Week 237 - Chronic Diarrhoea Flashcards
Week 237 - Chronic Diarrhoea: What is the time frame for diarrhoea to be classed as chronic?
> 4 weeks
Week 237 - Chronic Diarrhoea: How much fluid enters the GI system per day? Where does this come from? How much stool is created?
• 8-9L/day
- Ingest 1-2L
- Produce 7L (saliva, biliary, pancreatic)
• 100-200g/day of stool
Week 237 - Chronic Diarrhoea: What are the two main types of diarrhoea? Give a brief description of each.
- Osmotic diarrhoea - Caused by ingestion of poorly absorbed osmotically active substance that retains fluid within the lumen.
- Secretory diarrhoea - Disordered electrolyte transportation, net secretion of anions, causes a net inhibition of sodium absorption and therefore water.
Week 237 - Chronic Diarrhoea: What are the causes of secretory diarrhoea?
- Exogenous (Cholera toxin)
- Endogenous (e.g. neuroendocrine tumour)
- Absence of ion transporter
- Loss of intestinal surface area.
- Intestinal ischaemia
- Rapid intestinal transit
Week 237 - Chronic Diarrhoea: What exocrine cells can be found in the body/corpus of the stomach? What do they secrete?
- Chief Cells - Pepsinogen
* Parietal Cells - HCL, Intrinsic factor
Week 237 - Chronic Diarrhoea: What exocrine cells can be found in the antrum? What do they secrete?
- Chief cells - Pepsinogen
* Endocrine cells - G Cells - Gastrin, D cells - somatostatin.
Week 237 - Chronic Diarrhoea: What is absorbed in the duodenum?
- Iron
* Ca, Mg, Zn
Week 237 - Chronic Diarrhoea: What role does the liver play in digestion?
Bile salts cause fats to form into micelles.
Week 237 - Chronic Diarrhoea: What are the two exocrine functions of the pancreas?
- Duct cells - Produce bicarbonate and water to neutralise stomach acid.
- Acinar cells - Produce pancreatic juice for digestion of macronutrients (Proteases, Amylases, Lipases)
Week 237 - Chronic Diarrhoea: What does the jejunum absorb?
- Proteins
- Monosaccharides
- Some fat and fat soluble vitamins (ADEK)
- Water and water soluble vitamins
- Folate
- Ca, minerals, trace elements
Week 237 - Chronic Diarrhoea: What does the proximal ileum absorb?
- Fats and fat-soluble vitamins (ADEK)
* Water and water-soluble vitamins
Week 237 - Chronic Diarrhoea: What does the distal ileum absorb?
- Bile salts
* IF / vitamin B12 complex
Week 237 - Chronic Diarrhoea: What is the role of the ileo-caecal valve?
- Regulates/ delays flow of chyme from ileum.
* Prevents bacterial contamination of ileum.
Week 237 - Chronic Diarrhoea: What does the colon absorb?
- Water
- Electrolytes
- Short chains FAs (Produced from microbial fermentation of dietary fibre)
Week 237 - Chronic Diarrhoea: Where is cholecystokinin secreted from? What is its function?
- Duodenum, jejenum, ileum, colon.
* Increases pancreatic secretion and causes contraction of the gall bladder.
Week 237 - Chronic Diarrhoea: Where is gastrin secreted from? What is its function?
- G-cells in the gastric antrum.
* Stimulates parietal cells in the gastric body to secrete H+.
Week 237 - Chronic Diarrhoea: Where is gastrin releasing hormone secreted from? What is its function?
- Vagal nerves
* G cells in gastric antrum, increasing gastrin release.
Week 237 - Chronic Diarrhoea: Where is glucagon released from? What is its function?
- Produced by alpha cells in islets of Langerhans.
* Act on the liver to increase the production of glucose and breakdown of glycogen.
Week 237 - Chronic Diarrhoea: Where is somatostatin released from? What is its function?
- D cells in the stomach and duodenum, and delta cells of the islets of Langerhans.
- Causes multiple effects;
- Reduces production of gastrin in the stomach.
- Increases fluid absorption in the intestine.
- Reduces endo and exocrine secretions of the pancreas.
- Reduces bile flow.
Week 237 - Chronic Diarrhoea: Where is Guanylin secreted from? What is its function?
- Ileum, Colon
* Increases fluid absorption in the intestines.
Week 237 - Chronic Diarrhoea: What is the role of Vasoactive intestinal peptide? (VIP) Where is it secreted from?
- ENS neurones.
- Causes increased secretions of the small intestine and pancreas.
- Relaxes the smooth muscle of the small intestine.
Week 237 - Chronic Diarrhoea: What is the SGLT1 transporter responsible for? What is the co-transporter?
- Transport of Glucose and Galactose.
* Na is the co-transporter.
Week 237 - Chronic Diarrhoea: Which transporter is responsible for glucose and galactose?
• SGLT1
Week 237 - Chronic Diarrhoea: Fructose is transported out of the gut by which transporter?
GLUT5
Week 237 - Chronic Diarrhoea: Starch and maltose breakdown into which monosaccharide?
Glucose
Week 237 - Chronic Diarrhoea: Lactose breaks down into which two monosaccharides?
Glucose and Galactose
Week 237 - Chronic Diarrhoea: Sucrose breaks down into which monosaccharides?
Glucose and Fructose
Week 237 - Chronic Diarrhoea: What is the effect of unabsorbed lactose in the colon?
- Osmotic effect - Draws in water causing diarrhoea.
* Fermented by bacteria causing gas, and organic acids (acidic stools)
Week 237 - Chronic Diarrhoea: How is lactose intolerance diagnosed?
• Lactose breath test.
- Increased H2 exhaled after laxtose ingestion.
Week 237 - Chronic Diarrhoea: What are the causes of primary lactase deficiency?
Both genetic.
• Congenital - Extremely rare, osmotic diarrhoea from birth.
• Late-onset - After the age of 5 years, more common in asians and africans.
Week 237 - Chronic Diarrhoea: What is needed to absorb fats (and fat-soluble vitamins)?
- Bile salts to emulsify fats into micelles.
- Pancreatic lipase for digestion.
- Ileum for fat absorption.
- Terminal ileum for bile salt absorption (an intact ICV is needed for this.)
Week 237 - Chronic Diarrhoea: Deficiency of vitamin A can cause what?
- Compromised mucosa including xerophthalmia.
- Night blindness.
- Benign intracranial hypertension.
Week 237 - Chronic Diarrhoea: What are the complications of Vitamin D deficiency?
• Rickets/osteomalacia.
Week 237 - Chronic Diarrhoea: What are the complications of Vitamin E deficiency?
- Increased susceptibility to oxidative stress.
- Haemolysis.
- Neurological effects: peripheral neuropathy, ataxia, external ophthalmoplegia.
Week 237 - Chronic Diarrhoea: What are the complications of vitamin K deficiency?
Coagulopathy - prolonged PT.
