Gut microbiota Flashcards
What is normal flora?
Bacteria an individual is colonised with at birth which remain with the organism until death
When are normal flora normal?
When in the correct location
e.g. the gut not the bloodstream
What are transient microbiota?
Inhabit an individual for a brief period of time
Some cause disease, some don’t
Overall how many microorganisms are there in the body?
10^14
Why are certain bacteria only found in one location of the body?
Specifically adapted to life in one particular niche
Tissue preference
Colonisation site has specific receptors for attachment
Where is the most microflora in the body?
Intestines
How does the number of organisms vary across the GI tract?
It increases from stomach to colon
Highest number in the colon
Where are microflora found in the oral cavity?
Gingival crevice Gingiva Cheek Palate Tongue Tooth surface
What must microflora of the oral cavity be resistant to?
Mechanical removal
What is the bodies defence against microflora in the oral cavity?
Salivary glands secrete neutral pH solution to neutralise bacterial acids
Saliva contains lysozyme to attack bacterial peptidoglycan
What destroys microorganisms in the stomach?
Low pH
What keeps microflora under control in the intestines?
Motility
Mucin
What is the defence against microorganisms in the bowel?
Lymphoid aggregates
Secrete IgA plasma cells
What would happen if there was a decrease in saliva production?
Significant dental decay
What would reduced stomach acidity lead to?
Decreases the number of organisms required to initiate disease
What would happen if the oesophagus was perforated?
Polymicrobial mediastinitis
What happens to any bacteria that may enter the portal vein?
Cleared by macrophages
If the liver had cirrhosis, what would happen to any bacteria in the portal vein?
May enter the perihepatic lymphatic system
How can bacteria lead to diarrhoea?
Loss of or inhibition microvilli in the large intestine
Prevents water reabsorption
What would be the cause of blood and pus in the stools?
Organisms that invade the mucosa and destroy enterocytes
How is appendicitis caused?
Blockage of appendix lumen by faecolith
Flora trapped are still able to reproduce and cause complications
