GI physiology (digestion, absorption, motility) Practice Questions

Question 1

A 25-year-old male presents to his primary care physician for fatigue, abdominal pain, diarrhea, and weight loss. He states that this issue has occurred throughout his life but seems to “flare up” on occasion. He states that his GI pain is relieved with defecation, and his stools are frequent, large, and particularly foul-smelling. The patient has a past medical history of an ACL tear, as well as a car accident that resulted in the patient needing a transfusion and epinephrine to treat transfusion anaphylaxis. His current medications include vitamin D and ibuprofen. He recently returned from a camping trip in the eastern United States. He states that on the trip they cooked packed meats over an open fire and obtained water from local streams. His temperature is 99.5°F (37.5°C), blood pressure is 120/77 mmHg, pulse is 70/min, respirations are 11/min, and oxygen saturation is 98% on room air. Physical exam reveals poor motor control and an ataxic gait on neurologic exam. Cardiac and pulmonary exams are within normal limits. Laboratory studies are ordered and return as below:

Hemoglobin: 9.0 g/dL
Hematocrit: 25%
Haptoglobin: 12 mg/dL
Leukocyte count: 7,500 cells/mm^3 with normal differential
Platelet count: 255,000/mm^3

Serum:
Na+: 140 mEq/L
Cl-: 102 mEq/L
K+: 5.0 mEq/L
HCO3-: 24 mEq/L
BUN: 24 mg/dL
Glucose: 82 mg/dL
Creatinine: 1.0 mg/dL
Ca2+: 9.0 mg/dL
LDH: 457 U/L
AST: 11 U/L
ALT: 11 U/L

Radiography is ordered which reveals a stress fracture in the patient’s left tibia. Which of the following is the best confirmatory test for this patient’s condition?

Accepted Answer

Vitamin E level

Answer

Stool ELISA

Answer

Vitamin B12 and folate level

Answer

Bowel wall biopsy

Answer

Iron studies

Question 2

A 37-year-old man with Crohn disease is admitted to the hospital because of acute small bowel obstruction. Endoscopy shows a stricture in the terminal ileum. The ileum is surgically resected after endoscopic balloon dilatation fails to relieve the obstruction. Three years later, he returns for a follow-up examination. He takes no medications. This patient is most likely to have which of the following physical exam findings?

Accepted Answer

Weakness and ataxia

Answer

Dry skin and keratomalacia

Answer

Hyperreflexia with tetany

Answer

Gingival swelling and bleeding

Answer

Pallor with koilonychia

Question 3

A 21-year-old woman presents to the clinic complaining of fatigue for the past 2 weeks. She reports that it is difficult for her to do strenuous tasks such as lifting heavy boxes at the bar she works at. She denies any precipitating factors, weight changes, nail changes, dry skin, chest pain, abdominal pain, or urinary changes. She is currently trying out a vegetarian diet for weight loss and overall wellness. Besides heavier than usual periods, the patient is otherwise healthy with no significant medical history. A physical examination demonstrates conjunctival pallor. Where in the gastrointestinal system is the most likely mineral that is deficient in the patient absorbed?

Accepted Answer

Duodenum

Answer

Large intestine

Answer

Ileum

Answer

Jejunum

Answer

Stomach

Question 4

A 42-year-old man comes to the physician because of severe epigastric pain for a week. The pain is constant and he describes it as 6 out of 10 in intensity. The pain radiates to his back and is worse after meals. He has had several episodes of nausea and vomiting during this period. He has taken ibuprofen for multiple similar episodes of pain during the past 6 months. He also has had a 5.4-kg (12-lb) weight loss over the past 4 months. He has a 12-year history of drinking 3 to 4 pints of rum daily. He has been hospitalized three times for severe abdominal pain in the past 3 years. He appears ill. His temperature is 37°C (98.6°F), pulse is 87/min, and blood pressure is 110/70 mm Hg. There is severe epigastric tenderness to palpation. Bowel sounds are normal. Cardiopulmonary examination shows no abnormalities. Laboratory studies show:
Hemoglobin 13.6 g/dL
Leukocyte count 7,800/mm3
Serum
Glucose 106 mg/dL
Creatinine 1.1 mg/dL
Amylase 150 U/L
A CT of the abdomen is shown. Which of the following is the most appropriate long-term management for this patient?

Accepted Answer

Pancreatic enzyme therapy

Answer

Whipple procedure

Answer

Endoscopic stent placement

Answer

Celiac ganglion block

Answer

Gluten-free diet

Question 5

An 82-year-old woman presents with 2 months of foul-smelling, greasy diarrhea. She says that she also has felt very tired recently and has had some associated bloating and flatus. She denies any recent abdominal pain, nausea, melena, hematochezia, or vomiting. She also denies any history of recent travel and states that her home has city water. Which of the following tests would be most appropriate to initially work up the most likely diagnosis in this patient?

Accepted Answer

Fecal fat test

Answer

Tissue transglutaminase antibody test

Answer

Stool O&P

Answer

Stool guaiac test

Answer

CT of the abdomen with oral contrast

Question 6

A 31-year-old woman visits the clinic with chronic diarrhea on most days for the past four months. She also complains of lower abdominal discomfort and cramping, which is relieved by episodes of diarrhea. She denies any recent change in her weight. Bowel movements are preceded by a sensation of urgency, associated with mucus discharge, and followed by a feeling of incomplete evacuation. The patient went camping several months earlier, and another member of her camping party fell ill recently. Her temperature is 37° C (98.6° F), respiratory rate is 15/min, pulse is 67/min, and blood pressure is 122/98 mm Hg. Her physical examination is unremarkable. A routine stool examination is within normal limits and blood test results show:
Hb%   13 gm/dL
Total count (WBC):   11,000/mm3
Differential count:    
  Neutrophils: 70%
  Lymphocytes: 25%
  Monocytes: 5%
ESR:   10 mm/hr
What is the most likely diagnosis?

Accepted Answer

Irritable bowel syndrome

Answer

Giardiasis

Answer

Ulcerative colitis

Answer

Crohn’s disease

Answer

Laxative abuse

Question 7

A 54-year-old man presents to his primary care physician with a 2-month-history of diarrhea. He says that he feels the urge to defecate 3-4 times per day and that his stools have changed in character since the diarrhea began. Specifically, they now float, stick to the side of the toilet bowl, and smell extremely foul. His past medical history is significant for several episodes of acute pancreatitis secondary to excessive alcohol consumption. His symptoms are found to be due to a deficiency in an enzyme. Which of the following enzymes is most likely deficient in this patient?

Accepted Answer

Lipase

Answer

Enterokinase

Answer

Amylase

Answer

Colipase

Answer

Chymotrypsin

Question 8

A 24-year-old man comes to the physician with a 2-day history of fever, crampy abdominal pain, and blood-tinged diarrhea. He recently returned from a trip to Mexico. His temperature is 38.2°C (100.8°F). Abdominal examination shows diffuse tenderness to palpation; bowel sounds are hyperactive. Stool cultures grow nonlactose fermenting, oxidase-negative, gram-negative rods that do not produce hydrogen sulfide on triple sugar iron agar. Which of the following processes is most likely involved in the pathogenesis of this patient's condition?

Accepted Answer

Inhibition of host cytoskeleton organization

Answer

Dissemination via bloodstream

Answer

Overactivation of adenylate cyclase

Answer

Flagella-mediated gut colonization

Answer

Invasion of colonic microfold cells

Question 9

Which neurotransmitter primarily mediates slow synaptic transmission in the enteric nervous system?

Accepted Answer

Nitric oxide

Answer

Substance P

Answer

Serotonin

Answer

Acetylcholine

Question 10

A 54-year-old man comes to the physician because of diarrhea that has become progressively worse over the past 4 months. He currently has 4–6 episodes of foul-smelling stools per day. Over the past 3 months, he has had fatigue and a 5-kg (11-lb) weight loss. He returned from Bangladesh 6 months ago after a year-long business assignment. He has osteoarthritis and hypertension. Current medications include amlodipine and naproxen. He appears pale and malnourished. His temperature is 37.3°C (99.1°F), pulse is 76/min, and blood pressure is 140/86 mm Hg. Examination shows pale conjunctivae and dry mucous membranes. Angular stomatitis and glossitis are present. The abdomen is distended but soft and nontender. Rectal examination shows no abnormalities. Laboratory studies show:
Hemoglobin 8.9 g/dL
Leukocyte count 4100/mm3
Platelet count 160,000/mm3
Mean corpuscular volume 110 μm3
Serum
Na+ 133 mEq/L
Cl- 98 mEq/l
K+ 3.3 mEq/L
Creatinine 1.1 mg/dL
IgA 250 mg/dL
Anti-tissue transglutaminase, IgA negative
Stool culture and studies for ova and parasites are negative. Test of the stool for occult blood is negative. Fecal fat content is 22 g/day (N < 7). Fecal lactoferrin is negative and elastase is within normal limits. Which of the following is the most appropriate next step in diagnosis?

Accepted Answer

PAS-stained biopsy of small bowel

Answer

CT scan of the abdomen

Answer

IgG against deamidated gliadin peptide

Answer

Schilling test

Answer

Enteroscopy

GI physiology (digestion, absorption, motility)

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Gastrointestinal hormones

Salivary secretion and function

Gastric secretion regulation

Pancreatic exocrine function

Bile production and secretion

Carbohydrate digestion and absorption

Protein digestion and absorption

Lipid digestion and absorption

Water and electrolyte handling in GI tract

Intestinal barrier function

GI motility patterns and regulation

Defecation reflex

Gut microbiome interactions

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