PRE-CLINICAL
A study is done to identify the normal bacterial flora of the mouth. One bacterial species that was found to colonize the mouth is a gram-positive coccus that grows in chains and is catalase-negative. When it is grown on blood agar, alpha-hemolysis is noted. Additionally, this bacterium was tested for optochin sensitivity and was optochin-resistant. Which of the following is an additional feature of this bacterium?
A) It is urease positive
B) It is encapsulated
C) It is bile-insoluble
C) It is bile-insoluble
Major takeaway
Streptococcus viridans are Gram-positive streptococci that cause alpha-hemolysis in blood agar. They are optochin-resistant and bile-insoluble.
Scientists are studying human lung development. Which of the following best describes the gestation age at which the surfactant achieves mature levels?
A)25 weeks
B)35 weeks
C)20 weeks
B)35 weeks
Major takeaway
Surfactant synthesis begins at ~20 weeks’ gestation and achieves mature levels at ~35 weeks of gestation.
A 6-year-old boy is brought to the pediatrician for evaluation of problems at school. The patient started kindergarten three months ago. Recently, his teacher called his father to inform him that the patient does not speak during class or with classmates. During playtime, the patient chooses to play on his own and does not speak with other children. His father found this news surprising since the patient enjoys singing at home and is talkative with his siblings. The patient has met all developmental milestones and past medical history is unremarkable. Vitals are within normal limits. Physical examination is noncontributory. Which of the following is the most likely diagnosis?
A)Childhood-onset fluency disorder
B)Selective mutism
C)Language disorder
B)Selective mutism
Major takeaway
Selective mutism is a disorder in children that usually develops before the age of 5 which is characterized by a refusal to speak in specific social settings. It is highly comorbid with social anxiety disorder. Treatment may involve reducing social anxiety with cognitive behavioral therapy and selective serotonin reuptake inhibitors.
Pregnancy is defined by the National Institutes of Health, the American College of Obstetricians and Gynecologists, and the Food and Drug Administration as implantation of the blastocyst in the endometrium. Which of the following is the most common location for fertilization of the ovum?
A)Isthmus
B)Ampulla
C)Uterus
B)Ampulla
Major takeaway
Fertilization most commonly occurs in the ampulla, which is the widest section of the fallopian tubes.
A 24-year old man is brought to the emergency department by his partner for evaluation of visual hallucinations. The patient states he can see “fire moving through the air” and that sounds “appear brighter.” The patient tells the physician he believes he is “having a bad trip because of a drug he took.” He has no history of psychiatric illnesses. Temperature is 37.1 °C (98.8 °F), respirations are 15/minute, pulse is 92/minute, and blood pressure is 130/85 mmHg. The patient is oriented to place and time. Physical examination demonstrates mydriasis. Urine toxicology is negative. Which of the following substances is most likely responsible for this patient’s presentation?
A)Lysergic acid diethylamide
B)Marijuana
C)Cocaine
A)Lysergic acid diethylamide
Major takeaway
Lysergic acid diethylamide (LSD) intoxication typically results in patients experiencing varying degrees of visual hallucinations and euphoria. Patients are usually oriented and understand that what they are experiencing is due to the effects of the drug.
During a neurology lecture, students learn that the thalamus is the central relay station for all ascending sensory information, except for olfaction. Which of the following thalamic nuclei relays auditory information?
A) Medial geniculate nucleus
B) Ventral anterior and lateral nuclei
C)Ventral posteromedial nucleus
A) Medial geniculate nucleus
Major takeaway
The medial geniculate nucleus relays auditory information from the superior olive and inferior colliculus of the tectum to the primary auditory cortex.
A researcher is studying respiratory physiology. Which of the following conditions will most likely lead to an increase in lung compliance?
A)Guillain-Barre syndrome
B)Idiopathic pulmonary fibrosis
C)Emphysema
C)Emphysema
Major takeaway
Lung compliance measures the change in lung volume for a given change in pressure. A decrease in pulmonary elastic tissue will increase compliance. In contrast, increased pulmonary elastic tissue, increased alveolar filling, or decreased surfactant production will decrease compliance.
A 24-year-old gravida 2 para 1 woman comes to the obstetrician for evaluation of painful uterine contractions. The patient is in the 32nd week of gestation. She describes her contractions as regular and increasing in frequency. The patient has a history of preterm delivery in her previous pregnancy. She did not have any complications during this pregnancy. Examination reveals cervical dilation. The physician decides to administer terbutaline. Which of the following is a possible side effect of terbutaline?
A)Hyperglycemia
B)Hypoglycemia
C)Gastritis
A)Hyperglycemia
Major takeaway
Terbutaline is a tocolytic medication used to delay preterm labor. Side effects include tachycardia, arrhythmias, and hyperglycemia.
A 34-year-old woman, gravida 2 para 2, is brought to the office by her partner for evaluation of low energy and persistent fatigue. She recently gave birth via vaginal delivery three weeks ago; the prenatal period and birth were uneventful, and the neonate has been doing well. She is currently breastfeeding. The patient has been feeling hopeless for two weeks and states, “I don’t know if I can do this anymore.” She has had several episodes of crying “for no reason,” and she attributes it to feeling overwhelmed with her newborn. She sleeps 4-6 hours per day. She used to enjoy attending book club meetings with her friends, but she no longer has an interest in this activity. She has no suicidal or homicidal ideation and has not experienced visual hallucinations or hearing voices. The patient has a history of postpartum blues following her first pregnancy five years ago. She takes no medications. Vitals are within normal limits. Examination reveals a visibly tired woman. Which of the following is the most likely diagnosis?
A)Postpartum psychosis
B)Adjustment disorder with depressed mood
C)Postpartum depression
C)Postpartum depression
Major takeaway
Postpartum depression is diagnosed using the same diagnostic criteria for a major depressive episode and typically occurs within the first few months of parturition. Management consists of antidepressants and/or psychotherapy.
A 35-year-old man is brought to the emergency department by EMS after he was found at a public park yelling at bystanders. Several unlabeled pill capsules are found in his belongings. Temperature is 100°F (37.7 °C), pulse is 117 bpm, respiratory rate is 18 breaths per minute, and blood pressure is 177/90 mmHg. The patient appears agitated and diaphoretic. On physical examination, the patient has noted mydriasis bilaterally. There is absence of clonus in the lower extremities bilaterally. Oral mucosa appears moist. Intranasal examination reveals septal ulceration. Which of the following is the most likely etiology of this patient’s clinical presentation?
A)Cannabis intoxication
B)Amphetamine intoxication
C)Opiate withdrawal syndrome
B)Amphetamine intoxication
Major takeaway
Cocaine and amphetamines are psychostimulants that can produce similar clinical features including decreased sleep, reduced appetite, pupillary dilation, psychomotor agitation, hypertension, and tachycardia.
A patient’s arm is held in flexion, and a reflex hammer strikes the posterior aspect of the elbow, which causes a subsequent contraction in the triceps muscle. Which of the following nerve roots is/are being tested in the maneuver?
A)C7-C8
B)C5-C6
C)C4-C5
A)C7-C8
Major takeaway
The C7-C8 nerve roots create the triceps reflex arc. In contrast, the C5-C6 nerve roots create the biceps and brachioradialis reflex arcs.
A 45-year-old man comes to the clinic because of a recent weight loss of 4.5-kg (9.9-lb) and recurrent fatty stools over the past several months. The patient has a history of diabetes mellitus and gallstones. Laboratory studies show decreased concentrations of pepsinogen, amylase, lipase, insulin, and glucagon. A CT scan shows a mass in the pancreas. Based on this patient's symptoms, which of the following substances might be secreted by this pancreatic tumor?
A)Secretin
B)Somatostatin
C) Gastrin
B)Somatostatin
Major takeaway
Somatostatin is an inhibitory hormone that acts on multiple cells in the digestive system. Somatostatinomas are neuroendocrine tumors that occur in the pancreas and gastrointestinal tract. Characteristic features include weight loss, diabetes mellitus, gallstones, and steatorrhea.
An experiment is performed to determine the reactions of the eye to different environments. In the first part of the experiment, an individual is kept in a dark room for 2 hours. After 2 hours, the light in the room is turned on. Which of the following best describes the changes expected to be seen in this individual?
A)Increased parasympathetic stimulation of the dilator pupillae muscle, causing mydriasis
B)Increased sympathetic stimulation of the sphincter pupillae muscle, causing miosis
C)Increased parasympathetic stimulation of the sphincter pupillae muscle, causing miosis
Increased parasympathetic stimulation of the sphincter pupillae muscle, causing miosis
Major takeaway
When transitioning from a darker to brighter environment, the parasympathetic nervous system stimulates the sphincter pupillae muscle to cause miosis.
A 43-year-old man presents to an outpatient clinic for a routine visit. The patient was diagnosed with HIV infection 2 years ago. Current medications include emtricitabine, tenofovir, and dolutegravir. The patient is found to have persistently elevated HIV-1 levels despite being on highly active antiretroviral therapy. Enfuvirtide is added to the patient’s treatment regimen. Which of the following side effects is this patient at greatest risk of developing with this new medication?
A)Injection site reaction
B)Hyperglycemia
C)Bone marrow suppression
A)Injection site reaction
Major takeaway
Enfuvirtide is a viral entry inhibitor that binds to the viral gp41 protein. It is given to patients who show replication of HIV-1 despite ongoing antiretroviral therapy. Side effects include injection site reaction and an increased risk of bacterial infections.
A group of researchers are studying the metabolic effects of alcohol use disorder and the associated electrolyte abnormalities. Which of the following combinations is most likely to be present in an individual with severe alcohol use disorder?
A)Severe hypomagnesemia, increased PTH
B)Moderate hypomagnesemia, decreased PTH
C)Severe hypomagnesemia, decreased PTH
C)Severe hypomagnesemia, decreased PTH
Major takeaway
Alcohol use disorder would result in severe hypomagnesemia, leading to the inhibition of PTH release.
A patient with suspected appendicitis demonstrates maximal tenderness over the right lower abdomen, two-thirds of the distance from the umbilicus to the anterior superior iliac spine. This inflamed gastrointestinal lining originates from which of the following embryological layers?
A)Endoderm
B)Surface ectoderm
C)Mesoderm
C)Mesoderm
Major takeaway
The serous linings of body cavities (e.g., peritoneum, pericardium, pleura) are derived from mesoderm.
An autopsy is performed to determine the cause of sudden death in a 23-year-old athlete while playing baseball. The horizontal section of the heart at the level of the ventricles reveals asymmetric ventricular septal hypertrophy. If this patient had a pre-participation sports screening, cardiac auscultation would have likely revealed a murmur that increased with the following maneuvers?
A)Straining phase of Valsalva
B)Passive leg raising
C)Sustained handgrip
A)Straining phase of Valsalva
Major takeaway
Hypertrophic cardiomyopathy (HCM) can obstruct the left ventricular outflow tract (LVOT), which produces a harsh crescendo-decrescendo systolic ejection murmur that is best heard in the left lower sternal border. A decrease in preload (e.g. straining phase of Valsalva) or afterload increases the LVOT obstruction, increasing the intensity of the murmur.
A 34-year-old woman is brought to the emergency department by family members due to altered mental status and fever. The patient’s symptoms started abruptly 24 hours ago with high fever and malaise. She then began experiencing abdominal pain and nausea and vomited twice. Past medical history is notable for recent trauma and nose bleeding after being hit in the face by a football five days ago, which was treated with nasal packings inserted into the left nostril. The packing is still inside the patient’s nose. She occasionally uses acetaminophen for headaches. The patient broke up with her boyfriend a week ago. Temperature is 39.0°C (102.2°F), blood pressure is 88/60 mmHg, and pulse is 130/min. The patient is confused and unable to answer questions. Physical examination reveals a diffuse red macular rash. Liver enzymes are elevated, and platelet count is decreased. Which of the following is the most likely cause of this patient’s condition?
A)Suicide attempt via acetaminophen overdose
B)Membrane toxin found on the surface of colonizing bacteria that activates macrophages
C)Superantigen produced by colonizing bacteria that activates T-cells and macrophages
C)Superantigen produced by colonizing bacteria that activates T-cells and macrophages
Major takeaway
Staphylococcus aureus causes toxic shock syndrome by producing toxic-shock syndrome toxin, which results in massive activation of immune cells, cytokine storm, and eventually multi-organ failure.
A 34-year-old man presents to the emergency department with chest pain. The patient was insufflating a white powder earlier in the evening, and his symptoms developed shortly after that. Temperature is 37.2°C (99.0°F), pulse is 144/min, respirations are 22/min, blood pressure is 201/84 mmHg, and oxygen saturation is 99% on room air. Physical examination reveals diaphoresis and mydriasis. Which of the following medications is contraindicated, given this patient’s clinical presentation?
A)Lorazepam
B)Labetalol
C)Midazolam
B)Labetalol
Major takeaway
ꞵ-blockers are contraindicated in managing cocaine use due to the risk of unopposed α-stimulation.
A 47-year-old woman presents to the emergency department due to altered mental status. She is accompanied by her partner, who reports that the patient was in her usual state before having severe nausea and vomiting during dinner. Medical history is remarkable for long-standing Graves disease, but the patient has been non-compliant with medications. Last week, she had an upper respiratory infection that was resolved without treatment. Temperature is 40°C (104.0°F), pulse is 155/min and irregular, and blood pressure is 155/100 mmHg. On physical examination, the patient is agitated and in severe distress. The patient’s skin is moist, and a large goiter is noted. Laboratory tests show an elevated T3 and T4, low TSH, elevated liver enzymes, mild hyperglycemia, and leukocytosis. The patient is administered IV propranolol, propylthiouracil, and hydrocortisone. An hour later, the doctor adds a potassium iodide-iodine (Lugol's) solution to the treatment. This medication has which of the following immediate effects?
A)Inhibition of the conversion of T4 to T3
B)Inhibition of hormone release
C)Inhibition of iodide uptake into thyroid follicular cells
B)Inhibition of hormone release
Major takeaway
Thyroid storm is a life-threatening condition characterized by overt thyrotoxicosis in the setting of longstanding untreated/undertreated hyperthyroidism. Treatment includes beta-blockers, antithyroid drugs, iodine solution, and glucocorticoids. Iodine solution inhibits the organification of iodide and hormone biosynthesis, a phenomenon known as the Wolff-Chaikoff effect. It also inhibits the release of thyroid hormones in the acute setting.
A 35-year-old woman presents to the clinic to establish care. She has not seen a doctor in many years. She has no active complaints. Physical examination is unremarkable. Cardiac auscultation reveals a midsystolic click followed by a short late-systolic murmur at the cardiac apex. When the patient is asked to bear down against a closed glottis, it makes the click occur earlier in systole. Which of the following is the most likely cause of change in the timing of systolic click with this maneuver?
A)Decrease in transaortic valve pressure gradient
B)Decrease in left ventricular volume
C)Increased right ventricular filling and ejection time
B)Decrease in left ventricular volume
Major takeaway
Mitral valve prolapse is characterized by a midsystolic click followed by a short late-systolic murmur. Maneuvers that change the LV end-diastolic volume affect the timing of the click. Decreases in LV volume (e.g. secondary to decreased preload during the straining phase of Valsalva) causes the click to occur earlier.
A 6-day-old female is brought to the pediatrician by her parents for evaluation of jaundice. She was born at 36 weeks gestation to a 29-year-old, gravida 1 para 1, woman via an uncomplicated vaginal delivery. According to her parents, the patient has had difficulty latching to her mother’s breast. The patient has passed meconium and produces 3-4 wet diapers per day. In the office, she is fussy but consolable. Physical examination shows depressed anterior and posterior fontanelles. Scleral icterus and jaundice of the head and chest are observed. Cardiac, pulmonary, and abdominal exams are noncontributory. Which of the following best describes the pathophysiology of this patient’s condition?
A)Impaired conjugation of bilirubin in the liver
B)Decreased elimination of bilirubin via feces
C)Increased intestinal deconjugation of bilirubin
B)Decreased elimination of bilirubin via feces
Major takeaway
Breastfeeding failure jaundice causes unconjugated hyperbilirubinemia secondary due to decreased elimination of bilirubin via feces. The condition can cause jaundice, scleral icterus, and kernicterus. Patients will also have signs of dehydration, such as sunken fontanelles and reduced urine output. Treatment involves ensuring hydration and increasing the frequency and duration of feeds.
A 36-year-old man presents to the emergency department due to difficulty ambulation for the past four days. The patient reports “stumbling” and states, “I feel like my legs are getting weaker and weaker.” The patient has no other medical history and takes no medications daily. Vitals are within normal limits. Neurologic exam is notable for 3/5 strength in the lower extremities bilaterally and a decreased patellar and Achilles reflex bilaterally. The remainder of the neurologic examination is unremarkable. This patient’s condition was most likely preceded by infection with which of the following organisms?
A)Heliobacter pylori
B)Hepatitis C virus
C)Campylobacter jejuni
C)Campylobacter jejuni
Major takeaway
Previous Campylobacter jejuni infection has been associated with the subsequent development of Guillain-Barré syndrome and reactive arthritis. Guillain-Barré syndrome, oracute inflammatory demyelinating polyneuropathy, is an autoimmune condition that results from demyelination of Schwann cells in the peripheral nervous system. This condition typically manifests with ascending, bilateral weakness of the lower extremities.
A 34-year-old woman comes to the office to be evaluated for recurrent episodes of epigastric bloating and crampy pain. The pain usually begins after eating and is relieved by vomiting or lying on her stomach. The patient is a dancer and joined a training program a few months ago. She has lost 30-lbs (13.6 kg) over the past two months while on a “crash diet.” Past medical history is noncontributory. Temperature is 36.7°C (98°F), pulse is 100/min, respirations are 18/min, and blood pressure is 135/75 mmHg. Physical examination shows a mildly distended and tender abdomen with high-pitched bowel sounds. A plain abdominal x-ray reveals findings suggestive of proximal small bowel obstruction. The upper gastrointestinal series demonstrates a marked delay in the passage of the contrast from the duodenum into the more distal small bowel. The delay resolves when the patient takes a knee-chest position. Which of the following is the most likely cause of this patient’s condition?
A)Transmural inflammation of the intestine
B)Selective hypersensitization of visceral afferent nerves
C)Duodenal compression between arteries
C)Duodenal compression between arteries
Major takeaway
Superior mesenteric artery (SMA) syndrome occurs when the transverse portion of the duodenum is entrapped between the SMA and aorta, causing symptoms of bowel obstruction. It may present acutely with signs and symptoms of small bowel obstruction or chronically with recurrent episodes of abdominal pain, vague abdominal symptoms, and early satiety. It results from a decreased angle between the aorta and SMA, secondary to mesenteric fat loss, pronounced lordosis, or after surgical correction of scoliosis.
A 45-year-old woman comes to the emergency department after experiencing several episodes of non-bilious and non-bloody emesis, followed by a sudden onset of intense chest pain radiating to the back. She also notes that she has left arm weakness. The patient states that prior to today, she has been in her usual state of health. She drinks a pint of vodka daily and regularly uses intranasal cocaine. She reports last using cocaine this morning. Her temperature is 37.0 °C (98.6 °F), pulse is 102/min, respirations are 22/min, blood pressure is 210/120 mmHg, and oxygen saturation is 96% on room air. The patient appears disheveled and in significant distress. Physical examination shows 1+ peripheral pulses in the right upper extremity and 2+ pulses in the left upper extremity. Neurological examination shows 3/5 power in the left upper and lower extremities compared to 5/5 power in the right upper and lower extremities. Laboratory markers demonstrate a troponin of 0.7 ng/ml and a WBC of 12,000/mm3. ECG demonstrates ST-depressions in leads II, III, and aVF. Which of the following is the most likely underlying mechanism of this patient’s condition?
A)Atherosclerotic rupture of a right coronary artery plaque
B)Longitudinal cleavage of the aortic media
C)Aneurysmal rupture of the left middle cerebral artery
B)Longitudinal cleavage of the aortic media
Major takeaway
Aortic dissection is a potentially devastating vascular condition caused by longitudinal cleavage of the aortic tunica media created by a dissecting column of blood. The primary risk factor is uncontrolled hypertension and patients typically present with sudden onset sharp or tearing chest pain radiating to the back.