GI pouch- Exam 3- Ross Flashcards
By what physiologic mechanisms is the gastric mucosa protected?
bicarbonate and mucus production
What 3 regulatory systems stimulate the stomach’s production of acid
neurocrine: acetylcholine released by **vagal nerve for production of acid
paracrine: local release of hormone: histamine released from stomach wall cells stimulates acid production
endocrine components: gastrin produced by G cells of stomach
increase gastric acid by parietal cells
Digestive enzymes: proteases
-list 3 tyoes
- Pepsinogen/Pepsin
- Trypsinogen
- chymotrypsinogen
Pepsinogen/pepsin=
- produced by chief cells in stomach wall
- cleaved from pepsinogen to pepsin by hcl
- primary cause of mucosal damage in esophageal reflux
Trypsinogen=
a serum protease secreted by pancreas cleaved by enteropeptidase to trypsin
Chymotrypsinogin=
serum protease secreted by pancreas converted into active form by trypsin
Mucosal defense: 3 layer
list 3 layers
- mucus
- surface epithelial cells
- microvascular system
Describe the mucous layer of the mucosal defense
-bicorbonate-phospholipid : physiochemical barrier especially to Hydrogen ions
Describe the surface epthelial cells of the mucosal defense layer
=mucus production, intracellular tight junctions
–>prostaglandins: inhibit acid production, regulate release of bicarb rate limiting production step is controlled by cyclooxygenase (COX-1,COX-2 inflammatory)
Describe the microvascular system of the mucosal defense
-provides subepithelial defense / repair also supplying micronutrients.
B is mucosal defense
3 level barrier= Pre epithelial, epithelial, and subepithelial
-HCO3 (bicarb) coming up from vascular system turning into h20 and co2
Describe the “constant attack” on the GI system
- acid, pepsin, bile acids, pancreatic enzymes, bacteria and drugs
- when this defense breaks down inflammation ensues and ulcer forms
-Gastric acids (Hydrochloric acid )and pepsin destroy gastric and duodenal mucosa. Mucus and bicarbonate ion secretions protect mucosa. Prostaglandins protect mucosa by enhancing mucus and bicarbonate production and by enhancing mucosal blood flow
Gastritis=
- chronic or acute inflammation of gastric mucosa: multiple etiologies
- -dx made by endoscopy and is histological
PUD=
- both gastric and duodenal is a more chronic illness characterized by the formation of recurrent ulcers (>5mm in size) in the stomach an proximal duodenum
- -definitive dx made by upper GI or endoscopy
Dyspepsia=
continuous or recurrent upper abdominal pain it’s a symptom not a pathophysiologic condition
Gastritis- is NOT to be interchanged with _____
dyspepsia
Sx of Gastritis
-acute vs chronic epigastric pain (dyspepsia)
-Generally non-erosive
inflammatory cell infiltrate
-Infectious: usually acute: H.Pylori, CMV
- Granulomatous: as in Chron’s dz
- If involving astral cells can cause **pernicious anemia
-**endoscopic sub epithelial hemorrhages: no major bleeding as no art/vein in mucosa
Infectious Gastritis
-Bacterial- rapidly progressive, rare, life-threatening
-Viral- CMV(cytomegalovirus) in the immunocompromised/
immunosuppressed patient
- Fungal- Candida in immunocompromised patients
- Parasitic- among others -Anisakis marina from raw fish or sushi can become embedded in gastric mucosa
Erosive and Hemorrhagic Gastritis: “stress gastritis:”
- MC caused by?
- endoscopic findings?
Most commonly caused by: Stress Meds Alcohol Portal hypertension
Endoscopic findings:
- Subepithelial hemorrhages
- Petechiae
- Erosions
Stress gastritis:
erosions may occur rapidly following?
- Mechanical ventilation*
- Coagulopathy*
- Major physical or thermal trauma
- Shock
- Sepsis
- Head injury
- Hepatic, renal or multiorgan failure
**very ill Pts in the ICU
Peptic ulcer disease (PUD)=
-etiology?
- etiology 12% males usually due to alcoholism
- 10% fem usually due to NSAIDs
- 15,000 deaths
PUD= disruption of mucosal integrity of stomach or duo leading through to the muscularis mucosa into deeper layers to a local defect due to active inflammation
Ulcer is defined as ____
is a breakdown in the mucosal surface, through the muscularis mucosa into deeper layers to a local defect due to active inflammation.
alcohol
->5 mm in size
H. Pylori=
-produces?
-Helix shaped curved gram neg rod with flagella that penetrate through mucosa of stomach to a less acidic environment
-produces ammonia which is cytotoxic to lining cells of stomach
and also a focus of inflammatory response
-thereby decreasing the protective layer and harming the epithelial cells (added by pepsin)
____% of those infected with H pylori are asymptomatic
80%, (most ppl dont develop ulcers)
H. Pylori testing (list methods)
- serum antibody: IgG levels : variable accuracy depending on lab vs home commercial test
- urea breath test: Best established test ** KNOW
- stool antigen : simple and accurate less expensive
- -With noninvasive Testing
- -Discontinue PPIs 7-14 days prior to testing by breath or feces
-Endoscopy- not indicated specifically but if being performed for another reason, biopsy can be obtained
H. pylori: testing is indicated for? (3 things)
- Active or past history of PUD
- Gastric MALToma (mucosa-associated lymphoid tissue lymphoma)
- Family history of gastric carcinoma (especially if Asian descent)
Peptic Ulcer Presentation:
-Duodenal? (sx)
- Burning pain 1-3 hours after meals, relieved by food
- Epigastric pain (vague discomfort, cramping, hunger pangs)
- Nocturnal pain with early morning awakening
- usually within 3cm of pylorus
Peptic Ulcer Presentation:
Gastric? (Sx)
- Not common to see post-prandial epigastric pain
- Weight loss
- later in life peak 6th decade
- **associated with malignancy