GI: Dealing with toxins Flashcards Preview

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Flashcards in GI: Dealing with toxins Deck (12):
1

What are the innate physical defences we have against toxins?

Sight, smell, memory, saliva (slightly acidic), gastric acid, small intestine secretions, colonic mucus, anaerobic environment in the small bowel and colon, peristalsis and segmentation to move contents along

2

What microorganisms are resistant to gastric acid?

- mycobacterium tuberculosis is acid and alcohol fast
- h pylori produces urease which forms a protective cloud of ammonia
- enteroviruses eg hep A B, polio and coxsackie

3

What is the main role of the colon?

Water recovery

4

What are the innate cellular defences we have against toxins?

Neutrophils, macrophages, natural killer cells, tissue mast cells, eosinophils

5

What are the 3 causes of eosinophilia? (high eosinophil count)

1. asthma
2. hay fever
3. parasitic infections - eosinophils contain granules with perforins and peroxidases which can puncture holes in worms

6

Where are most of the macrophages located in the body?

80% in liver (specialised, called kupffer cells and sit in gaps in the endothelium), lots in spleen and lungs

7

What are the causes of liver failure?

Viral hepatitis is the most common globally
Alcohol
Drugs such as paracetamol
Industrial solvents
Mushroom poisoning

8

Why can liver failure lead to hepatic encephalopathy?

Ammonia is produced by colonic bacteria and deamination of AA - usually processed to urea in the liver however this is reduced.
Levels of ammonia increase - can cross the BBB and very toxic to the brain

9

What causes portosystemic shunting? and how does this present?

When there is hepatic fibrosis this leads to portal venous hypertension leading to portosystemic shunting (and therefore toxin shunting).
Presents as oesophageal varices, haemorrhoids and caput medusae (varices of gut, butt and caput)

10

What are the adaptive defences we have against toxins?

B lymphocytes - produce antibodies such as IgA and IgE that are effective against extracellular microbes
T lymphocytes - directed against T lymphocytes

11

What is GALT and what 3 locations is it nodular?

GALT is Gut Associated Lymphoid Tissue
It is nodular in 3 location - tonsils, peyers patches (submucosal lymphatics in terminal ileum), appendix

12

What is the potential complication of nodular GALT in the appendix?

Lymphoid hyperplasia in the appendix base leads to obstructive outflow, therefore there is stasis and infection - leading to appendicitis.
(another cause of obstructed appendix is faecolith or a worm blocking the exit)

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