Gut microbiota and Immunity Flashcards
Identify the main levels of gut defense, giving examples.
1) Physical (e.g. skin, mucosa, secretions)
2) Innate immunity
3) Acquired immunity (antibodies)
Identify the main host defenses in the mouth.
- Flow of liquids (flushes bacteria)
- Saliva (contains antimicrobials + growth factors which aid wound healing and therefore help protect mucosa)
- Antimicrobials (lysozymes, lactoferrin, IgA, sIgA, peroxidase)
- Microbiota
Identify the main host defenses in the esophagus.
- Flow of liquids
- Peristalsis (pushes bacteria out)
Identify the main host defenses in the stomach.
- Acid pH (1 or 2, produced by parietal cells)
- Antimicrobials (beta defensins)
- Mucus (protects us against acid + prevents bacteria from easy attachment)
Identify the only bacteria that lives in the stomach.
Helicobacter Pylori
Define hypochloridia and achloridia. How are these significant wrt gut immunity ?
Less production of acid
No production of acid
They predispose to infection
Identify the main host defenses in the small intestine.
- Flow of gut contents
- Peristalsis
- Mucus
- Bile (acidic)
- Secretory IgA (main agent of mucosa immunity, only immunoglobulin that passes through mucosa membranes)
- Antimicrobial peptides (lysozymes, alpha defensins, beta defensins)
- Microbiota
Are alpha defensins found in the stomach ?
No, only small intestine
Identify the main host defenses in the large intestine.
- Peristalsis
- Mucus
- Microbiota
- Shedding and replication of epithelium (if damaged or infected, we want to get rid of it)
Identify the different possible types of host-bacteria relationships.
- Commensal (bacterium benefits, host neither harmed nor benefits)
- Symbiotic (both benefit)
- Parasitic (bacterium benefits, other is harmed)
Can bacteria in commensal/symbiotic relationships become parasitic ?
Yes, under the right conditions
Define probiotics.
“Live bacteria and yeasts that also called “the good” microorganisms because they benefit the the digestive system.”
Identify examples of probiotics.
Lactobacillus spp.
Bifidobacterium spp.
Bacteroids spp.
Identify ways in which probiotics ‘benefit’ the digestive system.
- Produce lactic acid (acidic conditions unfavorable to most bacteria)
- Produce bacteriocins (antimicrobial peptides)
These allow them to adhere to colonise areas instead of potentially harmful bacteria.
Define prebiotics.
Non-digestible food ingredients (especially carbs) which stimulate growth and activity of gut microbiota (not digested by stomach acid, so gets through to intestines).