Lecture 33 - Digestive System Disorders

Question 1

Why is the native flora of the mouth different from that of the small intestine and colon?

Answer 1

Native flora in small intestine and colon are coated in mucin. Stimulates IL-10 and inhibits IL-2

Question 2

What steps lead to dental caries?

Answer 2

I. Streptococcus mutans forms a biofilm in presence of sucrose.
II. Acid fermentation lowers the oral pH
III. enamel dissolves below 5.5

Question 3

Where does Helicobacter pylori live? How does it make you sick?

Answer 3

It is native to the stomach flora
It thins the mucus lining so the stomach acid will erode the epithelial tissue. Leads to formation of ulcers

Question 4

Name two virulence factors associated with H. pylori

Answer 4

produces urease and VacA toxin

Question 5

How does cholera toxin produce symptoms of cholera?

Answer 5

B part bind epithelial cell receptors
A part ADP-ribosylates a regulatory protein which leads to excess cAMP secretion into gut.
Symptom is diarrhea, or rice-water stool.

Question 6

How is cholera transmitted?

Answer 6

ingestion of seafood/copepods or drinks from fecal-contaminated water

Question 7

How can you avoid cholera?

Answer 7

“boil it, peel it, cook it, or forget it”
only drink bottled water

Question 8

How can you treat cholera?

Answer 8

administer “oral rehydration salts”

Question 9

What are the symptoms of dysentery (enteritis)?

Answer 9

cramps and diarrhea with blood

Question 10

What causes dysentary?

Answer 10

1. Shigella
2. E. coli
3. Campylobacter
4. Salmonella

Question 11

Differentiate between Salmonella and Shigella infection mechanisms

Answer 11

Both taken up via M cells
Shigella produces shiga toxin and uses actin tails to travel
Salmonella enters macrophages

Question 12

Name an autoimmune sequela associated with enteritis caused by Campylobacter

Answer 12

Guillain Barre Syndrome which is demyelination of the nerves

Question 13

Differentiate between typhoid fever and Salmonella enteritis

Answer 13

Salmonella enters macrophages and causes diarrhea
Typhoid fever is when it disseminates in the blood and colonizes the gallbladder

Question 14

What are the symptoms of mumps and why they are worse in adults than in kids

Answer 14

causes tissue swelling which is especially bad in testicle and ovary organs

Question 15

How have sound epidemiological practices prevented an outbreak in the Midwest?

Answer 15

Identified and quarantined (5 days) the first case and their network.
Also gave MMR vaccinations

Question 16

Differentiate between rotavirus and norovirus with respect to symptoms and at-risk population?

Answer 16

rotavirus: infects children and causes diarrhea
Norovirus: infects adults (that eat shellfish) and causes diarrhea, nausea, vomiting

Question 17

Transmission of Hepatitis viruses

Answer 17

A and E are foodborne (fecal-oral)
B, C, D are spread by sex, needles, sharing razors, or toothbrushes

Question 18

Symptoms of Viral Hepatitis

Answer 18

I. Jaundice
II. Abdominal Pain
III. Fatigue
IV. Nausea
V. Diarrhea

Question 19

What is the unique replication mechanism of Hep B virus

Answer 19

It uses an RNA intermediate & own reverse transcriptase to make new DNA

Question 20

How do you prevent the various types of hepatitis?

Answer 20

A: inactivated vaccine
B: recombinant vaccine
C-E: no vaccine

Question 21

What are the symptoms of Giardia?

Answer 21

“explosive’ foul-smelling diarrhea and gas
greasy stool

Question 22

How do you avoid and treat Giardia?

Answer 22

filter all drinking water on hiking trips or boil it
treat with metronidazole

Question 23

What are the symptoms of Cryptosporidium?

Answer 23

cramps and water diarrhea

Question 24

What is the biggest Crypto outbreak in history?

Answer 24

Milwaukee water facility incident

Question 25

How does the life-cycle of Entamoeba histolytica cause the symptoms of amoebic dysentery?