THE INTEGRATED TEACHING APPROACH

Introduction to the Gastrointestinal System

Khaled Jadallah, MD

Assistant Professor of Medicine

Gastroenterology, Hepatology & Nutrition

Department of Internal Medicine

Why the Integrated Gastrointestinal Study Module?

• More organized than classical teaching

• Easier to comprehend

• More clinically oriented

• More interesting and stimulating

Overview• Dramatic growth of knowledge in GI over the

last 2-3 decades.

• Better understanding of the biology,

biochemistry and physiology of the GUT

• New insights in the pathophysiology of different

GI diseases

• Breakthrough in the diagnostic and therapeutic

tools and procedures in gastrointestinal

diseases

An Endoscopic and Radiologic/Anatomic Journey through the

Gastrointestinal Channel

                                                             

             

            

      

The Larynx

                                                             

             

            

      

The Esophagus

                                                    

                      

                                                             

             

            

      

The cardias or EGJ

                                                             

             

            

      

The Gastric Fundus

                                                             

             

                                                             

             

            

      

The Gastric Corpus

                                                            

             

                                                             

             

            

      

The Gastric Corpus

                                                             

             

            

      

The Angulus

                                                             

             

            

      

The Gastric Antrum

                                                             

             

                                                             

             

            

      

The Pyloric Canal

                                                             

             

            

      

The Duodenal Bulb

                                                            

              

                                                            

             

            

      

The Papilla of Vater

                                                             

             

            

      

The Descending Duodenum

                                                             

             

            

      

The Jejunum

                                                              

            

                                                             

             

            

      

The Terminal Ileum

                                                         

                 

                                                             

             

            

      

The Ileo-Cecal Valve

                                                           

               

                                                             

             

            

      

The Appendiceal Orifice

                                                            

              

                                                             

             

            

      

The Transverse Colon

                                                                 

         

                                                             

             

            

      

The Descending Colon

                                                             

             

                                                             

             

            

      

The Rectum

                                                             

             

                                                             

             

            

      

The Anus

                                  

                  

What is this???

Case 1A 45-year-old man has had dysphagia of increasing severity over the past year. He has recently lost 3 Kg. Upper endoscopy is normal except for some resistance to passage of the endoscope at the esophagogastric junction.

What do you think is going on??

Case 1 (cont’d)

• Questions to ask:– Is the dysphagia for solids only or for both

solids and liquids??– Is it a “transfer” dysphagia or “transit”

dysphagia??– What further investigations should we do??

• The diagnosis is: Esophageal achalasia (lack of peristalsis, high pressure LES and incomplete relaxation of LES on swallowing

• Manometry is diagnostic

Anatomo-Physiologic Basis of Dysphagia

– The process of swallowing depends on the voluntary action of the orophayngeal striated muscles and the involuntary action of the esophageal smooth muscles

– Dysphagia secondary to oropharyngeal problems (neurologic or muscular) is called TRANSFER dysphagia

– Dysphagia secondary to esophageal problems (Anatomic obstruction or dysmotility) is called TRANSIT dysphagia

Case 2

A 57-year-old man presents with a 3-month history of epigastric pain and voluminous, foul smelling diarrhea. The diarrhea persists despite fasting. Nasogastric suction dramatically decreases stool output.

What’s your diagnosis??

Case 2 (cont’d)

• This is a case of Zollinger-Ellison Syndrome (Gastrinoma)• The pathophysiology of ZES is explained as follows:

– The pain is caused by ulcerations of acid hypersecretion and decreased cytoprotective effect of pancreatic and gastric sodium bicarbonate

– The diarrhea is caused by the increased volume of acid and the irritation of the GIT mucosa (secretory diarrhea)

– The steatorrhea is provoked mainly by inactivation of pancreatic enzymes and defective micelle formation

– These symptoms can be effectively treated by proton pump inhibitirs (e.g. omeprazole, lansoprazole, esomeprazole, ….) which decrease the acid secretion

Case 3

• A 52-year-old obese woman presents with a 4-day history of right upper quadrant pain, associated with nausea and jaundice. The patient also reports dark, tea-colored urine and pale stools.

What is the most likely diagnosis??

Case 3 (cont’d)

• The antomo-pathology and physiopathology of bilairy pain and jaundice– Biliary pain is caused by obstruction of the bile ducts, especially

the CBD. It’s constant and not colicky– Jaundice associated with dark urine (bilirubinuria) and light

stools is mostly secondary to obstruction to the flow of bile. – Direct or conjugated bilirubin, but not indirect bilirubin, is water

soluble and therefore can be filtrated in the kidneys

• The diagnosis is: Choledocholithiasis (stone impacted in the CBD)

• The treatment?? ERCP with stone extraction followed by cholecystectomy

Case 4• A 75-year-old woman with a longstanding history

of osteoarthritis and diclofenac (Voltaren) use presents to the ER with hematemesis. EGD is performed and showed multiple ulcers in the antrum.

What is the biochemical/physiologic basis of this patient’s ulcers??

                         

  

Case 4 (cont’d)• Non Steroidal Antinflammatory Drugs (NSAIDs)

such as diclofenac inhibit both cycloxygenase-1 (COX-1) and COX-2 enzymes.

• COX-1 is enzyme responsible for prostaglandin (PG) production. PG has a cytoprotective effect on the gastric mucosa

• COX-2 specific (or COX-1 sparing) NSAIDs (such as celecoxib and rofecoxib) have lower PG inhibition and therefore lower ulceration rate than non selective NSAIDs

• A synthetic PG such as MISOPROSTOL can be used along with NSAIDS to decrease the ulceration rate

Take-Home Points

• An integrated approach to basic sciences is more effective than classic teaching

• Translational basic sciences bridges the gap between basic sciences and patient care

• Translational basic sciences can transfer clinical insights into hypothesis that can be tested and validated in the basic research laboratory

Take-Home Points (cont’d)

• The integrated teaching approach allows easier application of knowledge and basic research into clinical practice

• In the future, multidisciplinary teaching laboratories/seminar rooms will provide venue to teach laboratory sciences such as histology, microbiology, and pathology in un updated clinical context