45 Questions
What is the primary mechanism of acid secretion in the gastric mucosa?
Neurotransmitter-mediated increase in histamine release from ECL cells
Which of the following GI pathologies is characterized by narrowing of the pyloric canal?
Pyloric stenosis
What is the primary cause of parietal pain in the gastrointestinal tract?
Mediators of the inflammatory response stimulating afferent nociceptor fibers
What is the primary function of the liver in the GI tract?
Production of bile salts for fat emulsification
Which of the following is NOT a pathology related to gastric mucosal function?
Gastroesophageal reflux disease
Which of the following is a common symptom of nausea?
Hypersalivation
What is the primary site of nutrient absorption in the GI tract?
Small intestine
What is the term for the vomiting of bright red blood in the absence of nausea or retching?
Projectile vomiting
Which of the following is a type of GI bleeding that can be detected with tests for heme?
Occult bleeding
What is the primary function of the esophagus?
Conduit for food and mechanical digestion
Which of the following mechanisms of pathology is most likely to occur in the esophagus?
All of the above
What is the term for the narrowing or stricture of an area in the gastrointestinal tract?
Stenosis
Which of the following is a type of GI disorder that can cause esophageal inflammation or esophagitis?
Gastroesophageal reflux disease (GERD)
What is the term for the passage of bright red blood per rectum?
BRBPR
Which of the following is a type of GI disorder that can cause abnormalities of movement in the esophagus?
Esophageal dysmotility
What is the primary mechanism by which a fetus absorbs amniotic fluid during in utero development?
Through the fetal GI tract, then into the bloodstream
What is the primary risk associated with Tracheo-Esophageal Fistula in newborns?
Aspiration pneumonia
What is the general process that causes Esophageal Stricture?
Mucosal inflammation and scarring
What is the inherent physiological problem in Esophageal Achalasia?
Neurologic problem
What is the most common cause of Esophagitis?
Regurgitant stomach acid
What is the pathophysiological mechanism underlying Reflux Esophagitis?
All of the above
What is the characteristic of Barrett's Esophagus?
Growth of columnar epithelium with goblet cells present
What is the risk associated with Barrett's Esophagus?
Increased risk of esophageal cancer
What is the primary cause of VACTERL syndrome?
Unknown
What is the treatment for Esophageal Stricture?
Esophageal dilation
What is the primary function of mucous cells in the gastric glands?
Produce mucus
Which phase of HCl production is stimulated by the sight, smell, or taste of food?
Cephalic phase
What is the primary mechanism by which H. pylori flourishes in the stomach?
Production of ammonia from urea
What is the result of a decrease in mucus production in the stomach?
Increased risk of peptic ulcer disease
What is the term for a gastrin-secreting tumor that can occur in the pancreas or duodenum?
Gastrinoma
What is the effect of somatostatin on HCl production?
Inhibits acid release
What is the primary mechanism by which anticholinergics decrease HCl production?
Inhibition of acetylcholine release
What is the term for the clinical combination of duodenal ulcers and a pancreatic gastrin tumor?
Zollinger-Ellison syndrome
What is the effect of H. pylori infection on the stomach when the cardia is significantly affected?
Decreased mucus production
What is the approximate percentage of adults over 50 in developed countries who are infected with H. pylori?
50%
What is the most common cause of gastroparesis?
Neuropathy
What is the result of bacterial overgrowth of retained gastric contents in gastroparesis?
Malabsorption and diarrhea
What is the term for a mass of hardened, undigested food or other material trapped in the digestive system?
Bezoar
What is the treatment for pyloric obstruction due to inflammatory disorders?
Gastric drainage and IV fluid and electrolytes
What is the classic symptom of pyloric stenosis in babies?
Projectile vomiting
What is the result of un-treated pyloric stenosis on blood volume?
Decreases
What is the kidney's response to decreased blood volume and sodium content in pyloric stenosis?
Increased aldosterone release
What is the physical sign of pyloric stenosis?
A mass in the epigastric region
What is the treatment for pyloric stenosis?
Surgery
What is the result of increased pH in pyloric stenosis?
Metabolic alkalosis
Study Notes
GI Pathophysiology
- Normal GI tract physiology:
- Neural control of GI function
- Processing of food through the GI tract
- GI blood flow
- Secretory functions of the mouth, stomach, pancreas, liver, and intestines
- Digestion and absorption in the GI tract
Gastric Mucosal Mechanisms
- Gastric acid secretion:
- Mediated by parietal cells
- Stimulated by acetylcholine, histamine, and gastrin
- Inhibited by somatostatin
- Mucosal protection:
- Mucous cells produce mucus to protect against acidic pH
- Decreased mucus production can lead to peptic ulcer disease
Clinical Manifestations of GI Pathology
- Anorexia:
- Loss of appetite
- Lack of desire to eat despite physiologic stimuli
- Nausea:
- Subjective experience associated with various conditions
- Common symptoms include hypersalivation and tachycardia
- Vomiting:
- Forceful emptying of stomach and intestinal contents through the mouth
- Can lead to fluid, electrolyte, and acid-base disturbances
- Abdominal pain:
- Can be caused by stretching, inflammation, or ischemia
- Can be parietal (somatic), visceral, or referred pain
- GI bleeding:
- Upper GI bleeding: from esophagus, stomach, or duodenum
- Lower GI bleeding: from jejunum, ileum, colon, or rectum
- Clinical manifestations: melena, hematochezia, or bright red blood in stool
Esophagus Pathologies
- Stenosis:
- Narrowing or stricture of the esophagus
- Causes: chronic inflammation, genetic predisposition, and iatrogenic injury
- Regurgitation or insufficiency:
- GERD: can cause esophageal inflammation and esophagitis
- Abnormalities of movement: esophageal dysmotility
- Inflammation/trauma:
- Esophagitis: inflammation of the esophagus
- Barrett's esophagus: premalignant lesion with increased risk of esophageal cancer
- Malory-Weiss tear: longitudinal tear in the esophageal mucosa
- Embryology:
- Week 3: lung and esophageal development
- Week 4: tracheo-esophageal fistula formation
- Tracheo-esophageal fistula: abnormal connection between the esophagus and trachea
- Polyhydramnios: excessive amniotic fluid
Stomach Pathologies
- Pyloric stenosis:
- Narrowing or stenosis of the pyloric sphincter
- Causes: hypertrophy of the pyloric sphincter
- Clinical manifestations: vomiting, epigastric pain, and fullness
- Gastroparesis:
- Delayed gastric emptying
- Causes: neuropathy, poorly controlled diabetes, and vagal dysfunction
- Symptoms: satiety, anorexia, vomiting, and retained gastric contents
- Gastritis:
- Inflammation of the stomach
- Causes: H. pylori, NSAIDs, and cigarette smoking
- Symptoms: epigastric pain, nausea, and vomiting
- Peptic ulcer disease:
- Loss of mucous balance
- Causes: H. pylori, NSAIDs, and cigarette smoking
- Symptoms: epigastric pain, nausea, and vomiting
Treatment and Management
- Decreasing HCL production:
- Turning down the PSNS
- Turning down histamine
- Turning down gastrin
- Managing bleeding ulcers:
- Cautery
- Clips
- Managing gastroparesis:
- Gastric drainage
- IV fluid and electrolytes
- Proton pump inhibitors or H2 blockers
- Surgery or stenting
Understand the normal physiology of the GI tract and the mechanisms of gastric acid secretion and mucosal protection. Learn about the neural control, processing of food, and secretory functions of the mouth, stomach, pancreas, liver, and intestines.
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