a. Point A

b. Point B

c. Point C

d. Point D

e. Point E

81. An 82-year-old woman with end-stage renal disease is brought to the emergency department complaining of nausea, vomiting, muscle cramps, and generalized weakness. Laboratory analysis reveals significant hyper-kalemia. Elevations of extracellular potassium ion concentration will have which of the following effects on nerve membranes?

a. The activity of the Na⁺–K⁺ pump will decrease

b. The membrane potential will become more negative

c. The membrane will become more excitable

d. Potassium conductance will increase

e. Sodium conductance will increase

82. A 16-year-old adolescent boy is brought to the emergency room by ambulance after suffering a concussion during a football game. When he awoke, he was able to understand and follow commands, including repeating language spoken to him, but he had difficulty with spelling, mild word-finding difficulty, and difficulty understanding written language and pictures. His condition is most likely caused by damage to which of the following?

a. Angular gyrus in the categorical hemisphere

b. Arcuate fasciculus connecting Broca and Wernicke areas

c. Broca area in the frontal lobe

d. Hippocampus

e. Wernicke area at the posterior end of the superior temporal gyrus

83. A 13-year-old adolescent boy has no movement in his legs after falling out of a tree. Neurological examination shows the absence of both the myotatic (stretch) and reverse myotatic reflexes in the lower extremities. Which of the following is the most important role of the γ-motoneurons?

a. Detect the length of resting skeletal muscle

b. Generate activity in Ib afferent fibers

c. Maintain Ia afferent activity during contraction of muscle

d. Prevent muscles from producing too much force

e. Stimulate skeletal muscle fibers to contract

84. A 72-year-old man visits his physician because he finds it difficult to hold his hand steady when painting. Examination reveals a resting tremor and rigidity. The symptoms are relieved by a single dose of levodopa. This patient’s neurological signs are most likely related to a lesion within which of the following?

a. Caudate nucleus and putamen

b. Cerebellum

c. Hippocampus

d. Premotor area

e. Substantia nigra

85. A 53-year-old man develops loss of pain and temperature sensation in his right leg and loss of proprioception in his left leg (Brown-Séquard syndrome). These symptoms appear 6 weeks following total prostatectomy for prostate cancer. A bone CT scan reveals metastases compressing the patient’s left hemicord. His urologist refers him to a neurologist who wishes to confirm normal proprioception in the left leg. Which figure below illustrates the train of action potentials normally seen in a sensory nerve encoding the velocity of limb movement in response to sudden movement?

a. A

b. B

c. C

d. D

e. E

86. A 72-year-old man develops selective loss of the large pyramidal cells in the precentral gyrus and degeneration of the corticospinal and corticobulbar projections. Other neuronal systems are spared. He is told that the progression of the disease is variable, and that the worst prognosis is about a 3-year survival. The precentral gyrus and corticospinal and corticobulbar tracts are essential for which of the following?

a. Auditory identification

b. Kinesthesia

c. Olfaction

d. Vision

e. Voluntary movement

87. A 62-year-old woman with a history of multiple head injuries in the past becomes progressively more confused, and develops urinary incontinence and a gait disorder. An MRI of the brain (shown below) and lumbar puncture are performed. Intracranial pressure is found to be within normal limits. The patient’s symptoms improved after ventriculoperitoneal shunting. Under normal conditions, which of the following statements correctly describes the cerebrospinal fluid (CSF)?

a. It is absorbed into the choroid plexus

b. It circulates in the epidural space

c. It has a higher protein concentration than plasma

d. It has a lower glucose concentration than plasma

e. Its absorption is independent of CSF pressure

88. A 78-year-old man is evaluated by a physiatrist after a stroke. The patient is observed to suffer from dysmetria, ataxia, and an intention tremor. These neurological signs are most likely related to a lesion within which of the following regions of the brain?

a. Basal ganglia

b. Cerebellum

c. Cortical motor strip

d. Eighth cranial nerve

e. Medulla

89. A 41-year-old man is seen by his physician complaining of “always feeling tired” and having “vivid dreams when he is sleeping.” He is referred to the hospital’s sleep center for evaluation. He is diagnosed with narcolepsy based on his clinical history and the presence of rapid eye movements (REM) as soon as he falls asleep. Which of the following signs will be observed when the patient is exhibiting REM sleep?

a. High-amplitude electroencephalogram (EEG) waves

b. Hyperventilation

c. Low frequency EEG waves

d. Periods of loss of skeletal muscle tone

e. Slow but steady heart rate

90. A 43-year-old woman has a chief complaint of muscle weakness. The distribution of muscle weakness and the presence of hyperactive tendon reflexes is consistent with pyramidal tract disease. Tapping the patella tendon elicits a reflex contraction of the quadriceps muscle. Which of the following occurs during the contraction of the quadriceps muscle?

a. The α-motoneurons innervating the extrafusal muscle fibers decrease their rate of firing

b. The α-motoneurons to the antagonistic muscles increase their rate of firing

c. The γ-motoneurons innervating the intrafusal muscle fibers increase their rate of firing

d. The Ia afferents from the muscle spindle increase their rate of firing

e. The Ib afferents from the Golgi tendon organ increase their rate of firing

91. A 64-year-old female patient is referred to a neurologist because her sister and brother both suffered recent strokes. She is diagnosed with an antiphospholipid antibody syndrome, and placed on warfarin. Despite the anticoagulation therapy, she develops a thrombotic cerebral infarct, which leads to spasticity of her left wrist, elbow, and knee. The infarction most likely affected which of the following?

a. Ia afferent fibers

b. Corticoreticular fibers

c. Corticospinal fibers

d. Reticulospinal fibers

e. Vestibulospinal fibers

92. A 27-year-old patient with a chief complaint of mild vertigo of 3-month duration is seen by a neurologist. Examination reveals a positional (horizontal and vertical) nystagmus that is bidirectional. The patient reports the absence of tinnitus. Which of the following is the most likely etiology of the vertigo?

a. Labyrinthitis

b. Lesion of the flocculonodular lobe of the cerebellum

c. Lesion of the spinocerebellum

d. Ménière syndrome

e. Psychogenic

93. A 16-year-old adolescent girl with epilepsy has an EEG recording done during a routine visit to her neurologist. The α-rhythm appearing on an EEG has which of the following characteristics?

a. It disappears when a patient’s eyes open

b. It is associated with deep sleep

c. It is replaced by slower, larger waves during REM sleep

d. It produces 20 to 30 waves per second

e. It represents activity that is most pronounced in the frontal region of the brain

94. A 29-year-old woman presents at the ophthalmologist’s office complaining of slowly progressive loss of vision. Based on the visual field defect shown here, the ophthalmologist determines that the patient has a right-sided homonymous hemianopia. She refers the patient to a neurologist who orders a CT scan of the head. The CT scan demonstrates a high-density, space-occupying lesion, which is compressing which area of the brain?

a. Left optic nerve

b. Left optic tract

c. Optic chiasm

d. Right lateral geniculate nucleus

e. Right visual cortex

For Questions 95 and 96

An 84-year-old woman presents to her cardiologist’s office complaining of hemiparesis that has worsened over the past 3 days. She is on anticoagulant therapy for atrial fibrillation. A noncontrast CT of the brain is shown below.

95. The CT findings reveal:

a. Amyloid angiopathy

b. Cerebral edema

c. Cerebral infarction

d. Subarachnoid hemorrhage

e. Subdural hematoma

96. On physical examination, stroking the plantar surface of her foot produces a reflex extension of the large toe rather than the expected flexion, which indicates damage to which of the following?

a. Basal ganglia

b. Brain stem

c. Cerebellum

d. Lower motoneurons

e. Upper motoneurons

97. A 59-year-old woman with an inherited neurodegenerative disease is admitted to the hospital because of agitation and aggression. Three years prior to admission, her irregular, flinging movements had become so severe that she could not walk or assist in her own care. Within which of the following areas of the brain the neuronal degeneration results in this presentation?

a. Anterior cerebellum

b. Limbic system

c. Striatum

d. Substantia nigra

e. Subthalamus

98. A 22-year-old woman presents at the student medical center with tachycardia and palpitations. She reports that she has been taking a diet supplement containing ephedrine that she purchased from an Internet site. Activation of the sympathetic nervous system by ephedrine causes smooth muscle contraction in which of the following?

a. Arterioles

b. Bronchioles

c. Ciliary bodies

d. Intestines

e. Pupils

99. A 27-year-old musician visits an otolaryngologist complaining of ringing in his ear. An audiometry test reveals a high-frequency hearing loss in which the threshold for hearing high-frequency sounds is raised by 1000 times. If a patient is unable to hear high-frequency sounds, the damage to the basilar membrane is closest to which of the following structures?

a. Helicotrema

b. Modiolus

c. Oval window

d. Spiral ganglion

e. Stria vascularis

100. An 86-year-old woman develops unilateral vesicular eruption on the trunk in a T₈ dermatomal pattern. Staining of the skin scrapings confirms a diagnosis of herpes zoster. The woman complains of significant pain, as well as increased sensitivity to touch. Which of the following receptors is responsible for measuring the intensity of a steady pressure on the skin surface?

a. Krause ending

b. Meissner corpuscle

c. Merkel disk

d. Pacinian corpuscle

e. Ruffini ending

101. A 41-year-old man complains to his physician about jet lag whenever he flies long distances to meetings. Melatonin is prescribed as a way to reset his circadian rhythm. The circadian rhythm is controlled by which of the following nuclei?

a. Arcuate

b. Lateral

c. Paraventricular

d. Suprachiasmatic

e. Ventromedial

102. A 48-year-old woman with multiple sclerosis (MS) and increasing spasticity is treated with an intrathecal infusion of baclofen, a GABA_B agonist that mediates presynaptic inhibition. Presynaptic inhibition in the central nervous system (CNS) affects the firing rate of α-motoneurons by which of the following mechanisms?

a. Decreasing the frequency of action potentials by the presynaptic nerve ending

b. Decreasing the potassium permeability of the α-motoneuron

c. Hyperpolarizing the membrane potential of the α-motoneuron

d. Increasing the amount of the neurotransmitter released by the presynaptic nerve ending

e. Increasing the chloride permeability of the presynaptic nerve ending

103. A 62-year-old woman is referred to a neurologist by her family physician because of a recent loss of initiative, lethargy, memory problems, and a loss of vision. She is diagnosed with primary hypothyroidism and an enlarged pituitary gland. She is referred to an endocrinologist for treatment of her thyroid problem and to a neuro-ophthalmologist for visual field evaluation. Which of the following visual field defects is most likely to be found?

a. A

b. B

c. C

d. D

e. E

104. A 24-year-old man complains of fatigue, increased daytime somnolence, and periodic sudden loss of muscle tone. Polysomnography confirms the diagnosis of narcolepsy. Narcolepsy is associated with which of the following?

a. Decreased adenosine levels in the reticular formation

b. Hypothalamic dysfunction with decreased CSF levels of orexins

c. Increased discharge of noradrenergic neurons in the locus ceruleus

d. Increased discharge of serotonergic neurons in the midbrain Raphé

e. The presence of prions

105. A 17-year-old boy is admitted to the hospital with a traumatic brain injury, sustained when he fell off his motorcycle. He develops a fever of 102.2°F (39°C), which is unrelated to an infection or inflammation. The fever is most likely due to a lesion of which of the following?

a. Anterior hypothalamus

b. Arcuate nucleus

c. Lateral hypothalamus

d. Paraventricular nucleus

e. Posterior nucleus

106. A medical student is working in a sensory physiology laboratory during the summer after her first year. She is responsible for conducting electrophysiologic recordings from several types of sensory receptor cells. The intracellular recordings shown in the figure below were obtained from receptor cells in response to a specific stimulus. From which of the following sensory receptors were these recordings obtained?

a. Auditory receptors

b. Photoreceptors

c. Smell receptors

d. Taste receptors

e. Touch receptors

107. A 34-year-old woman, who has been immobilized with a sprained ankle for the past 4 days, develops a throbbing pain that has spread to her entire left leg. History reveals that she has been taking oral contraceptives for 15 years. Ischemic pain is associated with which of the following?

a. A beta (Aβ) sensory fibers

b. Afferent pathway in the neospinothalamic tract

c. Overstimulation of somatic touch receptors

d. Rapidly adapting receptors

e. Sensory fibers terminating within the substantia gelatinosa of the dorsal horn of the spinal cord

108. A 42-year-old man sees his ophthalmologist because it is becoming increasingly difficult for him to read the newspaper. His vision problem most likely results from an inability to contract which of the following?

a. Ciliary body

b. Extraocular muscles

c. Iris

d. Pupils

e. Suspensory ligaments

109. At a first-grade parent–teacher conference, the teacher of a 6-year-old boy indicates that the boy seems to have difficulty hearing. His parents take him to the pediatrician, who refers the boy to an otolaryngologist. The boy is found to have a significant hearing deficit accompanying a middle ear infection that also involves the middle ear bones. Which of the following is the primary function of the middle ear bones?

a. Amplifying sounds

b. Enhancing frequency discrimination

c. Filtering high-frequency sounds

d. Localizing sound

e. Protecting the ear from load sounds

110. The morning after a rock concert, a 20-year-old college student notices difficulty hearing his professor during lecture. The physician at the student health center suspects possible damage to his hair cells by the loud music. Depolarization of the hair cells in the cochlea is caused primarily by the flow of which of the following?

a. Ca²⁺ into the hair cell

b. Cl⁻ out of the hair cell

c. K⁺ into the hair cell

d. K⁺ out of the hair cell

e. Na⁺ into the hair cell

111. A 62-year-old man with a history of hypertension and hyperlipidemia is admitted to the hospital for evaluation after demonstrating signs and symptoms of a stroke. Subsequent CT scans, perceptual tests, and a neurological examination provide evidence for impairment of the otolith pathways. The otolith organs (utricle and saccule) are responsible for which of the following?

a. Detecting angular acceleration

b. Detecting the position of the head in space

c. Producing rotary nystagmus

d. Producing the stretch reflex

e. Producing the vestibulo-ocular reflex

112. A 27-year-old man with severe epilepsy, characterized by major convulsions and lapses of consciousness every few minutes, underwent experimental neurosurgery to help relieve his seizures. The operation had a significant, beneficial effect on the epilepsy, but led to a devastating memory deficit. He had normal procedural memory, maintained long-term memory for events that occurred prior to surgery, and his short-term memory was intact, but he could not commit new events to long-term memory (loss of declarative memory). Which of the following areas of the brain was bilaterally resected in this patient?

a. Cerebral cortex

b. Cingulate gyrus

c. Hypothalamus

d. Parietal lobe

e. Temporal lobe

113. A 68-year-old man with avitaminosis A presents with a chief complaint of night blindness (nyctalopia). Which of the following reactions in the retinal rods is caused directly by the absorption of light energy?

a. Decomposition of scotopsin

b. Dissociation of scotopsin and metarhodopsin

c. Transformation of 11-cis retinal to all-trans retinal

d. Transformation of metarhodopsin to lumirhodopsin

e. Transformation of vitamin A to retinene

114. A 20-year-old boxer presents at a neurologist’s office complaining of dizziness and a problem with his balance. He indicates that in a recent match, he suffered several blows to the ears. Which of the following normally happens when a person slowly rotates toward the right?

a. Both the left and right eyes deviate toward the left

b. The endolymph in the left and right horizontal semicircular canals moves in opposite directions

c. The hair cells in the left horizontal semicircular canal become depolarized

d. The stereocilia on the hair cells in the right horizontal semicircular canal bend away from the kinocilium

e. The visual image on the retina becomes unfocused

115. A 58-year-old woman goes to her physician because she is having difficulty threading needles. An eye examination leads to the diagnosis of presbyopia (old eyes). Her condition is most likely caused by which of the following?

a. Ciliary muscle paralysis

b. Clouding of the vitreous

c. Degeneration of the macula

d. Retinal detachment

e. Stiffening of the lens

116. An 8-year-old boy is hit in the head by a baseline drive during a little league game. His father, a doctor, rushes out on the field to do a neurological assessment, including use of his penlight to check reactivity of the pupils. When light strikes the eye, which of the following normally increases?

a. The activity of transducin

b. The amount of transmitter released from the photoreceptors

c. The concentration of all-trans retinal within the photoreceptors

d. The concentration of calcium within the photoreceptors

e. The activity of guanylyl cyclase

117. A 59-year-old woman with bilateral glaucoma is treated with drops of the parasympathetic agent pilocarpine. Cholinergic stimulation of the pupil causes which of the following?

a. Absence of the pupillary response to light

b. Inequality of pupil size

c. Pupillary constriction (miosis)

d. Pupillary dilation (mydriasis)

e. Tonic pupil (slow redilation after exposure to light)

118. A 20-year-old woman complains of altered taste following extraction of her wisdom teeth. Which of the following is the most likely cause of the dysgeusia?

a. A disturbed salivary milieu

b. Damage to the central gustatory pathways

c. Damage to the gustatory afferent nerves

d. Impaired transport of the tastant to the receptor cells in the taste bud

e. Injury to the taste receptor cells

119. A 52-year-old man has a motor vehicle accident and closed head injury, after which he notes decreased sense of smell. Anosmia after head injury is most likely associated with which of the following?

a. Direct injury to the olfactory bulbs

b. Fractures of the cribriform plate

c. Low Glasgow coma scale

d. Recovery of olfaction over time to baseline

e. Shearing of the olfactory fila as they pass through the cribriform plate

120. A Jewish couple present at the pediatrician’s office with concerns about their 6-month-old child. They report that the infant was perfectly fine for the first few months of life, but lately he is very easily startled by noise, he has difficulty swallowing, he can no longer hold his head up, and he had a seizure earlier in the day. On physical examination, the doctor also notes “cherry-red” spots in the child’s eyes. These symptoms are due to the accumulation of harmful quantities of which of the following substances in the brain?

a. Beta-amyloid

b. Beta-hexosaminidase A

c. Ganglioside GM2

d. Sphingomyelin

e. Tau protein

121. A 24-year-old male medical student develops apprehension, restlessness, tachycardia, and tachypnea as he enters the testing center for his initial licensure examination. Activation of which of the following receptors would be expected to decrease his anxiety?

a. GABA_A

b. Glutamate

c. Histamine

d. Neurokinin 1 (NK-1, substance P)

e. Neuropeptide Y

122. A 26-year-old African American female medical student goes to the emergency department when she sees flashes of light, moving spots, and has reduced visual acuity. An ophthalmology consult reveals that she is myopic, does not have eye pain, and has a scotoma in the peripheral vision field of her right eye. There is no cherry red spot on the fovea. Which of the following is the most likely cause for her acute vision loss?

a. Central retinal artery embolism

b. Glaucoma

c. Macular degeneration

d. Optic neuritis

e. Retinal detachment

123. After sitting with one leg crossed under the other for several hours while working on a document at her computer terminal, a 52-year-old woman tries to stand up, but is unable to walk on the crossed leg, and feels tingling and pain. Which of the following explains the loss of motor function without the loss of pain sensation in the peripheral nerves?

a. A fibers are more susceptible to local anesthetics than C fibers

b. Aβ fibers are more sensitive to pressure than C fibers

c. C fibers are more sensitive to pressure than Aβ fibers

d. C fibers are more susceptible to hypoxia than B fibers

e. C fibers have higher conduction velocities than A fibers

124. Three weeks following a gastrointestinal (GI) infection with Campylobacter jejuni, a 60-year-old man develops weakness and tingling in his legs. Over the next few days, his legs and face become paralyzed, and he is hospitalized for Guillain–Barré syndrome (GBS). Which of the following is the most likely underlying cause of his motor paralysis?

a. Antibodies against nerve growth factor

b. Antibodies against oligodendrogliocytes

c. Demyelination of Aβ fibers

d. Demyelination of B fibers

e. Demyelination of C fibers

125. A 32-year-old woman from the IT department presents to the employee health clinic late in the afternoon complaining of fatigue, muscular weakness, and double vision. She indicates that the symptoms have been getting worse over the past 2 months and that she gets worse the longer she works at the computer screen. Cranial nerve examination discloses impaired movement of the right eye and bilateral ptosis, which worsen with repetitive eye movements. An MRI of the chest shows enlargement of the thymus gland. The neuropathy of this clinical presentation is most likely caused by antibodies against which of the following?

a. Acetylcholine

b. Acetylcholinesterase

c. Postsynaptic muscarinic acetylcholine receptors

d. Presynaptic nicotinic acetylcholine receptors in autonomic ganglia

e. Postsynaptic nicotinic acetylcholine receptors on the motor end plate

126. A 26-year-old woman presents with unilateral facial weakness. She states that whenever she tries to close her eyes, the upper eyelid on the affected side rolls upward. Electromyography on the affected side shows evidence of axonal degeneration. Which of the following characteristics of an axon is most dependent on its diameter?

a. The magnitude of its resting potential

b. The duration of its refractory period

c. The conduction velocity of its action potential

d. The overshoot of its action potential

e. The activity of its sodium–potassium pump

127. An 80-year-old farmer presented with complaints of weakness and fatigue, aching, orthostatic hypotension, constipation, and sleep disturbances. His family physician told him that he was just getting old, and would have to get used to it. His bradykinesia worsened and he couldn’t pick up his feet when he walked. When he was no longer able to plow his own fields, he got depressed, and his wife said he would just sit at the table and rub his thumb along his fingers. She called her son-in-law, a neurologist, and asked him if he’d come out to the country to evaluate “Pops.” The pathophysiology of Parkinson disease can be attributed to a paucity of which of the following neurotransmitters?

a. Acetylcholine

b. Dopamine

c. Glutamate

d. Neuropeptide Y

e. Serotonin

128. A 62-year-old man with COPD presents to the emergency room in respiratory distress. The attending physician uses succinylcholine to produce skeletal muscle relaxation prior to tracheal intubation. Soon after infusion of the succinylcholine, the patient develops a severe bradycardia. Which of the following drugs would counteract the bradycardia without affecting muscle relaxation?

a. Acetylcholine

b. Atropine

c. Curare

d. Dopamine

e. Epinephrine

129. A fireman suffers extensive burns, resulting in a fluid and electrolyte imbalance. Which of the following electrolyte imbalances will produce a decrease in the magnitude of a nerve membrane action potential?

a. Hyperkalemia

b. Hypernatremia

c. Hypocalcemia

d. Hypokalemia

e. Hyponatremia

130. A 19-year-old woman with a history of diplopia and paresthesia is diagnosed with MS. Immersion of an affected limb in a cold bath restores nerve conduction in many MS patients. The explanation often cited for this effect is that cold increases the duration of the action potential. Which of the following best explains why increasing the duration of the action potential can restore nerve conduction in patients with MS?

a. The amount of sodium entering the nerve with each action potential increases

b. The capacitance of the nerve fiber membrane is increased

c. The duration of the refractory period is increased

d. The potassium conductance of the membrane is increased

e. The membrane potential becomes more positive

131. A 37-year-old woman presents with severe migraine headaches that are accompanied by hemiparalysis. Genetic analysis confirms the suspicion of an inherited channelopathy. The membrane potential will depolarize by the greatest amount if the membrane permeability increases for which of the following ions?

a. Chloride

b. Potassium

c. Sodium

d. Chloride and potassium

e. Sodium and potassium

132. A 65-year-old postgastrectomy patient presents to his gastroenterologist’s office with fatigue, weakness in his legs, and frequent falls over the past several months. His physical examination demonstrates increased deep tendon reflexes and decreased vibratory sense in his toes. Laboratory analysis reveals megaloblastic anemia and vitamin B₁₂ deficiency. Which of the following mechanisms cause the neurological deficits characteristic of vitamin B₁₂ deficiency?

a. Decreased folate concentration

b. Decreased myelin synthesis

c. Decreased Na⁺–K⁺ pump activity

d. Increased hyperphosphorylated microtubule protein tau

e. Production of antinerve antibodies (ANA)

133. A 52-year-old man presents at the oral surgeon’s office with an abscessed tooth. Prior to surgery to extract the tooth, the patient is given a shot of procaine. Preventing the inactivation of sodium channels by local anesthetics will decrease which of the following?

a. Downstroke velocity of nerve cell action potentials

b. Duration of nerve cell action potentials

c. Magnitude of the overshoot in nerve cell action potentials

d. Relative refractory period of nerve cells

e. Upstroke velocity of nerve cell action potentials

134. A 13-year-old boy on the junior high wrestling team experienced attacks of proximal muscle weakness that lasted from 30 minutes to as long as 4 hours following exercise and fasting. The trainer attributed it to the symptoms of fatigue, but his mother recalled having similar symptoms when she was on a diet and exercise regime. Genetic testing revealed an inherited channelopathy. Electrically excitable gates are normally involved in which of the following?

a. Depolarization of the end-plate membrane by acetylcholine

b. Hyperpolarization of rods by light

c. Increase in nerve cell potassium conductance caused by membrane depolarization

d. Release of calcium from ventricular muscle sarcoplasmic reticulum

e. Transport of glucose into cells by a sodium-dependent, secondary active transport system

135. A 58-year-old man with a history of hypertension and renal disease presents at his physician’s office with a complaint of headaches. His blood pressure is 190/115 mm Hg and laboratory results show an elevated plasma renin activity with hypernatremia. Which of the following best describes the sodium gradient across the nerve cell membrane?

a. It is a result of the Donnan equilibrium

b. It is maintained by a Na⁺/Ca²⁺ exchanger

c. It is significantly changed during an action potential

d. It is the primary determinant of the resting membrane potential

e. It is used as a source of energy for the transport of other ions

136. A 19-year-old sexually active woman presents with lower abdominal pain for 1 week. Physical examination reveals a temperature of 101°F (38.33°C), tenderness on pelvic examination, and a mucopurulent vaginal discharge. Synaptic transmission between pain fibers from the pelvis and spinal cord neurons is mediated by which of the following?

a. Acetylcholine

b. Endorphins

c. Serotonin

d. Somatostatin

e. Substance P

137. A 16-year-old, highly allergic girl who is stung by a bee gives herself a shot of epinephrine prescribed by her physician. Because epinephrine activates β-adrenergic receptors, it will relieve the effects of the bee sting by decreasing which of the following?

a. Contraction of airway smooth muscle

b. Rate of depolarization in the SA node

c. Rate of glycogenolysis in the liver

d. Strength of ventricular muscle contraction

e. Transport of calcium into skeletal muscle fibers

138. A 10-year-old girl with type I diabetes develops a neuropathy of sensory neurons with free nerve endings. As a result, quantitative sensory testing will reveal higher-than-normal thresholds for detection of which of the following stimuli?

a. Fine touch

b. Muscle length

c. Pressure

d. Temperature

e. Vibration

139. An 85-year-old man is brought to his doctor by his daughter. She reports that he has memory loss, is often confused, and has been having increasing difficulty with routine activities that he used to do on his own, such as paying bills and going grocery shopping. She wonders if this is just because of old age or a more serious problem. Which of the following would provide the definitive diagnosis of Alzheimer disease?

a. Cerebral cortical atrophy on CT or MRI

b. Improved symptoms with cholinesterase inhibitors

c. Neuritic plaques containing A-beta (Aβ) amyloid bodies

d. Nonspecific slowing of the EEG

e. Presence of an apolipoprotein ε4 allele on chromosome 19

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