Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GI- Week 1 > Pathology of Diarrhea > Flashcards

Pathology of Diarrhea Flashcards

1
Q

What is diarrhea?

A

Clinically: an increase in the frequency, volume, or urgency of defecation with or w/out change in consistency (normal stool frequency is defined from 3BM/week up to 3 BM/day)

Physiologically: 200+ gm stool/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

So most of what our gut deals with is what we produce, not food!

A

notice how most is absorbed by the small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What drives fluid uptake from the GI tube?

A

It follows Na+ absorption via Na/glucose co-transporters and NHEs in the small intestine villi and ENaC (epithelial channels) in the large intestine crypts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two main categories of causes of diarrhea?

A

1) increased intraluminal fluid (from decreased absorption or increased secretion)
2) Rapid GI transit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main cause of decreased absorption leading to diarrhea?

A

it is an osmotically driven event caused by ingestion of unabsorbable solutes that lead to a subsequent lack of absorption of fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the main cause of increased secretion leading to diarrhea?

A

this is a secretory mechanism that causes fluid to follow and leads to an electrolyte heavy stool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Most inflammatory diarrheas involve pathology of the ______

A

colon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some causes of Osmotic Diarrhea?

A

•Non-absorbable carbohydrates

–lactose (milk, yogurt, cheese, etc.)

–sorbitol, mannitol (diet soda, gum, candy)

–lactulose (Rx for hepatic encephalopathy)

•Non-absorbable electrolytes (laxatives)

–Mg2+ compounds (MOM, Maalox, Epsom salts)

–Golytely (PEG) prep for colonoscopy

–Fleets phosphosoda prep

•Miscellaneous malabsorption syndromes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The key to all secretory diarrheas is excessive ___ secretion into the gut

A

Cl- (secreted throuh apical CFTR channels)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does vibrio cholerae cause a secretory diarrhea?

A

It produces a toxin that activates the basolateral adenylate cyclase to increase cAMP which causes:

1) hyperactivity of the apical CFTR channel
2) inhibition of apical Na/H+ exchangers and Cl/HCO3 exchangers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is cholera induced diarrhea tx?

A

The WHO’s oral rehydration formula for the treatment of cholera and other secretory diarrheas is based on exploitation of the Na/glucose co-transporter. By including glucose in a high salt drink, Na+ absorption can continue despite cAMP inhibition of Na+ absorption by NHE.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are some other causes of secretory diarrhea that work through increased cAMP?

A

Heat labile and stable E. Coli enterotoxins

VIP (neurohumoral agent)

histamine and prostaglandins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some other causes of secretory diarrhea that work through increased Ca2+?

A

Yersinia toxin

Ach and Serotonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are some other causes of secretory diarrhea?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What tumors are associated with secretory diarrhea?

A

VIPoma

carcinoid

medullary carcinoma of the thyroid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are some pathologies that cause direct cell death leading to diarrhea?

A

Ameba, Shigella, Rotavirus

Giardia, Cryptosporidium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are some pathologies that cause cell death via immune-mediated mechanisms (complement, cytokines, cytotoxic T-cells, mastcells, neutrophils, etc) leading to diarrhea?

A

Crohn’s disease, ulcerative colitis, Whipple’s disease, Salmonella, Campylobacter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is acute diarrhea?

A

this is defined as diarrhea lasting less than 3 weeks that is almost exclusively caused by infection, causing a self-limited secretory or inflammatory diarrhea that can be treated with supportive (fluids) measures alone typically

22
Q

T or F. Cholera causes damage to the intestinal mucosa

A

F. It will not kill us any other way then by promoting dehydration

23
Q

Viruses no matter where you are, are the most common cause!

A
24
Q

described as Falling leaves. Giardia is seasonal!

Typically presents as a dyspepsia

A
25
Q
A
26
Q
A
27
Q

Most likely secretory diarrhea

A
28
Q

How would acute, non-bloody, no dehydrating diarrhea be treated?

A

–likely viral or toxin mediated, self-limited

–p.o. fluids, +/- Peptobismol

29
Q

How would acute, bloody (dysentery), non-dehydrating diarrhea be treated?

A

–likely bacterial (salmonella, shigella, campylobacter), often self limited

–obtain stool for culture, O&P

–p.o. fluids, Peptobismol

30
Q

How would acute dehydrating (with or without blood) diarrhea be treated?

A

-likely cholera

–obtain stool for culture, O&P

–IV fluids vs. oral WHO rehydration solution

–anti-diarrheal agent

31
Q

How would acute dehydrating, bloody, ‘septic’ diarrhea be treated?

A

–obtain stool for culture and O&P

–hospitalization, IV fluids

–IV fluoroquinolone (cipro); avoid with EHEC

32
Q

What are some risk factors for iatrogenic C. diff colitis?

A

–Antibiotic usage

–Extremes of age

–Hospitalization or institutionalization

33
Q

What causes C. diff colitis?

A

C. diff is commensal so ABX allow it to flourish and produce cytoxins A and B which destroy intestinal mucosa and promote formation of pseudomembranes

34
Q

How is C. diff colitis diagnosed?

A

–pseudomembraneous colitis on rectal endoscopy (below)

–Stool assay for Toxin A (+/- B)

35
Q

How is C. diff colitis treated?

A

–stop the offending antibiotic (if possible)

–metronidazole or vancomycin po

–cholestyramine to bind toxins

36
Q

C. diff is highly infectious!

A
37
Q
A
38
Q

What are some causes of chronic diarrhea with NO mucosal injury?

A

•Maldigestion and Malabsorption Syndromes

–Disaccharidase deficiencies, Bacterial overgrowth, Pancreatic insufficiency, Short bowel syndrome (after surgery/congenital)

•Hypermotility

–Irritable Bowel Syndrome, Hyperthyroidism, Diabetic neuropathy, Alcoholism

•Neuroendocrine Malignancies

–VIPoma, carcinoid

•Factitious

–Laxative abuse

39
Q

How does lactase deficiency present?

A

An osmotic diarrhea, with flatulence and acidic stool pH

40
Q

bacteria should not be in the small bowel!

A

Unconjugate bile acids cause a secretory diarrhea when they reach the colon. Take ABX to clean out the small bowel

41
Q

Basically the diagnosis would be if you had abdominal pain (have to have pain/bloating for diagnosis)/bloating with either the constipation or diarrhea and relief of those symptoms when bowel function returns to normal

There isnt anything functional with the bowels in IBS

A
42
Q

How is IBS treated?

A

–anti-cholinergic medications (diarrhea)

–5-HT receptor antagonists (constipation)

–reassurance

43
Q

What are some causes of chronic diarrhea WITH mucosal injury?

A

•Chronic Infections

–HIV, Parasites / worms (Strongyloides, etc.), Tropical sprue and Whipple’s disease

•Allergic / Immune-mediated

–Food allergy (milk, soy, etc.), Celiac sprue,Inflammatory Bowel Disease (Crohn’s and Ulcerative Colitis), Eosinophilic gastroenteritis

–Microscopic (lymphocytic and collagenous) colitis

•Malignancies

–Colon cancer

–Lymphoma

44
Q
A
45
Q

UC is only in the colon with CD can be in the colon or the small bowel or both

A
46
Q

What is microscopic colitis?

A

•Two Types (Lymphocytic and Collagenous colitis) marked by a chronic watery, non-bloody diarrhea in adults

47
Q

How is microscopic colitis tx?

A

–Bismuth

–Aminosalisylates

–steroids

48
Q
A
49
Q

Notice the nocturnal diarrhea!

A
50
Q
A

GI- Week 1 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions