Unit 3 - GI Lecture 4 Flashcards
What are the consequences of atrophic enteritis?
- Markedly reduced surface area for digestion and absorption
- Villi are covered by immature cells with less digestive and absorptive capabilities
What does mechanism A of atrophic enteritis target?
superficial villus epithelial cells
What does mechanism B of atrophic enteritis target?
dividing crypt epithelial cells
What viruses use mechanism A of atrophic enteritis?
Rotavirus, Coronavirus (dogs, pigs), Coccidia (swine), Enteroinvasive bacteria (Salmonells, SEEC, E. Coli)
What agents use mechanism B of atrophic enteritis?
Parvovirus (cats, dogs), radiation, chemotheraputic agents
What agents use a combination of mechanisms A and B of atrophic enteritis?
Coccidia (bovine, Coronavirus (bovine), BVD (bovine)
What necropsy findings are associated with atrophic enteritis?
maldigestion, malabsorption, thin-walled intestine, watery diarrhea, mesenteric lymph nodes not typically enlarged
In the case of canine parvovirus, near complete loss of villus epithelial cells results in what?
an inability to digest and absorb, loss of mucosal integrity, and prolonged recovery
What is secretory diarrhea?
when pathogens produce toxins which result in increased active secretion
What is the pathogenesis of secretory diarrhea?
- Pathogenic strain attaches to villus epithelial cells by pili
- Pathogenic strain proliferates
- Release enterotoxins which increase intestinal secretion by altering electrolyte and water movement across the plasma membrane
- Secretory diarrhea
What necropsy/clinical findings are associated with secretory diarrhea?
watery diarrhea, rapid dehydration and death, mesenteric lymph nodes not typically enlarged, will have chyle in the lacteals
When does increased vascular permeability occur?
with inflammation of the intestinal mucosa
What is the pathogenesis of increased vascular permeability?
- Inflammation
- Release of inflammatory mediators
- vessel dilation
- Leakage of fluid and plasma proteins from vessels
In chronic cases if increased vascular permeability what can happen?
- Exudate continually seeps from the mucosal surface into the gut lumen
- Significant amount of plasma protein can be lost
- Panhypoproteinemia (protein losing enteropathy)
What is one function of the colon?
to reduce the volume of water and electrolytes lost in feces
What disorders in the colon causes diarrhea?
resorptive capacity surpassed due to increased fluid from the small intestine or resorptive functional capacity reduced
If there is a mild increase in fluid from the small intestine how does the colon respond and what is the clinical outcome?
the colon compensates by removing fluid from the colon and there is normal feces but decreased weight gain
If there is a marked increase in fluid volume from the small intestine how does the colon respond and what is the clinical outcome?
incomplete or colon compensation to remove fluid causing small bowel diarrhea
If thee is normal fluid volume in the small intestine and decreased fluid volume removed by the colon what is the clinical outcome?
large bowel diarrhea
If there is a marked increase in fluid volume from the small intestine and a decrease in fluid removal by the colon what is the clinical outcome?
explosive diarrhea
What is large bowel diarrhea due to?
the reduced capacity to absorb fluid and electrolytes presented from the small intestine
Describe the appearance of large bowel diarrhea.
frequent passage of small amounts of fluid feces occasionally with fresh mucus and undigested blood