Question 1

In an elite marathon runner, performance in a marathon race is limited by a number of factors. Among world class marathon runners, which of the following factors is considered to be critical for a high level of performance?
A) Muscle ATP content
B) Adequate fat stores
C) High muscle glycogen content
D) High muscle oxidative capacity
E) High percentage of type II muscle fibers

Accepted Answer

High muscle oxidative capacity is considered to be critical for a high level of performance among world class marathon runners. This is because marathon running is an endurance event that requires the ability to sustain a high level of energy production over a long period of time. Muscle oxidative capacity refers to the ability of muscles to use oxygen to produce energy, and it is a key factor in determining an athlete's endurance performance.

Question 2

A 45-year-old woman complains of episodic epigastric pain. She denies fevers, chills, diaphoresis, flushing, chest pain or shortness of breath. An upper endoscopy reveals severe and atypical peptic ulcer disease. Biopsy results are Helicobacter pylori negative and she denies taking NSAIDs. Continued workup should include serum levels of which of the following?
A) Serotonin
B) Gastrin
C) Vasoactive intestinal peptide (VIP)
D) Cholecystokinin (CCK)
E) Histamine

Accepted Answer

Given the presentation of severe and atypical peptic ulcer disease with negative Helicobacter pylori biopsy and no NSAID use, the next step in the workup should include checking serum gastrin levels. This is to evaluate for Zollinger-Ellison syndrome, a condition characterized by gastrin-secreting tumors (gastrinomas) that cause excessive gastric acid production leading to peptic ulcers.

Question 3

Your 74-year-old male patient suffers from hyperthyroidism. Hyperthyroid individuals characteristically exhibit:
A) Heat tolerance
B) A low basal metabolic rate (BMR)
C) Decreased peripheral resistance
D) Dry, yellowish skin
E) High plasma cholesterol levels

Accepted Answer

Hyperthyroidism increases the basal metabolic rate (BMR), leading to increased heat production. This condition often results in decreased peripheral resistance due to the vasodilation effect of excess thyroid hormones, which can improve blood flow and reduce resistance in peripheral blood vessels.

Question 4

An 18-year-old male complains about continuous growth, lack of facial hair, small genitalia and lack of muscle development. Laboratory values include total testosterone 125 ng/dL (normal 300-1100 ng/dL) and luteinizing hormone (LH) < 2 mIU/mL (normal 6-23 mIU/mL). A major causal factor in some cases of hypogonadism is:
A) Increased number of follicle stimulating hormone (FSH) receptors in the testis
B) Hypersecretion of pituitary LH and FSH as the result of increased gonadotropin-releasing hormone (GnRH)
C) Excess secretion of testicular activin by Sertoli cells
D) Failure of the hypothalamus to respond to testosterone
E) Reduced secretion of GnRH

Accepted Answer

The patient's symptoms and lab values indicate hypogonadism with low testosterone and low LH levels, suggesting a central (secondary) cause. Reduced secretion of GnRH by the hypothalamus would lead to decreased stimulation of the pituitary gland, resulting in low levels of LH and subsequently low testosterone production, aligning with the patient's condition.

Question 5

A 79-year-old woman presents to the emergency department with right lower quadrant abdominal pain of several hours' duration. She has a temperature of 101.7º C and has tenderness to palpation in the right lower quadrant of her abdomen. Abdominal computed tomography (CT) scan reveals diverticulitis of the colon. Where are diverticula most frequently found in the colon?
A) Cecum
B) Ascending colon
C) Transverse colon
D) Descending colon
E) Sigmoid colon

Accepted Answer

Diverticula are most frequently found in the sigmoid colon. This is due to the high intraluminal pressures in this part of the colon, which predispose to the formation of diverticula.

Question 6

You see a 78-year-old man in clinic for his annual physical. He reports excellent health. During your review of systems, he admits to having difficulty initiating his urine stream, nocturia, and occasionally feels as if he does not completely empty his bladder. Routine lab tests show a normal level of prostate-specific antigen (PSA). Analysis shows no hematuria or crystalluria. What related finding might you anticipate when you move on to his physical exam?
A) Testicular atrophy
B) Urinary calculi (stones) blocking the urethra
C) Hypospadias
D) Irregular prostatic nodularity
E) Uniformly smooth prostatic enlargement

Accepted Answer

The symptoms described are consistent with benign prostatic hyperplasia (BPH), a common condition in older men characterized by difficulty initiating urine stream, nocturia, and a sensation of incomplete bladder emptying. A uniformly smooth prostatic enlargement on physical examination is a typical finding associated with BPH.

Question 7

A 58-year-old woman with type II diabetes mellitus was diagnosed approximately 1 year ago. Her labs show no improvement in blood glucose control over the ensuing months despite treatment. What test should you order to examine her average blood sugar levels over the past few months? A) Fasting blood glucose B) Two-hour glucose tolerance test C) Hemoglobin D) Hemoglobin A_lc E) Hemoglobin S

Accepted Answer

The correct test to examine average blood sugar levels over the past few months in a patient with diabetes is Hemoglobin A1c (HbA1c), which reflects the average blood glucose levels over the past 2-3 months. The choice listed as "Hemoglobin A_lc" appears to be a typographical error but is intended to represent Hemoglobin A1c.

Question 8

A 14-year-old male soccer player complains of occasional shortness of breath, particularly during practice or games. You decide to initially treat his asthma with a β₂agonist inhaler to be used when symptoms appear. By which mechanism will this agent improve his ability to breathe? A) Bronchodilation via smooth muscle relaxation B) A decrease of pro-inflammatory cells C) Prevention of histamine release D) Inhibition of leukotriene synthesis E) Leukotriene-l receptor antagonism

Accepted Answer

Beta-agonist inhalers work by causing bronchodilation through the relaxation of bronchial smooth muscle, which helps to improve airflow and alleviate symptoms of asthma.

Question 9

Lidocaine, a use-dependent blocker of voltage-gated Na⁺ channels, is an effective antiarrhythmic because its blocking effect becomes greater when: A) The drug is repeatedly used. B) Na⁺channels are activated repeatedly at a high frequency. C) Na⁺ channels are activated repeatedly at a low frequency. D) Na⁺ channels are closed. E) The extracellular Na⁺ concentration is high.

Accepted Answer

Lidocaine's blocking effect on voltage-gated sodium channels increases with higher frequency activation because it preferentially binds to and stabilizes the inactivated state of these channels, which occurs more frequently during rapid firing of action potentials, as seen in arrhythmias.

Question 10

A middle-aged obese man complains of increasing frequency of headaches and worsening visual acuity. Although his headache pain is usually relieved by over-the-counter pain relievers, the discomfort returns after a few hours. An ophthalmoscopic examination reveals bilateral flame hemorrhages and cotton-wool spots. What laboratory measurement would confirm the likely cause of this man's headaches and worsening sight? A) Serum glucose level B) Hemoglobin A_lc C) Toxicology screen including methanol D) Serum vitamin A level E) Blood pressure

Accepted Answer

The symptoms and ophthalmoscopic findings suggest hypertensive retinopathy, which is associated with high blood pressure. Measuring blood pressure would confirm if hypertension is the cause of the headaches and visual changes.

Question 11

A 56-year-old retired schoolteacher presents with progressive dysphagia, substernal pain with eating, and weight loss over the course of 1 year. He has never traveled outside the United States. Barium esophagography reveals esophageal dilation, lack of esophageal peristalsis, and a 'bird's beak' tapering of the distal esophagus. Which of the following is a likely cause of this patient's condition?
A) Achalasia
B) Zenker's diverticulum
C) Barrett's esophagus
D) Chagas disease
E) Increased pressure of the upper esophageal sphincter

Accepted Answer

Achalasia is characterized by esophageal dilation, lack of esophageal peristalsis, and a 'bird's beak' appearance of the distal esophagus on imaging, matching the patient's symptoms and diagnostic findings.

Question 12

A 17-year-old girl comes to see an endocrinologist because of primary amenorrhea. Breast development started several years ago, and she has otherwise been well. On examination breast development and height is in the tenth percentile, but she has no pubic or axillary hair. A pelvic examination reveals a blind vagina. These findings are most consistent with which of the following?
A) Turner's syndrome
B) Hypopituitarism
C) Androgen insensitivity
D) Klinefelter's syndrome
E) Adrenogenital syndrome

Accepted Answer

Androgen insensitivity syndrome is characterized by a female phenotype in an individual with a 46,XY karyotype due to resistance to androgens. This results in normal breast development from estrogen but lack of pubic and axillary hair, primary amenorrhea, and a blind-ending vagina because the individual is genetically male and does not develop a uterus or ovaries.

Question 13

Your 55-year-old female patient suffers from osteoporosis. For treatment you decide to use an antiresorptive agent currently used for treatment of osteoporosis:
A) Increasing parathyroid hormone (PTH) secretion
B) Inhibiting calcitonin release
C) Decreasing the remodeling space of bone
D) Stimulating estrogen synthesis
E) Blocking 1α-hydroxylase activity

Accepted Answer

Decreasing the remodeling space of bone is a mechanism of action for antiresorptive agents used in the treatment of osteoporosis. These agents work by reducing bone turnover, which helps to maintain or increase bone density.

Question 14

A 60-year-old man presents to your office with facial flushing and abdominal cramps and diarrhea. The workup reveals an elevated level of urinary 5-hydroxyindoleacetic acid (5-HIAA), and subsequently, elevated levels of 5-HIAA in a 24-hour urine collection. What is the most likely diagnosis?
A) Zollinger-Ellison syndrome
B) Cushing's syndrome
C) Malignant carcinoid syndrome
D) Vipoma
E) Glucagonoma

Accepted Answer

The elevated level of urinary 5-hydroxyindoleacetic acid (5-HIAA), which is a breakdown product of serotonin, along with symptoms of facial flushing, abdominal cramps, and diarrhea, are characteristic of malignant carcinoid syndrome. This syndrome is caused by carcinoid tumors, which most commonly originate in the gastrointestinal tract.

Question 15

A 30-year-old woman with severe Crohn's disease is taken to surgery for an ileal resection. What nutritional deficiency does this woman risk in the future? A) Folate deficiency B) Niacin deficiency C) Thiamine deficiency D) Iron deficiency E) Vitamin B₁₂deficiency

Accepted Answer

The ileum is the primary site for Vitamin B12 absorption. Resection of the ileum can lead to Vitamin B12 deficiency.

Question 16

A 65-year-old woman with a history of congestive heart failure, osteoarthritis, and hypertension presents with pain and tenderness, which is relieved by food or antacids. Upper endoscopy reveals a gastric ulcer. Her current medications include digoxin, metoprolol, lisinopril, aspirin, and hydrochlorothiazide. Which of her medications is most likely to have contributed to her peptic ulcer disease?
A) Digoxin
B) Metoprolol
C) Lisinopril
D) Aspirin
E) Hydrochlorothiazide

Accepted Answer

Aspirin is known to contribute to peptic ulcer disease due to its ability to inhibit the production of protective gastric mucosal prostaglandins, leading to increased gastric acid secretion and reduced mucosal protection.

Question 17

A 67-year-old man presents with mild dysphagia and throat discomfort that has slowly progressed over the past 5 years. He reports waking up at night choking and regurgitating undigested food. He has been troubled by halitosis and has noticed a small protrusion in his neck over the past year. He denies weight loss or heartburn. Which of the following is most consistent with his symptoms?
A) Achalasia
B) Zenker's diverticulum
C) Gastroesophageal reflux disease
D) Schatzki's ring
E) Esophageal cancer

Accepted Answer

The symptoms described, including dysphagia, regurgitation of undigested food, halitosis, and a neck protrusion, are most consistent with Zenker's diverticulum. This condition involves the formation of a diverticulum, or pouch, in the upper esophagus, which can collect food and lead to the symptoms described.

Question 18

In skeletal muscle during a contraction cycle:
A) Myosin-ATP complex has a high affinity for actin.
B) Tropomyosin binds calcium.
C) The rigor complex is broken by the binding of ADP to myosin.
D) ATP hydrolysis provides the energy required for myosin flexure in the 'hinge regions'.
E) The T tubules take up calcium via an active transport mechanism.

Accepted Answer

ATP hydrolysis provides the energy necessary for the conformational change in myosin, allowing it to "cock" into a position to bind to actin and perform the power stroke. This process involves the flexure or bending in the hinge regions of the myosin molecule.

Question 19

A 47-year-old woman with a longstanding history of heartburn complains of severe heartburn. You make the diagnosis of gastroesophageal reflux disease (GERD). An upper endoscopy study is positive for Barrett's esophagus. Which of the following correctly describes Barrett's esophagus?
A) Replacement of the squamous epithelium of the esophagus with columnar epithelium
B) Replacement of the columnar epithelium of the esophagus with squamous epithelium
C) The presence of moderate-to-high grade dysplasia in the esophagus
D) The presence of low-to-moderate grade dysplasia in the esophagus
E) The presence of any stricture within the esophagus

Accepted Answer

Barrett's esophagus is characterized by the replacement of the normal squamous epithelium of the esophagus with metaplastic columnar epithelium, which occurs as a response to chronic injury from gastroesophageal reflux disease (GERD).

Question 20

Which if the following is true about voltage-gated Na⁺ channels in the axon? A) They remain open as long as the membrane is sufficiently hyperpolarized. B) They remain open as long as the membrane is sufficiently depolarized. C) They remain open for only a short period of time after the cell is sufficiently depolarized. D) They belong to a family of channels that are made of five subunits. E) They have about the same relative permeability ratio (P_Na/P_K) as ACh channels.

Accepted Answer

Voltage-gated Na+ channels open for a short period of time after the cell membrane is sufficiently depolarized, allowing Na+ ions to enter the cell rapidly, contributing to the rising phase of the action potential. They do not remain open as long as the membrane is depolarized or hyperpolarized, are not made of five subunits, and have different permeability ratios compared to ACh channels.

Quiz 1: Introduction

In an elite marathon runner, performance in a marathon race is limited by a number of factors. Among world class marathon runners, which of the following factors is considered to be critical for a high level of performance?

Your 74-year-old male patient suffers from hyperthyroidism. Hyperthyroid individuals characteristically exhibit:

A 58-year-old woman with type II diabetes mellitus was diagnosed approximately 1 year ago. Her labs show no improvement in blood glucose control over the ensuing months despite treatment. What test should you order to examine her average blood sugar levels over the past few months?

A 14-year-old male soccer player complains of occasional shortness of breath, particularly during practice or games. You decide to initially treat his asthma with a β₂agonist inhaler to be used when symptoms appear. By which mechanism will this agent improve his ability to breathe?

Lidocaine, a use-dependent blocker of voltage-gated Na⁺ channels, is an effective antiarrhythmic because its blocking effect becomes greater when:

Your 55-year-old female patient suffers from osteoporosis. For treatment you decide to use an antiresorptive agent currently used for treatment of osteoporosis:

A 60-year-old man presents to your office with facial flushing and abdominal cramps and diarrhea. The workup reveals an elevated level of urinary 5-hydroxyindoleacetic acid (5-HIAA) , and subsequently, elevated levels of 5-HIAA in a 24-hour urine collection. What is the most likely diagnosis?

A 30-year-old woman with severe Crohn's disease is taken to surgery for an ileal resection. What nutritional deficiency does this woman risk in the future?

In skeletal muscle during a contraction cycle:

A 47-year-old woman with a longstanding history of heartburn complains of severe heartburn. You make the diagnosis of gastroesophageal reflux disease (GERD) . An upper endoscopy study is positive for Barrett's esophagus. Which of the following correctly describes Barrett's esophagus?

Which if the following is true about voltage-gated Na⁺ channels in the axon?