Flora - The GI Microbiota Flashcards
What are the 4 main types of bacterial phyla in healthy humans?
Firmicutes (majority)
Bacterioidetes
Actinobacteria
Proteobacteria
Other than nutrition, what are the other biological effects of the gut microbiota on the human host? (7)
- Development of innate and adaptive immunity
- Intestinal epithelial integrity
- Bile salt transformation
- Barrier to pathogens
- Breakdown of molecules
- Generation of gases
- metabolism of xenobiotics
What are the nutritional functions of gut microbiota?
- Synthesize vitamins K, B12 and other trace vitamins
- Digest carbs to short chain fatty acids
- Digest protein to ammonia
What is the theory of gut microbiotas link to obesity?
Obese people have more Firmicutes. These extract more energy from indigestible carbs -> extracting more calories
What is the sugar in human milk?
What is the bacteria found in human milk?
Lactose
Bifidobacterium
Bifidobacterium:
Gram + or -?
Effect on lactose?
PH?
Gram + bacteria
Ferments lactose -> acetic acid
PH 5 - 5.5
What ways are dairy and formula milk different to human milk?
Higher buffering capacity
Higher PH
Different flora
- Lactobacilli, bacteriocides etc
Why do normal flora colonies not infect the host? (2)
Barrier effect of intestinal mucosa
Immune recognition + no inflammation
Why might a disease be caused by normal gut flora? (5)
1) Damaged epithelial barrier
2) Organisms compromising natural defenses
3) Altered immune responses
4) Impaired phagocytic activity
5) Inflammation by pathogens
What provide a hostile environment for bacteria inside the inner mucosa?
Antibacterial toxins
Where does immune activity originate inside the mucous membranes?
Mucous-Associated lymphoid tissue
What is GALT? Where is it present?
Gut-Associated Lymphoid tissue
1) Single lymphoid follicles embedded in the intestinal wall
2) Aggregated follicles such as Peyer’s patches
What is NALT?
Nasopharynx-associated lymphoid tissue
What does antigenic (antibody stimulating) stimulation lead to?
1) Secretion of IgA into the lumen
2) These prevent antigens from adhering to mucous membranes
What are found in the Peyer’s patch?
Lymphoid follicle, perifollicular area, mesenteric lymph node, T cells, Neutrophils
