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Diarrheal Disease

Terms in this set (16)

What kind of cells line the intestine?
simple columnar epithelium
What is the intestinal mucosa?
The uppermost layer of the intestine, in contact with the lumen. These simple columnar epithelial cells absorb nutrients from foods and then pass them into the submucosa, where they enter blood vessels or lymphatic vessels.
What is the lumen of the intestine?
open space where the food passes through our bodies. Lumen is latin for "opening"
What are normal flora?
the normal microbes that are found in great variety in and on a healthy body. They help to prevent pathogenic organisms from taking hold and to prevent opportunistic pathogens from growing in amounts or places that they shouldn't.
What does it mean to be a "carrier" of a microbial disease?
The organism carries the bacteria or microbe but is not sickened by it. The most famous example is Typhoid Mary. In the case of diarrheal diseases, some animals (cows, pigs, deer) can carry E.coli O157:H7 without being sick, but they can pass to humans by contaminated food products (often lettuce and other salads)
Shigella
Gram-negative rod that can cause dysentery.
E.coli O157:H7
most virulent strain of E.Coli - famous for causing enterohemorrhagic dysentery. Unlike normal E.coli, it produces Shiga toxin which can cause bloody diarrhea.
Shiga toxin
*binds to host receptor to enter
*inhibits protein synthesis in cells
*can destroy endothelial cells, causing hemorrhage
*can damage kidney capillaries, leading to hemolytic uremic syndrome
Why is antibiotic therapy risky for treatment of bacterial dysentery?
Although it may still be useful, it should be undertaken with caution because endotoxin can be released from the Gram negative pathogen, which can lead to a cytokine storm and septic shock.
Hemolytic Uremic Syndrome (HUS)
Serious condition characterized by red blood cell breakdown and kidney failure
Listeria monocytogenes
Gram positive rod bacteria that can cause food-borne illness (usually associated with vegetables and fruits). It spreads intracellularly, by first triggering endocytosis into intestinal cells, and then harnessing host actin to move from cell to cell.
How does our adaptive immune system fight off diarrheal diseases?
Antigen-presenting cells activate helper T cells. These cells then stimulate cytotoxic B cells to directly destroy the pathogen (cell-mediated immunity) and B cells to produce antibodies that neutralize the bacteria or its toxins.
What is reactive arthritis?
Arthritis that results from antibodies produced to infections, particularly after GI infections.
How is Rheumatic Fever similar to Reactive Arthritis?
Both are caused by cross-reactivity of antibodies made to a pathogen that then damage host tissues.
Vibrio cholera
This curved-shaped gram negative rod causes classic "rice water" diarrhea, in which copious amounts of water are lost from the intestine.
cholera toxin
causes electrolytes to leave intestinal cells and water follows, leading to dehydration and electrolyte imbalance.
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