All Questions: 211-240
211. After a gunshot wound, a patient has near-total damage to the right side of her spinal cord at the level of C4. Which of the following outcomes is she most likely to experience?
- A. weakness or paralysis on the left side of her body below the injury
- B. loss of proprioception on the left side of her body below the injury
- C. loss of touch sensations on the left side of her body below the injury
- D. loss of pain sensations on the left side of the body below the injury
Show Answer
Correct answer: D
The patient has experienced a hemisection of the spinal cord, which would typically result in Brown-Sequard syndrome. That would cause weakness/paralysis and deficits in touch, proprioception, and vibration sense on the same side of the body below the injury. She would experience deficits in pain and temperature sensation on the opposite side of the body below the injury.
212. This term is used to refer to the pointed, lower end of the spinal cord:
- A. conus medullaris
- B. cauda equina
- C. foramen magnum
- D. filum terminale
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Correct answer: A
The conus medullaris is the tapered, cone-shaped lower end of the spinal cord. In adults, it typically ends around the L1–L2 vertebral level, although there's some variation. Below this point, the spinal cord transitions into the cauda equina, a bundle of spinal nerves descending within the vertebral canal.
213. In brain blood vessels, which cells form the tight junctions that are the main structural feature of the blood-brain barrier?
- A. glial cells
- B. smooth muscle cells
- C. endothelial cells
- D. oligodendrocytes
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Correct answer: C
Endothelial cells line the interior of brain capillaries and form tight junctions, which are the main structural feature of the blood-brain barrier (BBB). These junctions limit the movement of substances between blood and brain tissue, helping protect the brain from toxins, pathogens, and fluctuations in blood composition.
214. The withdrawal reflex begins with these types of receptors:
- A. photoreceptors
- B. nociceptors
- C. baroreceptors
- D. chemoreceptors
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Correct answer: B
Nociceptors are sensory receptors that detect painful or noxious stimuli. This is the critical first step in the withdrawal reflex, where a signal is sent from the nociceptors to the spinal cord, triggering a rapid, involuntary withdrawal of the body part from the source of the pain.
215. Zolpidem, commonly known by the brand name Ambien, is a drug that promotes sleep primarily by increasing activity at these neurotransmitter receptors:
- A. serotonin
- B. dopamine
- C. glutamate
- D. GABA
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Correct answer: D
Zolpidem exerts its effects by increasing activity at receptors for the neurotransmitter GABA. GABA is primarily an inhibitory neurotransmitter, and increasing GABA activity can promote sleep as GABA can decrease activity in parts of the brain that promote wakefulness.
216. In an electrical synapse, neurons communicate at a specialized region called a:
- A. synaptosome
- B. neurofibril node
- C. gap junction
- D. synaptic hillock
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Correct answer: C
Neurons in an electrical synapse communicate through gap junctions, which allow ions to pass directly between cells, enabling rapid, bidirectional signal transmission.
217. The membrane potential of a neuron changes from -70 mV to -60 mV. This type of change is referred to as:
- A. depolarization
- B. hyperpolarization
- C. repolarization
- D. unpolarization
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Correct answer: A
When the membrane potential becomes less negative (e.g., goes from –70 mV to –60 mV), this is called depolarization. Depolarization increases the likelihood a neuron will fire an action potential.
218. After a stroke, a patient is able to understand language but has great difficulty speaking. She can only produce one word at a time and speaks in short, fragmented sentences. Damage to which area of the brain below is most likely responsible for her symptoms?
- A. Wernicke's area
- B. primary auditory cortex
- C. Broca's area
- D. angular gyrus
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Correct answer: C
Broca’s area is primarily involved in speech production. Damage to this region can result in Broca’s aphasia, which is characterized by difficulty forming complete sentences and speaking fluently, despite relatively preserved language comprehension.
219. Which neurotransmitter is most commonly released by postganglionic neurons of the sympathetic nervous system?
- A. norepinephrine
- B. dopamine
- C. acetylcholine
- D. serotonin
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Correct answer: A
Postganglionic sympathetic neurons typically release norepinephrine, which acts on adrenergic receptors in target tissues. An important exception is sweat glands, where acetylcholine is released instead.
220. What change occurs in a rod photoreceptor when it is exposed to light, initiating the visual signal to the brain?
- A. It becomes depolarized and releases more neurotransmitter
- B. It becomes hyperpolarized and releases less neurotransmitter
- C. It becomes hyperpolarized and releases more neurotransmitter
- D. It becomes depolarized and releases less neurotransmitter
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Correct answer: B
In darkness, rod photoreceptors are depolarized and continuously release the neurotransmitter glutamate. When exposed to light, a phototransduction cascade is triggered that leads to the closure of sodium channels, causing the cell to hyperpolarize. This hyperpolarization reduces glutamate release, which is the key signal that initiates changes in downstream retinal cells and ultimately leads to visual perception.
221. Which of the following structures/systems is most commonly affected in cases of vertigo?
- A. olfactory cortex
- B. vestibular system
- C. motor cortex
- D. auditory cortex
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Correct answer: B
The vestibular system, which includes structures in the inner ear and their connections to the brain, plays a key role in balance and a sense of stability. Vertigo is typically associated with a disruption in function of either the vestibular system or one of the regions it communicates with to maintain our sense of balance.
222. Which of the following terms refers to the region where optic nerve fibers from both eyes partially cross and reorganize to form the optic tracts?
- A. lateral geniculate nucleus
- B. superior colliculus
- C. visual cortex
- D. optic chiasm
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Correct answer: D
At the optic chiasm, fibers from the nasal (medial) half of each retina cross to the opposite side, while fibers from the temporal (lateral) halves stay on the same side. This partial crossing allows visual information from the same visual field to be processed together in the opposite hemisphere of the brain.
223. Where do most fibers of the corticospinal tract decussate (i.e., cross over)?
- A. anterior horn of the spinal cord
- B. medullary pyramids
- C. internal capsule
- D. cerebral peduncles
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Correct answer: B
The corticospinal tract is a major pathway for carrying movement-related information from the brain to the spinal cord. Most corticospinal tract fibers decussate (i.e., cross over) at the level of the medullary pyramids in the lower brainstem, forming the lateral corticospinal tract.
224. In NMDA receptor-dependent long-term potentiation (LTP), activation of NMDA receptors leads to an increase in the number of which type of receptor at the postsynaptic membrane?
- A. GABA-A receptors
- B. NMDA receptors
- C. AMPA receptors
- D. dopamine receptors
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Correct answer: C
In NMDA receptor-dependent LTP, calcium influx through activated NMDA receptors initiates signaling cascades that promote the insertion of AMPA receptors into the postsynaptic membrane, enhancing synaptic strength.
225. Which structure is primarily responsible for secreting melatonin into the bloodstream in a circadian pattern to regulate the sleep–wake cycle?
- A. adrenal glands
- B. pituitary gland
- C. pineal gland
- D. hippocampus
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Correct answer: C
Although melatonin is produced in several parts of the body, the pineal gland is the main source of melatonin released into the bloodstream in a circadian pattern. It receives signals from the suprachiasmatic nucleus (SCN) of the hypothalamus and increases melatonin production in darkness, helping to regulate the sleep–wake cycle.
226. A physician shines a light into a patient's right eye, and neither the right nor the left pupil constricts. When light is shined into the patient's left eye, both pupils constrict. Which of the following structures is most likely damaged?
- A. right optic nerve
- B. right oculomotor nerve
- C. left optic nerve
- D. left oculomotor nerve
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Correct answer: A
The sensory limb of the pupillary light reflex is the optic nerve (CN II). If light shined into one eye fails to cause constriction in either eye, it suggests a problem with the sensory input—in this case, the right optic nerve. The motor (efferent) pathways are still intact, as the pupils can constrict when the other eye is stimulated.
227. Which of the following is the thinnest layer of the meninges?
- A. dura mater
- B. arachnoid mater
- C. pia mater
- D. falx cerebri
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Correct answer: C
The pia mater is the innermost and thinnest meningeal layer. It closely adheres to the surface of the brain and spinal cord. In contrast, the dura mater is the thickest and toughest layer, and the arachnoid mater is intermediate in thickness.
228. Which of the following is the primary treatment for Wernicke-Korsakoff syndrome?
- A. antipsychotic medication
- B. dopamine agonists
- C. selective serotonin reuptake inhibitors (SSRIs)
- D. thiamine (vitamin B1) supplementation
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Correct answer: D
Wernicke-Korsakoff syndrome is most often caused by a deficiency of thiamine (vitamin B1), commonly associated with chronic alcohol use. Treatment typically involves prompt administration of thiamine to prevent or limit further neurological damage.
229. Which of the following functions are the inferior olivary nuclei most closely associated with?
- A. Regulation of circadian rhythms
- B. Coordination and movement-related learning
- C. Control of emotional responses
- D. Maintenance of respiration
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Correct answer: B
The inferior olivary nuclei play a key role in motor learning and coordination. They send climbing fiber inputs to the cerebellum, helping it fine-tune movements and adapt based on sensory feedback. This pathway is especially important for learning new motor skills and correcting errors during movement.
230. When a neuron is at rest (i.e., not in the process of firing an action potential), where is the concentration of sodium ions highest?
- A. inside the cell
- B. outside the cell
- C. in the nucleus of the cell
- D. sodium ions are evenly distributed on both sides of the cell membrane
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Correct answer: B
At rest, a neuron maintains its resting membrane potential by keeping more sodium ions (Na⁺) outside the cell and more potassium ions (K⁺) inside. Thus, sodium concentration is much higher outside the neuron when it’s at rest.
231. Which of the following describes how functional magnetic resonance imaging (fMRI) works?
- A. Measures electrical signals from the scalp to record brain activity
- B. Uses radioactive tracers to measure thinks like metabolism, blood flow, etc.
- C. Detects changes in blood oxygen levels to identify active brain regions
- D. Uses X-rays to create images of brain structure
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Correct answer: C
fMRI works by detecting changes in blood oxygen levels—the BOLD (blood-oxygen-level-dependent) signal—which lets us see which brain regions are more active based on their oxygen use.
232. Spina bifida is a disorder that results from disrupted formation of which of the following structures during early embryonic development?
- A. meninges
- B. neural crest
- C. vertebral arch
- D. neural tube
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Correct answer: D
Spina bifida results from the incomplete closure or disruption in the formation of the neural tube during early embryonic development. The neural tube is the precursor to the brain and spinal cord, and when it fails to close properly, it can lead to defects such as spina bifida.
233. The sensory receptors (hair cells) of the semicircular canals are found in expansions of the semicircular canals called:
- A. utricles
- B. saccules
- C. ampullae
- D. cochlear ducts
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Correct answer: C
The ampullae of the semicircular canals contain hair cells that respond to rotational movements of the head. The utricle and saccule detect linear acceleration, and the cochlear duct is involved in hearing.
234. This gyrus contains the primary somatosensory cortex:
- A. precentral gyrus
- B. cingulate gyrus
- C. postcentral gyrus
- D. superior temporal gyrus
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Correct answer: C
The postcentral gyrus is located posterior to the central sulcus and contains the primary somatosensory cortex, which is responsible for processing touch, pressure, pain, temperature, and proprioceptive information from the body.
235. Whch of the following cranial nerves carries the majority of all the parasympathetic fibers in the body?
- A. Trigeminal nerve (CN V)
- B. Glossopharyngeal nerve (CN IX)
- C. Vagus nerve (CN X)
- D. Accessory nerve (CN XI)
Show Answer
Correct answer: C
The vagus nerve (cranial nerve X) carries over 75% of all parasympathetic fibers in the body. It innervates organs in the thorax and abdomen, including the heart, lungs, and digestive tract, making it the main parasympathetic nerve of the body.
236. When referring to the spinal cord, ventral means:
- A. Toward the back of the spinal cord
- B. Toward the front of the spinal cord
- C. Toward the brain
- D. Away from the midline
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Correct answer: B
Ventral refers to the front or belly side of the body. In the spinal cord, this means toward the front, where motor neurons exit to control muscles.
237. Which type of glial cell helps form the blood-brain barrier by extending end-feet that wrap around blood vessels in the brain?
- A. microglia
- B. astrocytes
- C. Schwann cells
- D. oligodendrocytes
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Correct answer: B
Astrocytes contribute to the blood-brain barrier by sending out processes (end-feet) that wrap around brain capillaries. These end-feet contribute to the formation and regulation of the blood-brain barrier.
238. Which division of the peripheral nervous system contains the most neurons?
- A. somatic nervous system
- B. sympathetic nervous system
- C. parasympathetic nervous system
- D. enteric nervous system
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Correct answer: D
The enteric nervous system is involved with the regulation of the gastrointestinal tract. It’s thought to contain somewhere between 400-600 million neurons, which would make it the largest and most complex division of the peripheral nervous system.
239. Repolarization during a neuron's action potential is primarily caused by which ion movement?
- A. Potassium (K⁺) moving out of the cell through voltage-gated channels
- B. Sodium (Na⁺) moving into the cell through voltage-gated channels
- C. Chloride (Cl⁻) moving out of the cell through ligand-gated channels
- D. Calcium (Ca²⁺) moving into the cell through voltage-gated channels
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Correct answer: A
The opening of voltage-gated K⁺ channels leads to K⁺ flowing out of the cell, driving the membrane potential back toward resting membrane potential.
240. Which of the following fibers carry information to the spinal cord about fast, sharp pain?
- A. C fibers
- B. A-beta fibers
- C. A-delta fibers
- D. D fibers
Show Answer
Correct answer: C
A-delta fibers are thinly myelinated and conduct signals relatively quickly, carrying information about fast, sharp, well-localized pain.
