BIOL251: Human Anatomy & Physiology I w/Lab (2026)
Module 7 Exam: The Nervous System
160 Questions with Correct Answers and Rationales
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1. What is the primary cell type responsible for generating and transmitting electrical impulses in the
nervous system?
A. Astrocytes
B. Oligodendrocytes
C. Neurons
D. Ependymal cells
Correct Answer: C. Neurons
Rationale: Neurons are the excitable cells of the nervous system that conduct action potentials. Glial
cells (like astrocytes, oligodendrocytes, and ependymal cells) provide support, protection, and
nourishment .
2. Which part of a neuron typically receives signals from other neurons?
A. Axon
B. Axon terminal
C. Dendrites
D. Myelin sheath
Correct Answer: C. Dendrites
,Rationale: Dendrites are highly branched projections that act as the main receivers of incoming signals,
conducting them toward the cell body (soma) .
3. The axon hillock is significant because it is the region where:
A. Neurotransmitters are stored
B. The axon terminates at a synapse
C. Action potentials are initiated
D. Dendrites branch from the cell body
Correct Answer: C. Action potentials are initiated
Rationale: The axon hillock is the cone-shaped area where the axon joins the cell body. It has a high
density of voltage-gated sodium channels and is the site where the action potential is generated if the
threshold is reached.
4. Which type of glial cell is responsible for forming the myelin sheath in the central nervous system
(CNS)?
A. Schwann cells
B. Satellite cells
C. Oligodendrocytes
D. Microglia
Correct Answer: C. Oligodendrocytes
Rationale: Oligodendrocytes are the myelinating glia of the CNS. In the peripheral nervous system (PNS),
this function is performed by Schwann cells .
5. What is the primary function of astrocytes?
A. To produce cerebrospinal fluid
B. To maintain the blood-brain barrier and support neurons
,C. To phagocytize pathogens and debris
D. To form the myelin sheath
Correct Answer: B. To maintain the blood-brain barrier and support neurons
Rationale: Astrocytes have numerous functions, including regulating the chemical environment around
neurons, providing nutrients, and forming the structural basis of the blood-brain barrier .
6. The resting membrane potential of a typical neuron is approximately:
A. +30 mV
B. 0 mV
C. -70 mV
D. -90 mV
Correct Answer: C. -70 mV
Rationale: The resting membrane potential is the voltage difference across the membrane when the cell
is not stimulated. It is maintained by the sodium-potassium pump and leak channels, typically around -
70 mV.
7. During depolarization, which ion channels open, causing the membrane potential to become more
positive?
A. Potassium channels
B. Chloride channels
C. Voltage-gated sodium channels
D. Calcium channels
Correct Answer: C. Voltage-gated sodium channels
Rationale: When a stimulus reaches threshold, voltage-gated sodium channels open. The influx of
positive sodium ions (Na+) causes the membrane potential to rapidly rise toward +30 mV.
, 8. What is the role of the sodium-potassium pump (Na+/K+ ATPase) in maintaining resting membrane
potential?
A. It pumps 3 Na+ out and 2 K+ in, using ATP
B. It pumps 2 Na+ out and 3 K+ in, using ATP
C. It allows Na+ and K+ to leak down their gradients
D. It transports Na+ and K+ equally in both directions
Correct Answer: A. It pumps 3 Na+ out and 2 K+ in, using ATP
Rationale: This active transport mechanism helps maintain the concentration gradients essential for the
resting potential, making the inside of the cell more negative relative to the outside .
9. The period during which a neuron cannot generate another action potential, no matter how strong
the stimulus, is called the:
A. Depolarization phase
B. Relative refractory period
C. Absolute refractory period
D. Repolarization phase
Correct Answer: C. Absolute refractory period
Rationale: During the absolute refractory period, the voltage-gated sodium channels are either open or
inactivated, making it impossible to initiate another action potential.
10. An action potential is conducted more rapidly in axons that are:
A. Thin and unmyelinated
B. Thin and myelinated
C. Thick and unmyelinated
D. Thick and myelinated
Module 7 Exam: The Nervous System
160 Questions with Correct Answers and Rationales
Portage Learning | LockDown Browser Format
1. What is the primary cell type responsible for generating and transmitting electrical impulses in the
nervous system?
A. Astrocytes
B. Oligodendrocytes
C. Neurons
D. Ependymal cells
Correct Answer: C. Neurons
Rationale: Neurons are the excitable cells of the nervous system that conduct action potentials. Glial
cells (like astrocytes, oligodendrocytes, and ependymal cells) provide support, protection, and
nourishment .
2. Which part of a neuron typically receives signals from other neurons?
A. Axon
B. Axon terminal
C. Dendrites
D. Myelin sheath
Correct Answer: C. Dendrites
,Rationale: Dendrites are highly branched projections that act as the main receivers of incoming signals,
conducting them toward the cell body (soma) .
3. The axon hillock is significant because it is the region where:
A. Neurotransmitters are stored
B. The axon terminates at a synapse
C. Action potentials are initiated
D. Dendrites branch from the cell body
Correct Answer: C. Action potentials are initiated
Rationale: The axon hillock is the cone-shaped area where the axon joins the cell body. It has a high
density of voltage-gated sodium channels and is the site where the action potential is generated if the
threshold is reached.
4. Which type of glial cell is responsible for forming the myelin sheath in the central nervous system
(CNS)?
A. Schwann cells
B. Satellite cells
C. Oligodendrocytes
D. Microglia
Correct Answer: C. Oligodendrocytes
Rationale: Oligodendrocytes are the myelinating glia of the CNS. In the peripheral nervous system (PNS),
this function is performed by Schwann cells .
5. What is the primary function of astrocytes?
A. To produce cerebrospinal fluid
B. To maintain the blood-brain barrier and support neurons
,C. To phagocytize pathogens and debris
D. To form the myelin sheath
Correct Answer: B. To maintain the blood-brain barrier and support neurons
Rationale: Astrocytes have numerous functions, including regulating the chemical environment around
neurons, providing nutrients, and forming the structural basis of the blood-brain barrier .
6. The resting membrane potential of a typical neuron is approximately:
A. +30 mV
B. 0 mV
C. -70 mV
D. -90 mV
Correct Answer: C. -70 mV
Rationale: The resting membrane potential is the voltage difference across the membrane when the cell
is not stimulated. It is maintained by the sodium-potassium pump and leak channels, typically around -
70 mV.
7. During depolarization, which ion channels open, causing the membrane potential to become more
positive?
A. Potassium channels
B. Chloride channels
C. Voltage-gated sodium channels
D. Calcium channels
Correct Answer: C. Voltage-gated sodium channels
Rationale: When a stimulus reaches threshold, voltage-gated sodium channels open. The influx of
positive sodium ions (Na+) causes the membrane potential to rapidly rise toward +30 mV.
, 8. What is the role of the sodium-potassium pump (Na+/K+ ATPase) in maintaining resting membrane
potential?
A. It pumps 3 Na+ out and 2 K+ in, using ATP
B. It pumps 2 Na+ out and 3 K+ in, using ATP
C. It allows Na+ and K+ to leak down their gradients
D. It transports Na+ and K+ equally in both directions
Correct Answer: A. It pumps 3 Na+ out and 2 K+ in, using ATP
Rationale: This active transport mechanism helps maintain the concentration gradients essential for the
resting potential, making the inside of the cell more negative relative to the outside .
9. The period during which a neuron cannot generate another action potential, no matter how strong
the stimulus, is called the:
A. Depolarization phase
B. Relative refractory period
C. Absolute refractory period
D. Repolarization phase
Correct Answer: C. Absolute refractory period
Rationale: During the absolute refractory period, the voltage-gated sodium channels are either open or
inactivated, making it impossible to initiate another action potential.
10. An action potential is conducted more rapidly in axons that are:
A. Thin and unmyelinated
B. Thin and myelinated
C. Thick and unmyelinated
D. Thick and myelinated
