cells perform
immune functions, ependymal cells circulate cerebrospinal fluid, and astrocytes
form connections between blood vessels and neurons.
6. Which of the following best describes the all-or-none law as it applies to action
potentials?
A) An action potential occurs only if the stimulus reaches a certain threshold.
B) The size of an action potential varies with the strength of the stimulus.
C) Action potentials can be summed to produce a larger response.
