USMLE Step 1 Medical Subject Review: Physiology

You see a 55-year-old, Caucasian woman in your family practice, who complains about chest pain. The nurse had already taken the vitals and states that the patient is tachycardic. Which heart rate do you expect?

100-120/min, regular beat

An patient with acute pyelonephritis commonly exhibits tenderness upon gentle fist percussion of the back region overlying the inflamed kidney. The gentle fist percussion is applied immediately lateral to the vertebral column at what level?

12th thoracic vertebra

15-year-old girl visits an obstetrician/gynecologist. She has yet to begin menstruating and has not developed secondary sexual characteristics. She also suffers from frequent headaches. Her blood pressure is elevated; she is hypokalemic and hypernatremic. What is the most likely diagnosis?

17-α-hydroxylase deficiency

49-year-old woman presents with dysphagia. She is having difficulty swallowing liquids and solids, and she notes regurgitation of undigested food. X-ray reveals a bird's beak appearance of the esophagus. What is the most likely diagnosis?

Achalasia

44-year-old premenopausal Caucasian woman with a BMI of 36 presents with persistent upper right quadrant abdominal pain that radiates to the back. It has gotten so bad that she has difficulty eating any food and needs to force herself to eat. She has nausea with some episodes of vomiting. She denies bulimia but admits to anorexia. On exam, the patient has a positive Murphy's sign and tenderness to palpation in the epigastric and upper right quadrant area. Patient has a slightly elevated temperature. The physician assistant is awaiting labs and imaging. What is the most likely diagnosis?

Acute cholecystitis

24-year-old man is used to jogging 4 miles a day. Of late, he has had paroxysmal attacks of headaches and anxiety while exercising. A similar attack while urinating in the morning prompted a visit to the hospital. On examination, there is no pallor, icterus edema, or lymphadenopathy. His BP is 110/78 mm Hg. On funduscopy, however hypertensive changes are noted. Biochemical investigations reveal an elevated blood sugar level and increased levels of urinary VMA (vanillal mandelic acid). What is the most likely diagnosis?

Adrenal medullary tumor

40-year-old man is riding his bicycle and collides with a truck on the highway; he is severely injured, leading to significant blood loss. He is immediately rushed to the nearest hospital, where the attending resident immediately puts him on an intravenous supply of 0.9% NaCl before arranging for the blood that matches his group. In this patient, what would the intravenous administration of sodium chloride cause?

An increase in ECF volume with no change in osmolarity

35-year-old Hispanic man presents for an appointment but is too embarrassed to tell the nurse his chief complaint. You enter the room and coerce him to give you the reason he has come in to seek medical treatment. He admits to severe, intense itching around his anus that has been worsening the last several weeks. He further states that he has noticed increasingly severe and tearing pain in the anal area with each bowel movement. He would rank this pain as a 10/10 on a pain scale and it lasts hours afterward. This intense pain makes him not want to have any bowel movements. He admits to only 1 episode of a small amount of bright red blood on the toilet paper as well as on the stool itself. The patient denies fever, diarrhea, or ever being diagnosed with inflammatory bowel disease. What is this patient's most likely diagnosis?

Anal fissure

32-year-old man with no significant past medical history presented with dyspnea, palpitations, feelings of anxiety, and dizziness, all of which occurred earlier in the morning following a brisk walk. He denied any prior episodes, recreational drug use, alcohol or cigarette use, skipping meals, or caffeine intake. He further denied fever, chills, chest pain, history of murmurs, cough, edema, rashes, syncope, headache, psychiatric, or focal neurological problems. The physical examination demonstrated a fast and regular pulse with a constant-intensity first heart sound, but was otherwise normal. An EKG was performed, which revealed a short PR interval and a slurred upstroke at the beginning of the QRS complex. What is the most likely mechanism responsible for this patient's presentation?

Early excitation due to accessory pathways between the atria and ventricles

25-year-old Caucasian woman comes into the clinic for her appointment. She is complaining of not having a period for the last 6 months. She states that she has not had the money to see a doctor until now. She started her menstrual cycles at age 12, and they have been mostly irregular. Her flow lasted 5 days without significant cramping. She is a G 0 P 0 AB 0. Her vital signs are within normal limits. She is 5'10", 100 lb. A urine pregnancy test is negative. She states that she is just too fat. When asked how much she exercises, she replies that she runs 10 miles every day. What other information would be the first that you would want to know?

Eating habits

82-year-old man with a past medical history of hypertension, dyslipidemia, type 2 diabetes, and chronic kidney disease is being evaluated for progressive exercise-induced fatigue and shortness of breath over the last year. He also admits to more recent chest pain and lightheadedness, both of which occur with ambulation. He denies cough, fever, chills, lower extremity edema, or abdominal complaints. The physical exam revealed a narrow pulse pressure following blood pressure assessment. His cardiac exam noted a laterally displaced point of maximal impulse, as well as a mid-systolic ejection murmur that is low-pitched, rough, rasping in character, and loudest in the second right intercostal space. This murmur radiates to the bilateral carotid arteries. His peripheral vascular exam demonstrated a delayed peak of his radial pulsations. What diagnostic procedure would be best for this patient?

Echocardiography

11-year-old boy presents with increasing cognitive trouble in school. His parents state that he has had more trouble with grades and schoolwork since starting middle school. He also seems slightly more defiant. His history is significant for a metabolic disorder; it was diagnosed at birth, but it has been controlled with diet. He is interviewed while his parents are out of the room; mild cognitive impairment is noted. He tells you that, since he started middle school, he has been "cheating" on his diet. What laboratory finding would be expected in this patient?

Elevated serum phenylalanine

52-year-old woman presents with a 1-year history of bilateral shaking in her hands. The shaking tends to worsen when she is using her hands; her symptoms improve when she drinks a glass of wine on the weekends. Her 82-year-old mother also has a similar shaking in her hands that developed when she was in her 50s. What is the most likely diagnosis?

Essential tremor

51-year-old woman presents due to menstrual irregularity, hot flashes, and mood changes. Physical examination reveals an atrophic vagina and breasts that have decreased in size. She is diagnosed with menopause, and she decides not to start hormone replacement therapy (HRT). 8 years later, a dual-energy X-ray absorptiometry (DEXA) reveals a T score of -3. Change in the serum level of what substance is most likely responsible for her changes in bone mineral density?

Estrogen

19-year-old girl is brought to the emergency department by her sister who was unable to wake her up in the morning. According to her sister, the patient came home the night before with an alcoholic breath and was very upset after a fight with her boyfriend. She had always been healthy and does not use any medication, apart from occasional acetaminophen for headaches. Her family has a strong history of diabetes and autoimmune disorders. Her father has Hashimoto's thyroiditis and vitiligo, and her sister had a recent diagnosis of type 1 diabetes. Her grandmother, with whom she and her sister live, has been on insulin for several years. An initial metabolic panel before administration of IV glucose showed blood glucose levels of 1.77 mmol/L (32 mg/dL; normal, 70-115 mg/dL). C-peptide in the same sample was undetectable (normal 0.9-4.0 ng/mL). What is the most likely cause for this patient's hypoglycemia?

Exogenous insulin

46-year-old woman presents because she has not had her period for almost a year, has hot flashes, and feels fatigued most of the time. She complains of insomnia, and states that she keeps smoking despite trying many times to quit. Her libido is low and she does not use any hormone-based birth control. Her blood analysis indicates a TSH (thyroid-stimulating hormone) level of 3.1 mcU/mL and a FSH (follicle-stimulating hormone) level of 55.3 mIU/mL. What is the most accurate conclusion regarding the menstrual status of this patient?

FSH level is consistent with menopause.

82-year-old woman is brought in by her daughter due to fecal incontinence. The patient has been living with her daughter since a hip fracture 1 month earlier, and she did not have any problems with bowel continence until the last week. The patient is now noticing small amounts of runny stool in her underwear. The patient admits some abdominal discomfort, but she has trouble differentiating abdominal, pelvic, and hip discomforts after her recent fracture. She denies a known history of any gastrointestinal disorders, but she admits some constipation since her hip surgery. She denies any spinal cord trauma. She reports a history of chronic urinary incontinence, which has been controlled on oxybutynin. The patient has no other medical history. She has been taking oxycodone for post-surgical pain, over-the-counter diphenhydramine to help her sleep, and her usual oxybutynin. Her only surgery is the hip fracture repair. She is a non-smoker, and she denies alcohol and drug use. On physical exam, the patient appears slightly sedated; she is thin, with a slightly distended abdomen. She is diffusely tender over her abdomen. Rectal exam reveals a very large amount of stool in the rectal vault. The remainder of her exam is normal. What is the most likely diagnosis?

Fecal impaction

3-year-old girl presents with a 5-day history of purulent, foul-smelling nasal discharge. She is otherwise well-appearing, and her mother reports that she has not had any cough or fever. She is playful and eating and drinking normally. She stays with a babysitter during the day. Physical exam is remarkable for unilateral foul-smelling nasal discharge. What is the most likely diagnosis?

Foreign body

62-year-old woman presents with excruciating pain, burning, and swelling in her left forearm and wrist. She reports that symptoms initially began with a fracture 4 months ago. The fracture has healed, and she is frustrated by ther persistent symptoms. She cannot wear a jacket or long sleeves; the fabric touching her skin causes pain. Physical examination is remarkable for mild edema and erythema of her left forearm and tenderness with light touch. Distribution of findings includes the region from the elbow to wrist, anterior and posterior surfaces. Her left wrist strength and range of motion are decreased compared to the right. Distal pulses, capillary refill, and reflexes are normal. The remainder of the exam, including mental status, is normal. What medication would be most appropriate for the most likely diagnosis?

Gabapentin

32-year-old woman presents with increasing irritability. She reports involuntary movements of her arms and increasing incoordination. Her husband is worried because she is having trouble remembering things. She was adopted, and her family history is unknown. Physical examination is remarkable for rapid involuntary movements of fingers bilaterally, impaired ability to concentrate, slurred and disorganized speech, and difficulty responding with appropriate words or phrases when prompted. What test will best confirm the suspected diagnosis?

Genetic testing

15-year-old boy presents with concerns about puberty. He was adopted when he was 3 months old and has always been healthy. He has grown 6 cm in the last 4 months but remains shorter than his peers. Physical exam is remarkable for Tanner 1 pubic hair and prepubertal testes. This patient's symptoms are related to a delay in nocturnal release of what hormone?

GnRH

50-year-old woman undergoes a thyroid function test. The triiodothyronine (T3) level of a blood sample is higher than the normal. After equilibration of the sample with radiolabeled T3 and T3-binding substance (resin), T3 content of the resin is determined; it is found to be lower than the normal value. What is the most likely explanation for these laboratory findings?

Increased level of T3-binding proteins

A preterm newborn child is routinely evaluated 1 month following delivery. The mother reports that the child has been breathing quickly, has had difficulty feeding, and is not gaining weight. The physical exam is remarkable for tachypnea, diaphoresis, and below-normal weight. There is also a murmur that is located at the 2nd left intercostal space. The murmur is continuous throughout cardiac systole and diastole, nonradiating, and of a "machinery" quality. There is additionally a widened pulse pressure. The skin and mucosa is without cyanosis, and there is no evidence of fluid retention. A doppler-enhanced echocardiogram was performed, which was remarkable for the following findings shown in the image. What pharmacologic agent is the most preferred for this patient at this time?

Indomethacin

You are evaluating a 26-year-old man; he is suspected of being infertile. His past medical history is unremarkable. On examination, you note he is 6'4"; he has mild gynecomastia, sparse body hair, and small soft testes. What is the most likely diagnosis?

Klinefelter syndrome

92-year-old woman with Alzheimer's disease is brought in from her long-term care facility. She was found holding her abdomen and screaming in pain. She is unable to provide any history, but her aide states that the patient was incontinent of liquid stool shortly before being brought to the hospital. On examination, her abdomen is distended; there are no palpable masses. On rectal examination, there are firm feces in the rectal vault. What is the best initial treatment?

Mineral oil enema

80-year-old woman has a history of a myocardial infarction about 5 weeks ago. The patient now presents to the ED with a history of congestive heart failure with symptoms of shortness of breath and peripheral edema, which appear to be worsening since her MI. An ECG is conducted, which reveals a prior inferior wall infarct. Cardiology is consulted where a 2-dimensional echo is conducted, displaying severe leaflet tethering and an enlarged left ventricle. What structure is most likely to be affected?

Mitral valve

27-year-old man with Marfan syndrome presents due to exercise intolerance and heart palpitations. On exam, you note a mid-systolic click and late systolic murmur heard at the apex of the heart. The click and murmur are noted later in systole with squatting and earlier in systole with sudden standing. What is the most likely diagnosis?

Mitral valve prolapse

43-year-old Caucasian man with a 20-year history of bipolar disorder presents for the first time with long-term polyuria and polydipsia. He previously took lithium for mood stabilization for 15 years before initiating divalproex sodium therapy. He stopped using lithium because of the polyuria, but he felt that the polyuria never fully subsided. His weight is stable, and he has no other urinary complaints. His blood pressure is 115/80 mm Hg, and his physical exam is normal. His urinalysis shows no blood, cells, protein, glucose, nitrate, casts, or crystals. What is the most likely cause of his polyuria?

Nephrogenic diabetes insipidus

A preterm female infant born to a 32-year-old woman with no known past medical illnesses presents for the infant's 1-week follow-up. The mother reports that the patient is behaving normally and is feeding well. The physical exam is remarkable for a murmur, which is located at the second left intercostal space. The murmur is continuous throughout cardiac systole; it is diastolic, non-radiating, and of a "machinery" quality. There is also a widened pulse pressure. The skin and mucosa are without cyanosis, and there is no evidence of fluid retention. Based on the physical exam finding, what is the most likely diagnosis?

Patent ductus arteriosus

Mandatory newborn screening has been conducted on a neonate born 36 hours ago. The abnormality found in the screening has resulted in counseling on initiating lifelong modification to the newborn's diet. It is explained to the mother this action must be taken in order to help decrease the incidence of severe intellectual disability, hyperactivity, and even seizures. Considering the most likely diagnosis of this patient, what must be limited in order to prevent these consequences?

Phenylalanine

24-year-old man with no significant PMH presents due to increasing pain in his right groin and buttock and difficulty walking. The pain has been present and worsening for about 1 month. He further reports that he had significantly injured himself (also near his right hip) in a fall while snowboarding about 3 months ago. He did not seek immediate care and had difficulty ambulating for a week, then saw a chiropractor to "put his lower back back in." The pain and gait problems eventually improved. Now he is concerned because the pain has returned with no new history of trauma. He denies any family history for musculoskeletal and rheumatologic conditions. On physical exam, the patient was noted to walk with a slight limp. Examination of the hip, buttock, and groin region reveals no edema, erythema, or ecchymosis. The exam does not produce one particular point of tenderness with palpation, passive range of motion is limited and painful, especially with forced internal rotation. A straight-leg raise against resistance elicits pain. What diagnostic study would confirm this patient's condition?

Plain radiography (X-ray)

71-year-old male farmer presents because he is experiencing a gradual increase of frequency of urination over the previous 4-5 months. He has difficulties starting to urinate, the stream is slow, and he frequently has a sensation of incomplete emptying. He has not had a physical examination in several years. He has no history of sexually transmitted diseases (STDs) or urinary tract infections. Upon examination, his abdomen and his prostate are non-tender. His prostate seems moderately enlarged (estimated at 35 g) but smooth and symmetrical. What diagnostic test do you recommend as the next step in this patient's management?

Post-void residual urine test

This element is necessary for normal muscle and nerve function. Symptoms of deficiency include muscle weakness, abnormal ECG, and alkaline urine

Potassium

50-year-old man is evaluated for non-productive cough and shortness of breath. He reports a progressive cough that has worsened over the past year. Over the last 2 weeks, he has increasing cough, chest pain, and low-grade fever. His occupational history reveals coal mining for 25 years. He denies any smoking, alcohol consumption, travel history, or sick contacts. He also denies sore throat, otalgia, abdominal pain, peripheral edema, rashes, or pruritus. A chest radiograph was performed. Refer to the image.What treatment would be most beneficial?

Prednisone

42-year-old morbidly obese woman is referred back to her primary care provider to supervise her weight loss program. A surgeon evaluated her for a "gallbladder attack" 1 month ago, which then resolved. She currently denies abdominal pain. On ultrasound, there are visible stones in the gallbladder. She declined to have surgery until she achieves her initial weight loss goal of 50 pounds. She is on a supervised healthy diet of about 1200 kilocalories daily. She exercises 1 hour a day 6 days per week. She is losing about 15-16 pounds a month. What intervention would be most effective at preventing the recurrence of her gallbladder "attack" until she achieves her weight loss goal?

Prescribe ursodiol

Police bring a 30-year-old woman to the ER; she was raped a few hours ago. While you are obtaining the forensic evidence (using a rape kit), she tells you that she is worried about pregnancy. Her menstrual cycles are normal, and her last menstruation was 10 days ago. What emergency contraception should be considered?

Progesterone receptor modulator

25-year-old woman presents with chills, fever, and vaginal bleeding. She states that several hours ago she drank a special herbal mixture a friend had recommended; her period was late and she wanted to terminate a potential pregnancy. Physical examination and laboratory evaluation are not consistent with a urinary or genital tract infection. What was mostly likely present in the herbal mixture?

Prostaglandin

63-year-old woman is 4 days status post partial colectomy for colon cancer. Until now, her postoperative course has been uncomplicated, but today she is experiencing new onset of shortness of breath and chest pain. Her pulse is 120, respirations are 20, temperature is 38.6°C, and BP is 98/72. On examination, heart rate is regular but rapid. Her lung sounds are diminished bilaterally; some wheezing is heard. Her abdomen is soft and mildly tender, with a well-healing midline incision. EKG reveals sinus tachycardia. What is the gold standard test for her suspected condition?

Pulmonary angiography

43-year-old man presents with a "sore" near his rectum. He reports rectal pain with bowel movements; there is some anal discomfort with sitting and physical activity. He notes occasional drainage from the lesion and rectal pruritus. He denies anal intercourse, unusual travel, and other skin lesions. He has tried over-the-counter hemorrhoid treatments without relief. Past medical history is significant for Crohn's disease; he is not being treated for it currently. He has no known allergies and takes no medications. He is married/monogamous; he works as a bartender and denies the use of tobacco and recreational drugs, with occasional alcohol use. On physical exam, a single 4 mm pustule-like lesion is visualized on the perianal skin about 2 cm from the anus. No other skin lesions are found. Rectal exam is normal. What is the most likely diagnosis?

Rectal fistula

47-year-old man presents with a 6-month history of intermittent abdominal pain. He notes that his episodes of pain developed after eating large amounts at holiday parties or work events. During episodes, his pain is located in the right upper quadrant without radiation, is described as sharp, and is accompanied by nausea. He is currently pain free. On examination, his abdomen is soft, nontender, and nondistended. He is afebrile. Labs are as follows: Component Value WBC 6.24 Hemoglobin 16.8 Hematocrit 49.6 Platelets 187 Bilirubin total 1.4 Alkaline phosphatase 48 AST 14 Glucose 95 BUN 8 Creatinine 1.03 Sodium 143 Potassium 3.7 Chloride 105 CO2 30 ALT 11 An abdominal ultrasound shows the presence of multiple gallstones with some sludge. The common duct is normal. There is no pericholecystic fluid present. No sonographic Murphy's sign is detected. What is the proper course of action?

Referral to a surgeon for elective laparoscopic cholecystectomy

27-year-old man is admitted to the hospital following a motor vehicle accident. He sustained lacerations to his arms bilaterally and has fractures of the right tibia and fibula. A cast is placed and the patient is scheduled for surgery the following day. A few hours after the cast is placed, he develops severe pain; the pain is unresponsive to several doses of intravenous morphine. His pain increases when he extends his right leg. Peripheral pulses are weak but present. Based on the history and physical, what should be done next?

Remove cast and check compartment pressure.

72-year-old man presents with "being short of breath"; he feels as though his belly is bloated and his legs are swollen. Past medical history includes high blood pressure (for which he is currently taking lisinopril) and high cholesterol controlled with diet modifications. The patient also has a past diagnosis of mediastinal lung cancer around 5 years ago for which he received radiation treatment as part of his prescribed therapeutic regimen. Physical examination reveals an elevated jugular venous pressure and Kussmaul sign. Moderate pitting edema and ascites are also observed. Chest radiograph reveals only mild cardiomegaly. Echocardiogram reveals a normal left ventricle chamber size, normal LVEF, and a thickened atrial septa. What is the most likely diagnosis?

Restricted cardiomyopathy

62-year-old woman presents to her OB/GYN clinic for an annual exam. She reports stretch marks and a 20 lb weight gain, noticeable in her face. She feels fatigued and irritable and has no sex drive. She notes increased dark chin hairs and easy bruising. She denies blood in stool, fever, chills, foreign travel, changes in sexual partners, and suicidal thoughts. Past medical history is significant for asthma, with periodic hospitalizations for asthma attacks. Menopause at 51. No surgeries or allergies. She takes prednisone 40 mg daily, fluticasone propionate/salmeterol twice daily, and an albuterol inhaler as needed for asthma. She denies tobacco, alcohol, and recreational drugs. BMI is 30 and blood pressure is 162/92 mm Hg. On physical exam, she has a rounded, full face, striae on her abdomen, hirsutism on her chin and abdomen, a large fat deposit on the upper back, an obese abdomen, with some muscle wasting on extremities. What is the most appropriate intervention for this condition?

Taper off daily prednisone.

16-year-old girl presents with amenorrhea. Physical examination reveals a normal female body habitus except for scant axillary and pubic hair. Pelvic examination reveals a shallow vagina with no cervix. A mobile mass can be palpated in the left labium majorum. Ultrasonographic examination reveals a complete lack of uterus and adnexal structures. What is the most likely reason the uterus and uterine tubes are absent in this patient?

The patient has androgen insensitivity syndrome.

44-year-old man presents after an episode he describes as "passing out." He has a past medical history of hypertension, diabetes mellitus type 2, and osteoarthritis. Earlier in the day, the patient visited his primary care physician for routine blood work. During his blood draw, the patient had an acute onset of syncope. The patient has never had such an episode before. Vital signs upon presentation are as follows: BP 124/82 mm Hg, P 88 beats/min, R14/min. EKG is within normal limits. Cardiovascular examination reveals a normal S1 and S2, with no rubs, murmurs, or gallops. The patient is being treated with atenolol and hydrochlorothiazide for his hypertension. His blood sugar is 96 mg/dL. What is the most likely cause of the patient's syncope?

Vasovagal episode

62-year-old woman presents due to urine leakage for 2 years that has worsened. She leaks urine when she coughs or sneezes; she wears a pad daily as a result. The amount of leakage varies. The patient denies hematuria, dysuria, and pelvic pain. She sometimes feels vaginal pressure and fullness. She is considering quitting her job from embarrassment. Past medical history includes 4 vaginal deliveries. No other known medical conditions, medications, or allergies. She is married and works part-time at a call center; she denies tobacco, alcohol, and recreational drugs. On physical exam, she is obese, with an atrophic vulva/vagina. Pelvic examination reveals downward and forward rotation of the vaginal wall, with an anterior bulging when the patient is asked to strain. A dipstick urinalysis is normal. After completing treatment of her condition, what is the most appropriate way of preventing recurrence?

Weight loss

At low Ca2+ concentrations in the cytosol of smooth muscle (<ï¾ 1ï¾ μM), caldesmon binds to which complex to prevent its interaction with myosin, thus causing relaxation?

actin-tropomyosin

34-year-old Caucasian man comes to you in the winter complaining of lack of energy, weight loss, loss of appetite, nausea and vomiting, and increased skin pigmentation as if he had a tan. On physical examination, his heart rate is 120, his blood pressure is 85/65. Blood tests reveal that he is hyponatremic, hyperkalemic, has depressed cortisol, and elevated ACTH. The most likely diagnosis is Addison disease most commonly caused by autoimmunity. This condition would be MOST effectively treated by which of the following?

glucocorticoids and mineralocorticoids

25-year-year old man received a severe laceration across his larynx in a street fight. During his hospitalization for recovery from emergency surgery, he experienced tetany and seizures. His serum Ca2+ values were significantly lowered. The decreased serum Ca2+ would most likely to be due to a decline in secretion of parathyroid hormone. Which statement most accurately describes the first step in the fundamental physiologic mechanism of action of this hormone?

increase in cAMP in bone cells

A 3-year-old child is brought to a pediatrician by a concerned father who reports that his child is easily fatigued after play, becoming exhausted and breathing heavily. The pediatrician finds significant cyanosis in the child and a systolic murmur. Further tests lead to the diagnosis of tetralogy of Fallot. Catheterization of the right ventricle would show which of the following?

increased systolic pressure

20-year-old college student recently noticed difficulty with controlling muscles on the right side of his face. Additionally, he had become extremely sensitive to loud noises on his right side. He went to the campus health facilities, where a physician observed right-sided hyperacusis, inability of the right eyelid to close, loss of taste sensation from the right, anterior portion of the tongue, and weakness of upper and lower facial muscles on the right side of the face. He made a prompt diagnosis of Bell palsy and advised the patient to get some rest but not to worry too much. Which of the following BEST illustrates the path of taste sensation from the anterior two-thirds of the tongue to the brain?

lingual nerve, chorda tympani, facial nerve, nucleus solitarius, VPM thalamus, postcentral gyrus

33-year-old woman complains of double vision and drooping upper eyelids. Initially, her visual and eyelid symptoms were transient, but now they are constant. Her voice is nasal and weak, and with prolonged talking, her voice fatigues to the point of unintelligibility. She states that her throat becomes tired when she eats a large meal. Her face shows little movement and when she attempts to smile, her expression resembles a snarl more than a smile. As she speaks, she holds her hand under her jaw. Blood tests reveal an abnormally high titer of antibodies to human acetylcholine receptors. The symptoms are due to which of the following?

loss of acetylcholine receptors at the neuromuscular junction

Figure E2.4 is a diagram of the brachial plexus. The anterior rami of C5, C6, C7, C8 and T1 form the roots of the plexus. The middle cervical ganglion (MCG) of the sympathetic chain communicates with the C5 and C6 roots, the lower cervical ganglion (LCG) communicates with the C7 and C8 roots, and the first thoracic ganglion (1TG) communicates with the T1 root. The C5 and C6 roots unite to form the upper trunk (UT), the C7 root extends to become the middle trunk (MT), and the C8 and T1 roots unite to form the lower trunk (LT) of the plexus. The anterior divisions of the upper and middle trunks unite to form the lateral cord (LC), the posterior divisions of all three trunks unite to form the posterior cord (PC), and the anterior division of the lower trunk extends to become the medial cord (MC) of the plexus. Figure E2.5 displays 10 sites in the brachial plexus at which injury can produce serious losses of muscle action and skin sensation in the upper limb. There are two sites displayed in Figure E2.5 at which a severe injury could markedly diminish sensation on the medial aspect of the forearm and arm. Identify the MORE PROXIMAL site.

lower trunk

Figure E2.4 is a diagram of the brachial plexus. The anterior rami of C5, C6, C7, C8 and T1 form the roots of the plexus. The middle cervical ganglion (MCG) of the sympathetic chain communicates with the C5 and C6 roots, the lower cervical ganglion (LCG) communicates with the C7 and C8 roots, and the first thoracic ganglion (1TG) communicates with the T1 root. The C5 and C6 roots unite to form the upper trunk (UT), the C7 root extends to become the middle trunk (MT), and the C8 and T1 roots unite to form the lower trunk (LT) of the plexus. The anterior divisions of the upper and middle trunks unite to form the lateral cord (LC), the posterior divisions of all three trunks unite to form the posterior cord (PC), and the anterior division of the lower trunk extends to become the medial cord (MC) of the plexus. Figure E2.5 displays 10 sites in the brachial plexus at which injury can produce serious losses of muscle action and skin sensation in the upper limb. Assuming that the brachial plexus has been injured at one of the sites displayed in Figure E2.5, identify the ONLY site at which a severe injury would diminish sensation at the tip of the middle finger more markedly than it diminishes sensation at the tips of the thumb and little finger.

middle trunk

Decreasing an airway diameter by half would lead to which degree of change in airway resistance?

more than 100% increase

33-year-old woman complains of double vision and drooping upper eyelids. Initially, her visual and eyelid symptoms were transient, but now they are constant. Her voice is nasal and weak, and with prolonged talking, her voice fatigues to the point of unintelligibility. She states that her throat becomes tired when she eats a large meal. Her face shows little movement and when she attempts to smile, her expression resembles a snarl more than a smile. As she speaks, she holds her hand under her jaw. Blood tests reveal an abnormally high titer of antibodies to human acetylcholine receptors. The MOST likely diagnosis is which of the following?

myasthenia gravis

60-year-old African-American woman was examined in a routine physical examination. Her height was within normal limits. She was found to have kyphosis. She showed marked enlargement of the bones of the extremities and significant coarsening of her facial features. Her jaw was protrusive and enlarged. The MOST likely diagnosis of her condition is acromegaly. Magnetic resonance imaging of her head would most likely reveal which of the following?

pituitary tumor

Figure E2.4 is a diagram of the brachial plexus. The anterior rami of C5, C6, C7, C8 and T1 form the roots of the plexus. The middle cervical ganglion (MCG) of the sympathetic chain communicates with the C5 and C6 roots, the lower cervical ganglion (LCG) communicates with the C7 and C8 roots, and the first thoracic ganglion (1TG) communicates with the T1 root. The C5 and C6 roots unite to form the upper trunk (UT), the C7 root extends to become the middle trunk (MT), and the C8 and T1 roots unite to form the lower trunk (LT) of the plexus. The anterior divisions of the upper and middle trunks unite to form the lateral cord (LC), the posterior divisions of all three trunks unite to form the posterior cord (PC), and the anterior division of the lower trunk extends to become the medial cord (MC) of the plexus. Figure E2.5 displays 10 sites in the brachial plexus at which injury can produce serious losses of muscle action and skin sensation in the upper limb. Assuming that the brachial plexus has been injured at one of the sites displayed in Figure E2.5, identify the ONLY site at which a severe injury could cause the triceps brachii deep tendon reflex to be absent.

posterior cord

A male patient had been experiencing gastric ulcers for several years. Attempts by his physician to treat his condition with antibiotics have been unsuccessful. Lifestyle changes to decrease stress, caffeine, and alcohol have also been unsuccessful. As a last resort, his physician recommends surgery. Such a surgery would MOST likely interrupt supply of which type of fibers to the stomach?

preganglionic parasympathetic

32-year-old mother of two children has 6-month history of amenorrhea, galactorrhea, and loss of libido. Her history is otherwise unremarkable and her β-hCG titer is undectable. The most likely cause of her symptoms is an adenoma of acidophils. Blood tests would be MOST likely to reveal an elevation of which hormone?

prolactin

29-year-old woman visits her obstetrician/gynecologists. She and her husband have been trying unsuccessfully to have a child. She also notes that weight gain, increased facial hair, and lack of menses. A pelvic examination reveals normal external genitalia but palpation reveals that both ovaries are enlarged. Her blood chemistry shows elevated LH, decreased FSH, and abnormal steroid levels. The most likely diagnosis is Stein-Leventhal syndrome. The hirsutism is due to excessive production of which of the following?

testosterone

16-year-old female comes to your office complaining of amenorrhea. Physical examination reveals a normal female body habitus except for scant axillary and pubic hair. Pelvic examination reveals a shallow vagina with no cervix. A mobile mass can be palpated in the left labium majorum. Ultrasonographic examination reveals a complete lack of uterus and adnexal structures. The MOST likely diagnosis on this patient is testicular feminization syndrome. This patient would lack an epididymis because of which of the following reasons?

their differentiation is testosterone dependent

Figure E2.4 is a diagram of the brachial plexus. The anterior rami of C5, C6, C7, C8 and T1 form the roots of the plexus. The middle cervical ganglion (MCG) of the sympathetic chain communicates with the C5 and C6 roots, the lower cervical ganglion (LCG) communicates with the C7 and C8 roots, and the first thoracic ganglion (1TG) communicates with the T1 root. The C5 and C6 roots unite to form the upper trunk (UT), the C7 root extends to become the middle trunk (MT), and the C8 and T1 roots unite to form the lower trunk (LT) of the plexus. The anterior divisions of the upper and middle trunks unite to form the lateral cord (LC), the posterior divisions of all three trunks unite to form the posterior cord (PC), and the anterior division of the lower trunk extends to become the medial cord (MC) of the plexus. Figure E2.5 displays 10 sites in the brachial plexus at which injury can produce serious losses of muscle action and skin sensation in the upper limb. Assuming that the brachial plexus has been injured at one of the sites displayed in Figure E2.5, identify the ONLY site at which a severe injury could (I) completely paralyze the muscles that initiate abduction of the arm from the anatomic position, AND (II) cause the biceps brachii deep tendon reflex to be absent, AND (3) markedly diminish sensation on the lateral aspect of the arm and forearm.

upper trunk

Examine Figure I2.1 below. It is a diagrammatic representation of the nervous system. Which lettered structure represents autonomic preganglionic fibers synapse with ganglionic fibers that release a neurotransmitter that uses inositol triphosphate as a second messenger?

A

A 39-year-old woman visited her neurologist after an episode of fainting followed by several hours of unconsciousness. Upon regaining consciousness, she appeared confused and was unable to speak. Examination reveals a spastic paralysis of the right arm but no atrophy. The right leg and both left extremities appear normal. Her tongue protrudes to the right but is not atrophic. Her right facial muscles below the eye are paralyzed. There are no apparent deficits in pain, temperature, or other somesthetic modalities. There appear to be no visual deficits. The patient suffered from subacute bacterial endocarditis about 18 months ago. What diagram most accurately depicts the extent of this patient's lesion?

A

A healthy 42-year-old woman with a history of anxiety attacks sits in the hospital waiting room as her 3-year-old daughter undergoes open heart surgery for a septal malformation. The woman experiences a feeling of suffocation and is obviously hyperventilating. She informs her husband that she feels faint and has blurred vision. What is the best treatment to relieve the symptoms caused by her hyperventilation?

Breathing in and out of a paper bag

32-year-old pregnant woman is told by her physician to avoid taking aspirin. Use of aspirin is contraindicated, especially during the last part of pregnancy. What hemotogic parameter is affected by aspirin?

Bleeding time

For a television game show, 16 contestants volunteer to be stranded on a deserted island in the middle of the South China Sea. They must rely on their own survival instincts and skills. During one of the challenges, one team wins a fishing spear. They catch a puffer fish and cook it over the open flames of their barbecue. None of them are very skilled in cooking, but they enjoy the fish anyway. One of the contestants, a worldwide traveler, comments that it tastes like Fugu. After dinner, they all develop a strange tingling around their lips and tongue. They all become weak, and their frailty progresses to paralysis. All of the contestants die. What is the mechanism of toxicity?

Blockage of the sodium gates

36-year-old man comes into the emergency department with a history of vomiting, constipation, ocular palsy, pharyngeal paralysis, and muscular weakness. He says he has recently returned from hiking with his friend, during which he consumed canned meat for dinner. On examination, he was found to have a depressed pupillary reflex, gag reflex, and slightly below normal deep tendon reflexes. Edrophonium test is falsely positive. Based on the above tests, what is the most likely diagnosis in this patient?

Botulism

45-year-old obese multipara woman presents with abdominal discomfort and pain after meals, more severe after a fatty meal. Sometimes it is associated with nausea. What hormone is increasing the discomfort and pain?

Cholecystokinin

48-year-old man presents with continuous right upper quadrant pain that developed after eating fried chicken. He has experienced previous episodes of less severe right upper quadrant pain that resolved spontaneously. The pain radiates to his right shoulder, accompanied by nausea, vomiting, and chills. Vital signs include BP 120/85 mm Hg, pulse 117/min, respirations 18/min, temperature 102.5°F. Physical examination is remarkable for scleral icterus and jaundice. His abdomen is slightly distended with right upper quadrant tenderness and a positive Murphy sign. CBC reveals mild leukocytosis, elevated serum aminotransferases and bilirubin, and normal lipase. What is the most likely cause of this patient's symptoms?

Choledocholithiasis

77-year-old man presents to the emergency department with chest pain and difficulty breathing. His heart rate is 120 beats/minute and blood pressure is 70/45 mm Hg. Physical examination is remarkable for cool extremities, and urinary output is minimal. Despite aggressive fluid resuscitation, the patient's symptoms appear to be worsening. Bedside ECG indicates ST elevation in leads II and III and aVF. Hemodynamic monitoring indicates large V waves on PCWP tracing. How would this patient's shock be categorized?

Cardiogenic shock

40-year-old alcoholic woman presents with a history of abdominal pain. She has been experiencing weight loss even after a normal diet intake. A few days ago she noticed oily, bulky, and foul-smelling stools. Lab reports reveal the presence of fat droplets and undigested meat fibers in the stool. The other reports were: bleeding time 4 minutes, clotting time 7 minutes, hemoglobin 10 g%, packed cell volume 35%, WBC 18,000/cu mm of blood, ESR 40 mm at the end of 1st hour, amylase 45 units/dL, albumin 2.8 g/dL, and bilirubin 1.2 mg/dL. The patient was treated symptomatically and advised to follow a low-fat diet. She also joined Alcoholics Anonymous and gave up alcohol use. A few weeks later she started experiencing weight gain and also reported normal stools. What is the most likely diagnosis?

Chronic pancreatitis

35-year-old man presents with recurrent headaches. They occur on one side of his head and feel like sharp stabbing pain just above his left eye. He notes eye redness and watering with the headaches. Each headache lasts for 2 hours, and they have been occurring daily for 2-3 weeks. He reports a similar pattern of headaches last year. He denies any known family history of headaches similar to his or migraines. Physical examination is within normal limits. What is the most likely diagnosis?

Cluster headache

31-year-old woman has hypertension (205/105) that has not responded to ACE inhibitors. She has also experienced progressive muscle weakness. Her blood chemistry reveals hypokalemia and hypernatremia, normal glucose, and elevated bicarbonate. Some adrenal cortical steroids are elevated and her renin is depressed. An abdominal CT-scan reveals a mass in her left adrenal cortex (Figure C21.9). Surgical excision of the left adrenal gland was curative. The MOST likely diagnosis is which of the following?

Conn syndrome

The academic achievement of a straight-A high male school student starts to fall. He also develops an unexplained tremor in his arms and dysarthria. His neurologic symptoms progress before he is finally seen by his family physician. A slit lamp examination reveals that his cornea has a distinctive yellow-brown ring. His laboratory results are as follows: TEST RESULTS REFERENCE RANGE Calcium 9.8 mg/dL 8.5-10.5 mg/dL Potassium 4.2 mEq/L 3.5-5.0 mEq/L Sodium 141 mEq/L 135-145 mEq/L Ceruloplasmin 16 mg/dL 20-45 mg/dL TIBC 275 μg/dL 250-375 μg/dL Plasma iron 100 μg/dL 50-150 μg/dL Transferrin saturation 30% 20-40% His symptoms are due to the accumulation of what substance?

Copper

30-year-old Hispanic woman asks for recommendations for contraception. She is a non-smoker with a history of thrombophlebitis, obesity, and hypertension; there is also a maternal family history of breast cancer. What method would have the best safety and effectiveness profile for this patient?

Copper IUD (intrauterine device)

25-year-old overweight African American man presents with concerns about his blood pressure. 3 months ago, he reports elevated blood pressure at a work health fair. He has checked his blood pressure in local grocery stores and he knows that the readings were "above normal." He has a strong family history of hypertension. His blood pressure is 175/95 mm Hg in the left arm and 172/99 mm Hg in the right arm. What will most likely be seen on fundoscopic examination?

Cotton-wool patches

Examine Figure I2.1 below. It is a diagrammatic representation of the nervous system. Which lettered structure represents parasympathetic postganglionic fibers which use acetylcholine as a neurotransmitter?

D

34-year-old woman presents with a 6-month history of progressive fatigue. She has had to stop running due to lack of energy, and she is napping frequently. She has a poor appetite, dry skin, and darkening of the skin over her elbows and knees. Physical examination is significant for orthostatic hypotension and hyperpigmentation of the elbows and knees. Basic metabolic panel: Component Value Range Sodium 125 135-146 mmol/L Potassium 5.3 3.5-5 mmol/L Chloride 79 98-107 mmol/L Bicarbonate 23 23-32 mmol/L Glucose 95 65-100 mg/dL BUN 17 8-25 mg/dL Creatinine 0.7 0.8-1.30 mg/dL What testing is recommended to confirm her diagnosis?

Cosyntropin stimulation test

The mother of a 3-year-old boy states that her child does not walk normally. The mother feels that the child has been falling more frequently; she also tells you that his symptoms are worsening quickly. On exam, the child uses his hands to push himself into an upright position from sitting on the ground. He walks with a waddling gait. There is hypertrophy of the bilateral calves, lumbar lordosis, and hyporeflexia. There is also cognitive delay. His labs reveal an increased creatine kinase. What is the most likely diagnosis?

Duchenne muscular dystrophy

60-year-old man undergoes valve replacement surgery for treatment of a severely calcified mitral valve. He is put on regular anticoagulation with warfarin to maintain a prothrombin time of 18 sec. He is stable and maintained well with this therapy. Subsequently, trimethoprim-sulfamethoxazole therapy is begun for recurrent urinary tract infections. Given his history, what other intervention would be most appropriate?

Decrease the dosage of warfarin

54-year-old alcoholic presents with complaints of tremors and muscle twitching. Physical examination reveals the presence of Trousseau's sign. Laboratory data show that serum magnesium is < 1 mEq/L (normal, 1.4 - 2.2 mEq/L). What finding would be most consistent with this information?

Decreased serum calcium

45-year-old woman presents with vaginal itching and irritation that did not resolve with over-the-counter medications. She has not previously sought medical attention for the symptoms. During review of systems, she admits to polyuria, polydipsia, and occasional dysuria, which she attributes to the vaginal irritation. She states she has not had lab work done in over a year, but the last time she did was at a health fair; she was told her fasting glucose was 119 mg/dl. On exam, you note that the patient is 62 inches tall and weighs 243 pounds. Her vital signs are within normal limits except for her blood pressure, which is 138/84 mm Hg. You find that she has white discharge in the vaginal canal; there is beefy-red surrounding skin and similar irritation under her breasts. Based on the patient's presentation, what is the patient's most likely underlying condition?"

Diabetes mellitus

A healthy 25-year-old man lives at the beach. His twin brother has been living in a mountain cabin for the past 2 years. What value would most likely be higher in the man living at sea level?

Diameter of pulmonary vessels

52-year-old Caucasian man who frequently visits the emergency department presents due to "being short of breath." He is currently homeless, in and out of shelters. Past presenting problems that have brought him to the emergency department indicate that he has a chronic issue with alcohol overuse. Today, the patient is experiencing severe shortness of breath at rest. Physical examination findings reveal rales auscultated in bilateral lung fields, an S3 gallop, and elevated JVP. What is the most likely diagnosis?

Dilated cardiomyopathy

57-year-old woman presents with progressive dyspnea and lower extremity edema. She has noticed the symptoms occurring over the last 3 months and also notes increasing fatigue over the last year. Past medical history is significant for diabetes and hypertension. Past social history is significant for previous alcohol abuse; patient has been sober for approximately 5 years. On physical examination, an S3 gallop is heard. Electrocardiogram reveals ST-T changes. Echocardiogram reveals left ventricular dilatation with an ejection fraction of 35%. What is the most likely diagnosis in this patient?

Dilated cardiomyopathy

65-year-old African-American man presents to establish care. He changed jobs, so he has new health insurance. You participate in a panel of providers associated with his insurance carrier. He presents with intermittent claudication when walking his dog. His blood pressure is 125/75 mm Hg. His ankle-brachial index (ABI) is 0.8. Labs include a normal white blood count and erythrocyte sedimentation rate. What factor elicited during history or found during the exam may have contributed to the reduced ABI?

History of chronic kidney disease

29-year-old woman presents with a 3-month history of increasing fatigue and weakness. She has lost 10 lb in 3 months. She has frequent nausea and abdominal pain. Physical examination is remarkable for hyperpigmentation of her knuckles, elbows, and knees. Labs are significant for mild leukocytosis, hyponatremia, and hyperkalemia. This patient will require long-term treatment with what medication?

Hydrocortisone

41-year-old woman has been hospitalized for over a week. Her laboratory results reflect an electrolyte abnormality and her EKG demonstrates peaked T waves and a widening of the QRS complex. These EKG abnormalities are characteristic of what condition?

Hyperkalemia

Your brother-in-law calls you because he had health fair labs at work and the lab tech advised him to see a health care provider for "out-of-range" values. He was told this problem could put him at risk for heart disease, blockages in his blood vessels, and pancreatitis. He cannot remember the value(s) that was/were out of normal range. He says he feels fine, but he wants your advice. He is not worried; he reports that he has no medical conditions, and there is no family history of cardiovascular disease. Your brother-in-law is 42 years old. He has a BMI of around 30, and he is a non-smoker; he eats poorly, drinks moderate amounts of alcohol, and does not exercise regularly. What is the most likely diagnosis?

Hypertriglyceridemia

51-year-old woman presents with muscular weakness. Upon questioning, she acknowledges that she usually awakens a couple of times at night to urinate. On physical examination, her blood pressure is 163/97 mm Hg. Further workup is done, and she is found to have primary aldosteronism, secondary to an adrenal adenoma. What electrolyte abnormality is probably present?

Hypokalemia

40-year-old woman comes to the gynecologist because she has missed her menstrual period for the last 6 months. She also says that even though she has frequent sexual activity, she does not get pregnant despite not using any form of birth control. At her physical exam, the patient exhibited a male hair pattern distribution. A sonogram shows 14 follicles in the left ovary. Pregnancy test is negative. What will be a probable finding in this patient?

LH/FSH ratio >2 and increase in androgens

33-year-old G5P4 woman presents to her gynecologist. She has been using condoms and would like to discuss alternative birth control options. She has regular periods and is not currently trying to get pregnant. She is sexually active with one partner. Past medical history includes asthma, deep vein thrombosis during her first pregnancy, and a C-section for her fourth pregnancy. She has no known drug allergies. What is the best birth control option for this patient?

Levonorgestrel IUD

A follow-up study assessed the role of two treatment regimens in the risk of cardiovascular outcomes: high-dose hydrochlorothiazide (100 mg) and low-dose hydrochlorothiazide (25 mg). The mean systolic blood pressure (BP) in the high-dose group was 139 mm Hg, and the mean diastolic BP was 88 mm Hg. In the low-dose group, the mean values were 143 mm Hg and 92 mm Hg, respectively. A two-sample t-test gave a p value of 0.03 for systolic and 0.04 for diastolic blood pressure differences between the two groups. The relative risk (RR) of sudden cardiac death comparing the low-dose group to the high-dose group was 0.4 (95% confidence interval 0.25-0.55). What is the most accurate analysis of the results of the study?

Low-dose hydrochlorothiazide reduces risk of sudden death by 60%.

A patient, who appears to be female, is found to be 46,XY. The patient's vagina is very shallow, ending in a blind pouch, and there are palpable masses in the labia. The diagnosis of androgen insensitivity syndrome is made. What was most likely present during the early fetal life of this individual?

MIF (Mullerian inhibitory factor)

39-year-old woman presents due to persistent urinary incontinence. She sustained severe injuries to her brain, spine, and pelvis 6 months ago in a car accident. She reports dribbling urine without being aware of it throughout the day and night. She feels no sense of urgency or sudden desire to void. She reports decreased sensation around her anus. Her urinary stream is normal. Evaluation of her bladder demonstrates a large flaccid bladder with a normal wall, low pressures, and high residual volume. What is the most likely location of her injury?

Sacral spine

A 65-year-old Caucasian man has a 40-pack-year history of cigarette smoking. He is found to have a spot on his lung after a chest X-ray. A biopsy confirms that he has small cell carcinoma of the lung, and he is admitted to the hospital. Over the course of the next few days, he develops lethargy and confusion and then proceeds to have a seizure. His urine output remains normal. Laboratory tests are performed on his blood and his urine. The results are as follows: TEST RESULTS REFERENCE RANGE Glucose (fasting) 72 mg/dL 65-110 mg/dL Sodium 121 mEq/L 135-145 mEq/L Potassium 4.0 mEq/L 3.5-5.0 mEq/L BUN 11.2 mg/dL 10-20 mg/dL Urine dipstick blood negative negative Urine dipstick glucose negative negative Urine dipstick ketones negative negative Urine dipstick protein negative negative Urine specific gravity 1.055 1.001-1.035 Water restriction is started and his symptoms improve. What is the most likely diagnosis?

Syndrome of inappropriate ADH secretion (SIADH).

54-year-old woman presents to her primary care physician due to persistent fatigue. She notes feeling more thirsty than usual, and she has been getting up several times throughout the night to urinate. Her physician obtains the following labs: Fasting blood glucose 170 mg/dL 2 hour oral glucose tolerance test 230 mg/dL Hemoglobin A1C 9% What is the most likely diagnosis in this patient?

Type II diabetes mellitus

An otherwise healthy 70-year-old man presents with age-related changes that are affecting his ordinary activities of daily living. Those changes are most likely related to the function of what organ system?

Urinary system