00000 N138 Midterm Samuel
Merritt University Questions With
Complete Solutions
Course
N138
1) What is the primary function of the sodium-potassium pump in neurons?
Answer: Maintains resting membrane potential by pumping 3 Na⁺ ions out and 2 K⁺ ions in.
Solution/Rationale: This active transport creates the electrochemical gradient necessary for
action potentials and neuronal signaling.
2) How does an action potential propagate along an axon?
Answer: Via sequential depolarization and repolarization of the axonal membrane.
Solution/Rationale: Voltage-gated Na⁺ channels open to depolarize the membrane, then K⁺
channels repolarize it, allowing the signal to move along the axon.
3) What role does myelin play in the nervous system?
Answer: Increases conduction velocity of action potentials via saltatory conduction.
Solution/Rationale: Myelin insulates axons and forces the action potential to jump between
nodes of Ranvier, speeding transmission.
4) How do excitatory and inhibitory neurotransmitters affect postsynaptic neurons?
Answer: Excitatory neurotransmitters depolarize the membrane, while inhibitory
neurotransmitters hyperpolarize it.
Solution/Rationale: Excitatory signals increase the likelihood of an action potential; inhibitory
signals decrease it.
5) What is the function of the cerebellum in motor control?
Answer: Coordinates voluntary movements, balance, and posture.
Solution/Rationale: The cerebellum integrates sensory input and motor commands to ensure
smooth, precise motion.
,6) How does synaptic plasticity contribute to learning and memory?
Answer: By strengthening or weakening synaptic connections based on activity patterns.
Solution/Rationale: Long-term potentiation (LTP) and long-term depression (LTD) modify
synapse efficiency, forming the basis of memory and learning.
7) What is the significance of the blood-brain barrier?
Answer: Protects the brain from toxins and pathogens while allowing essential nutrients to pass.
Solution/Rationale: Tight junctions in endothelial cells selectively regulate substance entry,
maintaining CNS homeostasis.
8) How does the hypothalamus regulate homeostasis?
Answer: By controlling hormone release, body temperature, hunger, thirst, and circadian
rhythms.
Solution/Rationale: Integrates signals from the nervous and endocrine systems to maintain
internal stability.
9) What is the difference between gray matter and white matter in the CNS?
Answer: Gray matter contains neuronal cell bodies; white matter contains myelinated axons.
Solution/Rationale: Gray matter processes information, while white matter transmits signals
between CNS regions.
10) How does an inhibitory postsynaptic potential (IPSP) affect neuronal activity?
Answer: Hyperpolarizes the postsynaptic membrane, making it less likely to fire an action
potential.
Solution/Rationale: IPSPs increase membrane potential negativity, counteracting excitatory
inputs and regulating neuronal excitability.
11) What is the function of the nodes of Ranvier?
Answer: Facilitate rapid conduction of action potentials along myelinated axons.
Solution/Rationale: By allowing the action potential to jump from node to node (saltatory
conduction), the transmission speed increases significantly.
12) How does a graded potential differ from an action potential?
, Answer: Graded potentials vary in magnitude and decay with distance; action potentials are all-
or-nothing and propagate without decrement.
Solution/Rationale: Graded potentials are used for local signaling, while action potentials carry
information over long distances.
13) What is the role of calcium ions in neurotransmitter release?
Answer: Calcium influx at the presynaptic terminal triggers synaptic vesicle fusion and
neurotransmitter release.
Solution/Rationale: Voltage-gated Ca²⁺ channels open during depolarization, initiating
exocytosis of neurotransmitters into the synaptic cleft.
14) How do GABA and glutamate differ in their effects on neurons?
Answer: GABA is inhibitory, hyperpolarizing neurons; glutamate is excitatory, depolarizing
neurons.
Solution/Rationale: GABA reduces the likelihood of action potentials, while glutamate
increases it, balancing CNS activity.
15) What is the function of the medulla oblongata?
Answer: Controls autonomic functions such as heart rate, breathing, and blood pressure.
Solution/Rationale: As part of the brainstem, the medulla regulates vital involuntary functions
necessary for survival.
16) How do astrocytes support neuronal function?
Answer: By maintaining extracellular ion balance, recycling neurotransmitters, and supporting
the blood-brain barrier.
Solution/Rationale: Astrocytes provide metabolic and structural support, ensuring optimal
neuronal signaling and CNS homeostasis.
17) What is the effect of hyperpolarization on neuronal excitability?
Answer: Makes the membrane potential more negative, reducing the likelihood of firing an
action potential.
Solution/Rationale: Hyperpolarization increases the distance from the threshold potential,
decreasing neuronal responsiveness.
Merritt University Questions With
Complete Solutions
Course
N138
1) What is the primary function of the sodium-potassium pump in neurons?
Answer: Maintains resting membrane potential by pumping 3 Na⁺ ions out and 2 K⁺ ions in.
Solution/Rationale: This active transport creates the electrochemical gradient necessary for
action potentials and neuronal signaling.
2) How does an action potential propagate along an axon?
Answer: Via sequential depolarization and repolarization of the axonal membrane.
Solution/Rationale: Voltage-gated Na⁺ channels open to depolarize the membrane, then K⁺
channels repolarize it, allowing the signal to move along the axon.
3) What role does myelin play in the nervous system?
Answer: Increases conduction velocity of action potentials via saltatory conduction.
Solution/Rationale: Myelin insulates axons and forces the action potential to jump between
nodes of Ranvier, speeding transmission.
4) How do excitatory and inhibitory neurotransmitters affect postsynaptic neurons?
Answer: Excitatory neurotransmitters depolarize the membrane, while inhibitory
neurotransmitters hyperpolarize it.
Solution/Rationale: Excitatory signals increase the likelihood of an action potential; inhibitory
signals decrease it.
5) What is the function of the cerebellum in motor control?
Answer: Coordinates voluntary movements, balance, and posture.
Solution/Rationale: The cerebellum integrates sensory input and motor commands to ensure
smooth, precise motion.
,6) How does synaptic plasticity contribute to learning and memory?
Answer: By strengthening or weakening synaptic connections based on activity patterns.
Solution/Rationale: Long-term potentiation (LTP) and long-term depression (LTD) modify
synapse efficiency, forming the basis of memory and learning.
7) What is the significance of the blood-brain barrier?
Answer: Protects the brain from toxins and pathogens while allowing essential nutrients to pass.
Solution/Rationale: Tight junctions in endothelial cells selectively regulate substance entry,
maintaining CNS homeostasis.
8) How does the hypothalamus regulate homeostasis?
Answer: By controlling hormone release, body temperature, hunger, thirst, and circadian
rhythms.
Solution/Rationale: Integrates signals from the nervous and endocrine systems to maintain
internal stability.
9) What is the difference between gray matter and white matter in the CNS?
Answer: Gray matter contains neuronal cell bodies; white matter contains myelinated axons.
Solution/Rationale: Gray matter processes information, while white matter transmits signals
between CNS regions.
10) How does an inhibitory postsynaptic potential (IPSP) affect neuronal activity?
Answer: Hyperpolarizes the postsynaptic membrane, making it less likely to fire an action
potential.
Solution/Rationale: IPSPs increase membrane potential negativity, counteracting excitatory
inputs and regulating neuronal excitability.
11) What is the function of the nodes of Ranvier?
Answer: Facilitate rapid conduction of action potentials along myelinated axons.
Solution/Rationale: By allowing the action potential to jump from node to node (saltatory
conduction), the transmission speed increases significantly.
12) How does a graded potential differ from an action potential?
, Answer: Graded potentials vary in magnitude and decay with distance; action potentials are all-
or-nothing and propagate without decrement.
Solution/Rationale: Graded potentials are used for local signaling, while action potentials carry
information over long distances.
13) What is the role of calcium ions in neurotransmitter release?
Answer: Calcium influx at the presynaptic terminal triggers synaptic vesicle fusion and
neurotransmitter release.
Solution/Rationale: Voltage-gated Ca²⁺ channels open during depolarization, initiating
exocytosis of neurotransmitters into the synaptic cleft.
14) How do GABA and glutamate differ in their effects on neurons?
Answer: GABA is inhibitory, hyperpolarizing neurons; glutamate is excitatory, depolarizing
neurons.
Solution/Rationale: GABA reduces the likelihood of action potentials, while glutamate
increases it, balancing CNS activity.
15) What is the function of the medulla oblongata?
Answer: Controls autonomic functions such as heart rate, breathing, and blood pressure.
Solution/Rationale: As part of the brainstem, the medulla regulates vital involuntary functions
necessary for survival.
16) How do astrocytes support neuronal function?
Answer: By maintaining extracellular ion balance, recycling neurotransmitters, and supporting
the blood-brain barrier.
Solution/Rationale: Astrocytes provide metabolic and structural support, ensuring optimal
neuronal signaling and CNS homeostasis.
17) What is the effect of hyperpolarization on neuronal excitability?
Answer: Makes the membrane potential more negative, reducing the likelihood of firing an
action potential.
Solution/Rationale: Hyperpolarization increases the distance from the threshold potential,
decreasing neuronal responsiveness.
