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The Nervous System - MCAT Practice Questions
Neurons that ascend the spinal cord and carry sensory information from the
periphery to the brain are classified as: Afferent neurons
Which component of the central nervous system (CNS) is primarily composed of
myelinated axons and is named for its pale appearance? White matter
Which type of glial cell is responsible for forming the myelin sheath around
axons in the peripheral nervous system (PNS)? Schwann cells
The sympathetic nervous system is primarily responsible for which of the
following physiological responses? Fight or flight
Neurons that transmit impulses between other neurons, especially integrating
sensory and motor pathways within the CNS, are called: Interneurons
Which glial cell type forms the crucial blood-brain barrier that regulates
the movement of solutes from the bloodstream into the nervous tissue? Astrocytes
What is the concentration gradient for Na⁺ ions across the cell membrane at
the neuron's resting potential? Higher outside the cell
During an action potential, the peak voltage reached upon full
depolarization is approximately: +40 mV
Depolarization of the neuronal membrane is caused by the flow of: Na⁺ ions into the cell
The phase of the action potential where the membrane potential momentarily
dips below the resting potential (e.g., below -70 mV) is known as: Hyperpolarization
The Na⁺/K⁺ pump restores the ion concentration gradients by moving which
combination of ions? 3 Na⁺ out, 2 K⁺ in
Compared to Na⁺, the cell membrane at rest is: Highly permeable to K⁺
The statement that the amplitude of an action potential is independent of
the amount of current that produced it is a description of which
principle? The all-or-nothing principle
When multiple presynaptic neurons simultaneously release neurotransmitters
that collectively bring the postsynaptic cell to threshold, this process is
known as: Spatial summation
An Excitatory Postsynaptic Potential (EPSP) causes the membrane of the
postsynaptic neuron to: Depolarize
At a chemical synapse, the influx of which ion into the presynaptic terminal
is directly responsible for triggering the fusion of neurotransmitter
vesicles with the cell membrane? Ca²⁺
Which of the following describes a key difference between electrical and
chemical synapses? Electrical synapses are connected by gap junctions; chemical synapses use
neurotransmitters
The signal in a synapse can be terminated by all of the following mechanisms
EXCEPT: Reuptake of neurotransmitter by the postsynaptic neuron
An Inhibitory Postsynaptic Potential (IPSP) causes the membrane of the
postsynaptic neuron to: Hyperpolarize
Which of the following channels is involved in allowing Ca²⁺ to enter the
presynaptic cell? Voltage-gated Ca²⁺ channels
The main inhibitory neurotransmitter found in the brain is: GABA
Which neurotransmitter is the main excitatory transmitter in the central
nervous system (CNS)? Glutamate
Receptors that operate via indirect neurotransmitter action, where binding
triggers a signaling pathway that may then open or close ion channels, are
classified as: G-protein coupled receptors (a type of metabotropic receptor)
The main inhibitory neurotransmitter found in the spinal cord is: Glycine
Ionotropic receptors mediate neurotransmitter action that is: Direct, fast, and local