Human Digestive System Case Studies (for undergraduate college students)

Disclaimer: These hypothetical Digestive System Case Studies were developed and written by Nancy Palmer-Shevlin MD, (for use in undergraduate Human Physiology courses), to assist students in applying concepts learned in lectures and textbooks.They are not intended as Medical training or for self-diagnosis, or diagnoses of others. They are intended for educational purposes only.The photos of people were obtained from Clip Art images and are not photos of real patients, and no personal or confidential medical information of any real patient are included.

Transcript

1. DIGESTIVE SYSTEM CASES Disclaimer: These hypothetical Digestive System Case Studies were developed and written by Nancy Palmer-Shevlin MD, (for use in undergraduate Human Physiology courses), to assist students in applying concepts learned in lectures and textbooks.They are not intended as Medical training or for self-diagnosis, or diagnoses of others. They are intended for educational purposes only.The photos of people were obtained from Clip Art images and are not photos of real patients, and no personal or confidential medical information of any real patient are included.
2. • Jane, a 20 year old college honor student and athlete, developed pharyngitis and fever of 101 degrees F, of 3 days duration. The nurse at the Student Health Center, noted her tonsils were erythematous and edematous. She performed a nasal screening test for Sars-coV-2, then did a Strep test, and it was positive. Jane was given a 10-day prescription for amoxicillin and after 6 days on antibiotics developed diarrhea. Her covid screen came back negative. 1.Amoxicillin is in what class of antibiotics? 2.What is the mechanism of action of amoxacillin? 3.What might have caused her diarrhea, given this scenario? 4.How could the diarrhea have been prevented?
3. How Selected Antibiotics Work
4. Patient 1, cont’d: Some antibiotics may cause diarrhea because they may kill the mutualistic bacteria (ex. Lactobacillus acidophilus) and yeast (Saccharomyces boulardii) in your intestine, while they are killing bacterial pathogens causing disease in your body (in this case Streptococcus,group A.) Lactobacillus acidophilus is the most abundant mutualistic bacterium in our intestines. Probiotics and yogurt containing live cultures of L. acidophilus prevent diahrrea caused by some antibiotics. Source: 2021 Probiotic Supplements Guide: What To Look Forhttps://ushealthreport.org/probiotics- guide/?gclid=EAIaIQobChMInsGn_Kqd8gIViuazCh3FVAezEAAYAiAAEgJ7d_D_BwE Characteristics of Effective Probiotics •Able to survive the passage through the digestive system. •Able to attach to the intestinal epithelia and colonise. •Able to maintain good viability. •Able to utilise the nutrients and substrates in a normal diet. •Non pathogenic and non toxic. •Source: 2021 Probiotic Supplements Guide
5. PERSON 2: Bob Bob is a nineteen- year old college freshman who was nauseous for the past two days. He assumed it was a stomach virus then proceeded to his class to give a scheduled presentation. He became diaphoretic and had chills and asked if he could reschedule his presentation. He returned to his dorm and became more nauseous,vomited and had diarrhea . He developed a fever of 102 F and severe periumbilical pain which started in the R lower quadrant of his abdomen. It became so severe that his roomate called 911. In the ER his white blood cell count was 20,000. (n=5-10,000).He has no history of renal calculi, and urinalysis was normal. The ER physician performed a physical exam. His lungs were clear on auscultation, his heart rate was 100bpm. On exam there did not appear to be splenomegaly or hepatomegaly. Abdominal exam is remarkable for rebound tenderness in the RLQ and in the periumbilical region, pain on percussion and guarding. 1.List the possible conditions that you suspect might be causing Bobs symptoms? 2.What organ or structure is located in the R Lower quadrant of the average abdomen?
6. Person 2: BOB,cont’d A CT scan of the abdomen with contrast was performed. An inflamed appendix , measuring approx. 8 mm in diameter, with appendiceal wall thickening, and enhancement after contrast infusion, was visualized. Bob was prepped for surgery and an emergency appendectomy was performed, after IV antibiotics were initiated.Following surgical excision, the appendix and surrounding tissue were sent to the Pathologist for biopsy. Microscopic images of the tissue is featured in the two lower images. 1.Describe the microscopic features of the tissue. Visually compare the tissue with the photomicrographs of thehuman appendix in your textbooks. List the similarities and differences. What is the significance of this? 2.What ,if any, is the purpose of the human appendix? 3.Why did Parker refer to it as a “safe house”? 4.What structure did Darwin theorize the primate appendix evolved from? 5.What causes appendicitis? 6. What are some of the early signs and symptoms of appendicitis?
7. PERSON 3: DIANE Diane, a twenty-two year old medical student in the Honors Program , had been experiencing occasional abdominal discomfort after meals. The discomfort became severe tonight about an hour after eating a ice cream sundae with her friends, none of whom became ill. Jan spent much of that night in pain-she had diffuse abdominal cramps and diarrhea and also felt nauseous.She did not vomit. She went to theout-patient clinic the next morning and saw her physician. She told the physician that on most evenings she cooked for herself, usually preparing traditional cuisine, and that she seldom experienced any discomfort after eating at home. She only experienced discomfort after dining out, especially, it seemed, after eating cheese or ice cream. Diane suspected that her symptoms may possibly be due to food poisoning, food allergy, or lactose intolerance. Since her symptoms only seem to occur with dairy products, and none of her friends eating the same foods at the same time, became ill, she suspects she has lactose intolerance. A recent Gynecologic exam was normal, negative pregnancy test, and no history of Pelvic Inflammatory Disease.She had a history of appendectomy in 2016 with no sequelae.No history of other GI disease, no H/O UTI or renal calculi. Her physical exam today revealed bloating, increased bowel sounds, slight tenderness on palpation, no rebound sign, no obturator sign , mild flatulence. Laboratory test showed WBC count of 5,500; no anemia,all other blood tests were WNL. normal urinalysis. Her physician ordered a Hydrogen Breath Test which was positive. 1.How does the Hydrogen Breath test assist in diagnosing lactose intolerance? 2.Describe the pathophysiology of lactose intolerance. Include the genetics and epigenetics of Lactose Intolerance. 3. What is the medical definition of Lactase persistence? What are the genetics that allow lactase persistence? 4.What is a Single Nucleotide Polymorphism? 5.What is the global prevalence of Lactose Intolerance? 6.Explain why it is more prevalent in some geographical areas. 7.What is the treatment for Lactose Intolerance?
8. • Source: SlidePlayer
9. According to American Academy of Family Physicians https://www.aafp.org/afp/2002/0501/p1845.html LACTOSE INTOLERANCE AND LACTOSE PERSISTENCE “Persons with lactose intolerance are unable to digest significant amounts of lactose because of a genetically inadequate amount of the enzyme lactase. Common symptoms include abdominal pain and bloating, excessive flatus, and watery stool following the ingestion of foods containing lactose. Lactose intolerance is generally a lifelong inherited condition but can be a temporary result of an infection or other insult to the jejunal mucosa. The lactase enzyme is located in the brush border (microvilli) of the small intestine enterocyte. The enzyme splits and hydrolyzes dietary lactose into glucose and galactose for transport across the cell membrane. The enzyme activity and the transit time of lactose through the jejunum mucosa are important for proper absorption. If lactase enzymes are absent or deficient (hypolactasia), unabsorbed sugars osmotically attract fluid into the bowel lumen Concerning evolutionary genetics, LP is one of the strongest examples of positive selection found in the human genome.
10. Lactose intolerance is mostly due to your genes “While the ability to produce the lactase enzyme persists into adulthood in only about 35% of adults worldwide, this proportion varies widely among ethnic groups. In the U.S., the proportion of lactose-tolerant people is about 64%, reflecting the mixture of ethnic groups that populate the country.” “Specific genetic changes – known as single-nucleotide polymorphisms, SNPs – conveying lactase-persistence, arose independently in various populations around the same time as their domestication of dairy animals. None of these SNPs are in the lactase gene itself, but instead are in a nearby region of the DNA that control its activity. Scientists have been trying to figure out how these changes exert their influence over this gene’s behavior.” ADDITIONAL REFERENCE:https://www.ncbi.nlm.nih.gov/pmc/articles /PMC7551416/ This SNP, located 13910 base pairs in front of the lactase gene, has the DNA base pair C:G replaced by a T:A. The mutation apparently prevents the DNA from being methylated at this site, and so the lactase gene stays active. http://www.evo-ed.com, CC BY-NC (This site has an excellent presentation on Lactose Intolerance)
11. PERSON 4: HAROLD Harold, a forty-six year old executive, had recently been waking up in the middle of the night with abdominal pain in the midepigastric region. The pain was described as intermittent, burning and he said it did not radiate to his back. This occurred several nights per week. He was also experiencing occasional discomfort in the late afternoon after eating spicey food. Harold decided to schedule an appointment with his Family Practice Physician,who has taken care of Harold and his family for many years. His physician listened as Harold described his symptoms and then asked Harold some questions. She noted that Harold's appetite had suffered as a result of the pain he was experiencing and as a result of concern that what he was eating may be responsible for his pain. Otherwise, Harold seemed fine. He says that he does not smoke or drink alcohol.No vomiting, constipation or diarrhea. His Physical Exam was remarkable for discomfort in the midepigastric region on palpation.No rebound tenderness was noted. All of Harolds blood tests were within normal range;he did not have anemia.There was no occult blood in his stool sample. His physician referred him to a Gastroenterologist.
12. The Gastroenterologist ordered an ultrasound of the abdomen and the gallbladder and all visualized structures appeared normal.No stones, fluid, or thickening of the gallbladder wall were visualized. The barium contrast radiography showed pocket of barium filling the ulcer crater. Since so many peptic ulcers are caused by a certain bacteria, the stool antigen test and urea breath test were performed. 1. Which bacteria is the most frequent cause of peptic ulcer disease? .In Harold ,these tests were inconclusive. Therefore his physician referred An endoscopy was performed at an outpatient surgi-center later that week. During the procedure, a long, thin tube was inserted into Harold's mouth and directed into his digestive tract. The end of the tube was equipped with a light source and a small camera which allowed the doctor to observe the lining of Harold's stomach. The endoscope was also equipped with a small claw-like structure that the doctor could use in order to obtain a small tissue sample from the lining of Harold's stomach. The large erosion in the fundus of Harolds stomach is shown in the photo on the Left.The physician took a sample of tissue for histology and cultures. 1.What disease does Harold have? 2. What causes this disease? 3. What is the treatment for this?
13. Harold was relieved that his biopsy was negative for cancer. However,it showed a high amount of severe inflammation.His cultures were positive for Helicobacter pylori. His physician treated him with antibiotics, medication to block histamine, and medication to block production of stomach acid. 1.What are the risk factors for Peptic Ulcer Disease? 2. What is the difference between a peptic ulcer and a duodenal ulcer? 3.What % of patients with ulcers are positive for H.pylori? 4.What is the role of histamine in gastric ulcer disease? Sources:Diagram on L from Alamy, stock photos ;Diagram on R https://publichealth.arizona.edu/outreach/health- literacy-awareness/hpylori/transmission
14. • Source: hopkinsmedicine.org
15. PERSON 5: MARY G. Mary G is a 42 year old , slightly obese woman who works as a Microbiologist.She presents to the office with diffuse abdominal pain of 3 months duration. She has lost 12 pounds over the last 4 months, due to illness and reports loss of appetite and diarrhea approx. three times per week. Her pain becomes worse after a fatty meal.She has flatus.She has no history of alcohol abuse and has family history of small bowel disease. On initial examination, vital signs are normal, but there is tenderness in the R upper quadrant of her abdomen, radiating to the R side of her back. There is no jaundice. Recent exam by her regular gynecologist is normal. Pregnancy test is negative and she still has regular menstrual periods. She has no history of renal calculi, renal or GI disease and has had no previous surgery. Initial laboratory evaluation shows slight elevation in liver function tests, which include AST, ALT, alkaline phosphatase. Her WBC count is normal. Tests for hepatitis A,B,C were negative. Total cholesterol and LDL-cholesterol levels were elevated. All other blood assays were in normal range. Urinalysis was normal. Previous stool cultures for pathogens reported normal flora. Her Primary Care Physician ordered barium contrast radiography of the upper GI tract and an abdominal ultrasound. 1.What conditions might cause elevation in liver enzymes? 2.What organs/structures are in the R upper quadrant of abdomen, and right upper back?
16. Person 5,Continued: The barium contrast radiography, (image on the LEFT, above) is normal, except for the incidental finding,at the tip of the arrow, noticed by an astute Medical Student. The results of the abdominal ultrasound, shown on the R above, confirmed the physicians suspected diagnosis. 1.What are the findings on the radiograph? 2. What are the findings on the ultrasound? 3.What is the diagnosis based on these findings?
17. . 1.What is Cholecystitis? 2.List the causes of cholecystitis. 3.What is the most common cause of cholecystitis? 4.What causes gallstones to form? 5.How can cholecystitis be prevented? How can it be treated? 6.What are the complications of cholecystitis?