,BIOL251/BIOL 251 Human Anatomy & Physiology I w/Lab
Module 4 Exam | Portage Learning | 2026 Edition (PDF)
1. Which of the following is the primary functional unit of the nervous system responsible for
transmitting electrical signals?
A) Neuroglia
B) Dendrite
C) Neuron
D) Axon
Correct Answer: Neuron
Rationale: The neuron is the fundamental structural and functional unit of the nervous system,
specialized for receiving, processing, and transmitting electrical and chemical signals. Neuroglia support
neurons but do not transmit impulses. Dendrites and axons are parts of a neuron.
2. Which part of a neuron typically receives signals from other neurons and conducts them toward the
cell body?
A) Axon
B) Dendrite
C) Axon hillock
D) Synaptic terminal
Correct Answer: Dendrite
Rationale: Dendrites are the branched projections of a neuron that receive incoming signals from other
neurons and conduct them toward the cell body (soma). The axon conducts impulses away from the cell
body.
3. What is the name of the junction between two neurons where communication occurs?
A) Synapse
,B) Node of Ranvier
C) Myelin sheath
D) Axon hillock
Correct Answer: Synapse
Rationale: A synapse is the specialized junction between two neurons (or between a neuron and an
effector cell) where neurotransmitters are released to transmit signals. The myelin sheath insulates
axons, and Nodes of Ranvier are gaps in the myelin sheath.
4. Which neuroglial cell produces myelin in the central nervous system?
A) Schwann cell
B) Oligodendrocyte
C) Astrocyte
D) Microglia
Correct Answer: Oligodendrocyte
Rationale: Oligodendrocytes are the myelinating cells of the central nervous system (CNS), forming
myelin sheaths around axons to increase conduction speed. Schwann cells produce myelin in the
peripheral nervous system.
5. The resting membrane potential of a typical neuron is approximately:
A) -70 mV
B) 0 mV
C) +30 mV
D) -55 mV
Correct Answer: -70 mV
, Rationale: The resting membrane potential of a typical neuron is about -70 mV, meaning the inside of
the cell is negatively charged relative to the outside. This is maintained by the sodium-potassium pump
and the selective permeability of the membrane.
6. An action potential is triggered when the membrane potential reaches which value?
A) Resting potential
B) Threshold potential
C) Equilibrium potential
D) Repolarization potential
Correct Answer: Threshold potential
Rationale: An action potential is initiated when the membrane potential reaches the threshold potential
(typically around -55 mV). At this point, voltage-gated sodium channels open, and the neuron fires in an
all-or-none manner.
7. The period during which a neuron cannot generate another action potential, regardless of the
strength of the stimulus, is called the:
A) Refractory period
B) Depolarization phase
C) Repolarization phase
D) Hyperpolarization phase
Correct Answer: Refractory period
Rationale: The refractory period is the brief interval after an action potential during which the neuron is
unable to generate another action potential. This ensures unidirectional propagation and limits the
frequency of impulses.
8. Which neurotransmitter is released at the neuromuscular junction to stimulate skeletal muscle
contraction?
A) Dopamine
Module 4 Exam | Portage Learning | 2026 Edition (PDF)
1. Which of the following is the primary functional unit of the nervous system responsible for
transmitting electrical signals?
A) Neuroglia
B) Dendrite
C) Neuron
D) Axon
Correct Answer: Neuron
Rationale: The neuron is the fundamental structural and functional unit of the nervous system,
specialized for receiving, processing, and transmitting electrical and chemical signals. Neuroglia support
neurons but do not transmit impulses. Dendrites and axons are parts of a neuron.
2. Which part of a neuron typically receives signals from other neurons and conducts them toward the
cell body?
A) Axon
B) Dendrite
C) Axon hillock
D) Synaptic terminal
Correct Answer: Dendrite
Rationale: Dendrites are the branched projections of a neuron that receive incoming signals from other
neurons and conduct them toward the cell body (soma). The axon conducts impulses away from the cell
body.
3. What is the name of the junction between two neurons where communication occurs?
A) Synapse
,B) Node of Ranvier
C) Myelin sheath
D) Axon hillock
Correct Answer: Synapse
Rationale: A synapse is the specialized junction between two neurons (or between a neuron and an
effector cell) where neurotransmitters are released to transmit signals. The myelin sheath insulates
axons, and Nodes of Ranvier are gaps in the myelin sheath.
4. Which neuroglial cell produces myelin in the central nervous system?
A) Schwann cell
B) Oligodendrocyte
C) Astrocyte
D) Microglia
Correct Answer: Oligodendrocyte
Rationale: Oligodendrocytes are the myelinating cells of the central nervous system (CNS), forming
myelin sheaths around axons to increase conduction speed. Schwann cells produce myelin in the
peripheral nervous system.
5. The resting membrane potential of a typical neuron is approximately:
A) -70 mV
B) 0 mV
C) +30 mV
D) -55 mV
Correct Answer: -70 mV
, Rationale: The resting membrane potential of a typical neuron is about -70 mV, meaning the inside of
the cell is negatively charged relative to the outside. This is maintained by the sodium-potassium pump
and the selective permeability of the membrane.
6. An action potential is triggered when the membrane potential reaches which value?
A) Resting potential
B) Threshold potential
C) Equilibrium potential
D) Repolarization potential
Correct Answer: Threshold potential
Rationale: An action potential is initiated when the membrane potential reaches the threshold potential
(typically around -55 mV). At this point, voltage-gated sodium channels open, and the neuron fires in an
all-or-none manner.
7. The period during which a neuron cannot generate another action potential, regardless of the
strength of the stimulus, is called the:
A) Refractory period
B) Depolarization phase
C) Repolarization phase
D) Hyperpolarization phase
Correct Answer: Refractory period
Rationale: The refractory period is the brief interval after an action potential during which the neuron is
unable to generate another action potential. This ensures unidirectional propagation and limits the
frequency of impulses.
8. Which neurotransmitter is released at the neuromuscular junction to stimulate skeletal muscle
contraction?
A) Dopamine
