Summary
Summary An Approach to Diarrhoea and Vomiting
- Course
- Medicine
- Institution
- University Of Cape Town (UCT)
These provide a comprehensive approach to the pathophysiology, aetiology and approach to diarrhoea and vomiting.
[Show more]
Seller
Follow
Content preview
Diarrhea and VomittingThe GIT produces large volumes of isotonic fluid to assist digestion and absorption of food
(±8 litres/day in an adult)
Note: isotonic fluid having the same tonicity or osmotic pressure as blood.
This fluid (and accompanying electrolytes) is ‘borrowed’ from the ECF and is later returned.
This ‘borrowed’ fluid (along with electrolytes) is not returned in 2 situations:
1.) Vomiting
2.) Diarrhea
The result/consequence of these thieves of the body is the following:
- Loss of water
- Loss of important ions, including: Na+, K+, Cl-, HCO3
Which ions are lost depends on?
This depends on the nature of the clinical presentation:
- diarrhoea loses HCO3-, Na+ and K+ → acidosis
- vomiting loses H+, Cl- and K+ → alkalosis
, The different types of diarrhea:
There are 4 main pathophysiological mechanisms of diarrhea:
1.) Osmotic Diarrhea
2.) Secretory Diarrhea
3.) Dysmotility Diarrhea
4.) Exudative Diarrhea
1.) Osmotic Diarrhea:
- Ingestion of poorly absorbed sugars or alcohols (e.g. mannitol, sorbitol) or ions (as found in
laxatives - magnesium, sulphate, and phosphate) leads to osmotic diarrhea
- Since the intestines cannot maintain an osmotic gradient, these unabsorbed ions in the
intestinal lumen cause retention of water to maintain an intraluminal osmolality equal to
that of body fluids (about 290 mOsm/kg) (i.e. water does not get absorbed but
instead remains or gets retained in the lumen)
- The diarrhea disappears with fasting or cessation of ingestion of the
offending substance
Examples
o Lactose intolerance, results due to deficiency of disaccharidase lactase
Lactulose, a synthetic disaccharide cannot be hydrolyzed by the human
intestine and cannot be absorbed intact in greater than trace amounts (thus
causing increased intraluminal osmolality).
After prolonged periods of bowel rest, mucosal atrophy develops resulting
in malabsorption and diarrhea
o Fat malabsorption
Hydrolysed to fatty acids (ions) by colonic bacteria
2.) Secretory Diarrhea:
- Net secretion of Cl- or HCO3- or inhibition of net Na+ absorption is the mechanism for this
diarrhea
Causes:
- The most common cause for secretory diarrhoea is infection
- Infectious agents (bacteria, parasites and viruses) produce enterotoxins
that interact with receptors and lead to increased anion secretion (e.g.
this is the case of cholera toxin – see biochem notes).
Or these enterotoxins may block specific absorptive pathways (e.g. Na-H exchange)
- Peptides produced by endocrine tumours such as vasoactive
intestinal peptide or calcitonin cause secretory diarrhea by
stimulating secretion by epithelial cells
- Significant loss of surface area of intestines (e.g. after resective
surgery, inflammatory bowel disease), may compromise water
absorption and cause diarrhea
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller maximusmeridius. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R133,00. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73918 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy summaries for 14 years now