Chapter 344 - Approach to the Patient with Gastrointestinal Disease Flashcards
How does the nervous system affect the gastrointestinal tract?
“Intrinsic gut wall nerves provide the basic controls for propulsion and fluid regulation. Extrinsic neural input provides volitional or involutary control to degrees that are specific for each gut region.”
Name the two main functions of the gastrointestinal (GI) tract.
“The GI tract serves two main functions - assimilating nutrientes and eliminating waste.”
What are the differences in functions of proximal versus distal stomach?
“The proximal stomach serves a storage function by relaxing to accomodate the meal. The distal stomach exhibits phasic contractions that propel solid food residue agasint the pylorus, where it is repeteadly propelled proximally for further mixing before it is emptied into the duodenum.”
What kind of nutrientes are absorved in the proximal intestine in comparisn to its distal portion?
“The proximal intestine is optimized for rapid abosrption of nutrient breakdown products and most minerals, whereas the ileum is better suited for absorption of vitamin B12 and bile acids.”
The ileocecal sphincter prevents coloileal reflux and maintains small-intestinal sterility,
True or False?
True.
Name the normal transit times in different gastrointestinal compartments.
“Whereas transit times in the esophagus are on the order of seconds and times in the stomach and small intestine range from minutes to a few hours, propagation through the colon takes more than 1 day in most inidividuals.”
Name the differences regarding function between the proximal and distal colon.
“The proximal colon serves to mix and absorb fluid, while the distal colon exhibits peristaltic contractions and mass actions that function to expel the stool.”
Name the main protective mechanisms of the gastrointestinal tract.
“Mucosal immune mechanisms include chronic lymphocyte and plasma cell populations in the epithelial layer and lamina propria backed up by lymph node chains to prevent noxious agents from entering the circulation. Antimicrobial peptides secreted by Paneth cells in the intestine further contribute to the defense mechanisms against pathogens in the lumen. All substances absorbed into the bloodstream are filtered through the liver via the portal venous circulation. In the liver, many drugs and toxins are detoxified by a variety of mechanisms.”
Which gastrointestinal functions might be altered by stress?
“The brain-gut axis further alters functions in regions not under volitional regulation. As an example, stress has potent effects on gut motor, secretory, and sensory functions.”
What is the most common intestinal maldigestion syndrome?
Lactase deficiency.
All the diseases that impair digestion and absorption might result in anemia, dehydration, electrolyte disorders, or malnutrion.
True or False?
False.
These outcomes might occur in celiac disease, bacterial overgrowth, infectious enteritis, Crohn’s ileitis, and radiation damage, for example. On the other end, enzyme deficiencies, such as lactase, do not produce adverse outcomes.”
How does Zollinger-Ellison syndrome might produce impaired digestion and absorption?
“Gastric hypersecretory conditions such as Zollinger-Ellison syndrome damage the intestinal mucosa, impair pancreatic enzyme activation, and accelerate transit due to excess gastric acid.”
Name conditions associated with acid gastric hypersecretion.
Zollinger-Ellison syndrome, G cell hyperplasia, retained antrum syndrome, and some patients with duodenal ulcers.
Name intestinal and colonic hypersecretion conditions associated with diarrhea.
“Common intestinal and colonic hypersecretory conditions cause diarrhea and include acute bacterial or viral infection, chronic Giardia or cryptosporidia infections, small-intestinal bacterial overgrowth, bile salt diarrhea, microscopic colitis, diabetic diarrhea, and abuse of certain laxatives. Less common causes include large colonic villus adenomas and endocrine neoplasias with tumor overproduction of secretagogue transmitters like vasoactive intestinal popypeptide.”
What is the most common cause of small-intestine and colonic obstruction?
Adhesions and cancer, respectively.
How do you define gastroparesis?
“Gastroparesis is the symptomatic delay in gastric emptying of meals due to impaired gastric motility.”
Name causes for constipation.
“Slow-transit constipation is produced by diffusely impaired colonic propulsion. Constipation also is produced by outlet abnormalities such as rectal prolapse, intussusception, or dyssynergia - a failure of anal or puborectalis relaxation upon attempted defecation.”
“Causes of constipation include obstruction, motor disorders of the colon, medications, and endocrine diseases such as hypothyroidism and hyperparathyroidism.”
Hyperthyroidism might cause accelerated transit with hyperdefecation.
True or False?
True.
Eosinophils in the esophageal histology are pathognomonic of eosinophilic esophagitis.
True or False?
False.
They might occur in other conditions such as gastroesophageal reflux disease.
Which microscopic colitides do you know and how do they differ from other inflammatory bowel diseases?
“The microscopic colitides, lymphocytic and collagenous colitis, exhibit colonic subepithelial infiltrates without visible mucosal damage.”
Which mechanisms might explain impaired gut blood flow?
“More commonly encoutered are intestinal and colonic ischemia that are consequences of arterial embolus, arterial thrombosis, venous thrombosis, or hypoperfusion from dehydration, sepsis, hemorrhage, or reduced cardiac output.”
Chronic ischemia may result in intestinal stricture.
True or False?
True.
What are tha main risk factors for esophageal cancer?
Chronic acid reflux for adenocarcinoma and alcohol or tobacco history for squamous cell cancer.
How does one explain familial clustering in functional bowel patients?
“Familial clustering is even observed in the functional bowel disorders, although this may be secondary learned familial illness behavior rather than a true hereditary factor.”
