The brain and spinal cord together make up which part of the nervous system?
Central nervous system
✓
Peripheral nervous system
Somatic nervous system
Enteric nervous system
Correct Answer
Central nervous system
The central nervous system is the brain and spinal cord, the main site of integration. The peripheral nervous system is everything outside the brain and spinal cord, such as nerves and ganglia. The somatic nervous system is a functional division for conscious perception and voluntary movement, not an anatomical region. The enteric nervous system is the network controlling the digestive tract.
Category: Organization of the Nervous System
Question 2
What is a cluster of neuron cell bodies located in the peripheral nervous system called?
Nucleus
Ganglion
✓
Tract
Nerve
Correct Answer
Ganglion
A ganglion is a collection of neuron cell bodies outside the brain and spinal cord. Nucleus is the term for a cluster of cell bodies within the central nervous system. Tract is a bundle of axons in the central nervous system. Nerve is a bundle of axons in the peripheral nervous system.
Category: Organization of the Nervous System
Question 3
What is a bundle of axons running within the brain or spinal cord called?
Nerve
Ganglion
Tract
✓
Nucleus
Correct Answer
Tract
Within the central nervous system, a bundle of axons is called a tract. Nerve is the name for an axon bundle in the peripheral nervous system. Ganglion refers to a group of cell bodies in the peripheral nervous system. Nucleus refers to a group of cell bodies in the central nervous system.
Category: Organization of the Nervous System
Question 4
Which region of brain and spinal cord tissue consists mostly of neuron cell bodies and dendrites?
White matter
Dura mater
Choroid plexus
Gray matter
✓
Correct Answer
Gray matter
Gray matter is made up mainly of neuron cell bodies and dendrites, which lack the pale myelin covering. White matter consists mostly of myelinated axons, which give it a white appearance. Dura mater is a tough protective membrane around the brain and spinal cord, not neural tissue. Choroid plexus is a vascular structure in the ventricles that helps make cerebrospinal fluid.
Category: Organization of the Nervous System
Question 5
Which functional division of the nervous system provides involuntary control of smooth muscle, cardiac muscle and glands?
Autonomic nervous system
✓
Somatic nervous system
Central nervous system
Peripheral nervous system
Correct Answer
Autonomic nervous system
The autonomic nervous system regulates smooth muscle, cardiac muscle and glands without conscious control, largely to maintain homeostasis. The somatic nervous system handles conscious perception and voluntary control of skeletal muscle. Central nervous system is an anatomical division, the brain and spinal cord. Peripheral nervous system is also an anatomical division rather than a functional one.
Category: Organization of the Nervous System
Question 6
Which glial cell wraps segments of several different axons with myelin inside the brain and spinal cord?
Schwann cell
Oligodendrocyte
✓
Astrocyte
Microglia
Correct Answer
Oligodendrocyte
An oligodendrocyte extends several processes, each of which can myelinate a segment of a different axon in the central nervous system. Schwann cell myelinates axons in the peripheral nervous system and covers only one axon segment. Astrocyte supports neurons and helps form the blood-brain barrier but does not make myelin. Microglia are phagocytic immune cells, not myelin producers.
Category: Glial Cells
Question 7
In peripheral nerves, which glial cell wraps a single axon segment with myelin?
Satellite cell
Ependymal cell
Schwann cell
✓
Oligodendrocyte
Correct Answer
Schwann cell
A Schwann cell wraps around one segment of one axon in the peripheral nervous system, forming its myelin sheath. Satellite cell surrounds neuron cell bodies in peripheral ganglia and does not form myelin. Ependymal cell lines the brain ventricles and spinal canal. Oligodendrocyte forms myelin in the central nervous system and can cover segments of several axons.
Category: Glial Cells
Question 8
Which star-shaped glial cell helps maintain the blood-brain barrier and regulate the chemical environment around neurons?
Microglia
Ependymal cell
Satellite cell
Astrocyte
✓
Correct Answer
Astrocyte
Astrocytes are star-shaped central nervous system glia that buffer the extracellular fluid, remove excess signaling molecules and contribute to the blood-brain barrier. Microglia are phagocytes that defend nervous tissue. Ependymal cell lines the ventricles and helps produce cerebrospinal fluid. Satellite cell is a peripheral glial cell found around cell bodies in ganglia.
Category: Glial Cells
Question 9
In a typical multipolar neuron, where are action potentials normally generated?
Initial segment of the axon
✓
Distal dendrites
Nucleus of the soma
Synaptic end bulbs
Correct Answer
Initial segment of the axon
The axon hillock and initial segment form the trigger zone, where a high density of voltage-gated sodium channels lets graded potentials start an action potential. Distal dendrites produce graded potentials, not action potentials. Nucleus of the soma holds genetic material and does not generate electrical signals. Synaptic end bulbs are where an arriving action potential triggers neurotransmitter release.
Category: Neuron Structure
Question 10
A neuron with exactly one axon and one dendrite, such as those in the retina and olfactory epithelium, is classified as which type?
Unipolar
Bipolar
✓
Multipolar
Anaxonic
Correct Answer
Bipolar
Bipolar neurons have two processes, one axon and one dendrite, and are found mainly in the retina and the olfactory epithelium. Unipolar neurons have a single process and in humans are sensory neurons. Multipolar neurons have one axon and two or more dendrites. Anaxonic describes neurons with no distinguishable axon.
Category: Neuron Structure
Question 11
What is the typical resting membrane potential of a neuron?
+30 mV
-55 mV
-70 mV
✓
0 mV
Correct Answer
-70 mV
A typical neuron at rest holds its inside at about -70 mV relative to the outside, set by ion concentration gradients and leakage channels. -55 mV is the usual threshold that triggers an action potential. +30 mV is roughly the peak of an action potential. 0 mV would mean no charge difference across the membrane, which is not the resting state.
Category: Resting Membrane Potential
Question 12
During the depolarization phase of an action potential, which ion rushes into the neuron?
Potassium
Chloride
Calcium
Sodium
✓
Correct Answer
Sodium
When threshold is reached, voltage-gated sodium channels open and sodium ions flow in down their concentration gradient, making the inside of the cell positive. Potassium leaves the cell during repolarization. Chloride entry hyperpolarizes a membrane rather than depolarizing it. Calcium entry at the axon terminal triggers neurotransmitter release but does not drive the axonal action potential.
Category: Action Potential
Question 13
Which ion leaves the neuron through voltage-gated channels to return the membrane toward its resting value after the peak of an action potential?
Potassium
✓
Sodium
Calcium
Chloride
Correct Answer
Potassium
Repolarization occurs as voltage-gated potassium channels open and potassium ions flow out, restoring a negative interior. Sodium flows inward during depolarization, not outward during repolarization. Calcium enters axon terminals to trigger vesicle release. Chloride is an anion whose entry hyperpolarizes cells at inhibitory synapses.
Category: Action Potential
Question 14
During the absolute refractory period, why can a second action potential not be started?
Potassium channels have not yet opened
Sodium channel inactivation gates are closed
✓
The membrane is still at resting potential
Neurotransmitter stores are depleted
Correct Answer
Sodium channel inactivation gates are closed
From the moment voltage-gated sodium channels open until they reset, the sodium channels are either already open or held shut by their inactivation gates, which cannot reopen until the membrane repolarizes, so no stimulus of any strength can trigger a new action potential. Potassium channels have not yet opened is incorrect because the state of potassium channels is not what blocks a new action potential, and they do open during the falling phase of this period. The membrane is still at resting potential is incorrect because the membrane is depolarized or repolarizing. Neurotransmitter stores are depleted describes the synapse, not the axonal membrane.
Category: Action Potential
Question 15
In a myelinated axon, the action potential appears to jump from one node of Ranvier to the next. What is this type of propagation called?
Continuous conduction
Spatial summation
Saltatory conduction
✓
Temporal summation
Correct Answer
Saltatory conduction
Saltatory conduction occurs because myelin insulates the internodes, so the action potential is regenerated only at the nodes, which speeds propagation. Continuous conduction happens in unmyelinated axons, where every adjacent patch of membrane depolarizes in turn. Spatial summation is the adding of graded potentials from different locations. Temporal summation is the adding of graded potentials that arrive in rapid succession.
Category: Propagation
Question 16
Besides myelination, which axon feature most increases the speed at which an action potential travels?
Shorter dendrites
More axon terminals
Smaller cell body
Larger diameter
✓
Correct Answer
Larger diameter
A wider axon offers less internal resistance to current flow, so the depolarization spreads farther and faster. Shorter dendrites affect where input is received, not axonal conduction speed. More axon terminals increase the number of target cells but do not speed the signal. Smaller cell body has no direct effect on how fast the axon conducts.
Category: Propagation
Question 17
When an action potential reaches the axon terminal, voltage-gated channels open for which ion, causing synaptic vesicles to release neurotransmitter?
Calcium
✓
Sodium
Potassium
Chloride
Correct Answer
Calcium
Calcium ions enter the synaptic end bulb through voltage-gated channels and cause vesicles to fuse with the presynaptic membrane and release neurotransmitter by exocytosis. Sodium carries the depolarization along the axon but does not directly trigger vesicle fusion. Potassium efflux repolarizes the membrane. Chloride is involved in inhibitory postsynaptic responses.
Category: Synaptic Transmission
Question 18
Which enzyme breaks down acetylcholine in the synaptic cleft, ending its signal?
Monoamine oxidase
Acetylcholinesterase
✓
Adenylate cyclase
Phospholipase C
Correct Answer
Acetylcholinesterase
Acetylcholinesterase in the synaptic cleft rapidly splits acetylcholine, stopping its action on the postsynaptic receptors. Monoamine oxidase breaks down biogenic amines such as norepinephrine and serotonin. Adenylate cyclase is an effector enzyme that produces the second messenger cAMP. Phospholipase C is an effector enzyme that produces IP3.
Category: Synaptic Transmission
Question 19
What is a hyperpolarizing change in the postsynaptic membrane that moves it farther from threshold called?
Excitatory postsynaptic potential
Generator potential
Inhibitory postsynaptic potential
✓
End plate potential
Correct Answer
Inhibitory postsynaptic potential
An inhibitory postsynaptic potential makes the membrane more negative, often through chloride entry or potassium exit, so the cell is less likely to fire. Excitatory postsynaptic potential depolarizes the membrane toward threshold. Generator potential is a graded potential in a sensory neuron that can trigger an action potential in that same cell. End plate potential is the depolarization of a skeletal muscle fiber at the neuromuscular junction.
Category: Synaptic Transmission
Question 20
What is a neurotransmitter receptor that acts through a G protein and a second messenger, rather than forming an ion channel itself, called?
Ionotropic receptor
Nicotinic receptor
Ligand-gated channel
Metabotropic receptor
✓
Correct Answer
Metabotropic receptor
A metabotropic receptor activates a G protein, which turns on an effector enzyme that makes a second messenger such as cAMP or IP3. Ionotropic receptor is itself an ion channel that opens when the neurotransmitter binds. Nicotinic receptor is an acetylcholine receptor that is an ionotropic cation channel. Ligand-gated channel is another name for an ionotropic receptor.
Category: Neurotransmitters and Receptors