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Flashcards in Week 237 - Chronic Diarrhoea Deck (35):
1

Week 237 - Chronic Diarrhoea: What is the time frame for diarrhoea to be classed as chronic?

>4 weeks

2

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

3

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.

4

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

5

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

6

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.

7

Week 237 - Chronic Diarrhoea: What is absorbed in the duodenum?

• Iron
• Ca, Mg, Zn

8

Week 237 - Chronic Diarrhoea: What role does the liver play in digestion?

Bile salts cause fats to form into micelles.

9

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)

10

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

11

Week 237 - Chronic Diarrhoea: What does the proximal ileum absorb?

• Fats and fat-soluble vitamins (ADEK)
• Water and water-soluble vitamins

12

Week 237 - Chronic Diarrhoea: What does the distal ileum absorb?

• Bile salts
• IF / vitamin B12 complex

13

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.

14

Week 237 - Chronic Diarrhoea: What does the colon absorb?

• Water
• Electrolytes
• Short chains FAs (Produced from microbial fermentation of dietary fibre)

15

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.

16

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+.

17

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.

18

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.

19

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.

20

Week 237 - Chronic Diarrhoea: Where is Guanylin secreted from? What is its function?

• Ileum, Colon
• Increases fluid absorption in the intestines.

21

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.

22

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.

23

Week 237 - Chronic Diarrhoea: Which transporter is responsible for glucose and galactose?

• SGLT1

24

Week 237 - Chronic Diarrhoea: Fructose is transported out of the gut by which transporter?

GLUT5

25

Week 237 - Chronic Diarrhoea: Starch and maltose breakdown into which monosaccharide?

Glucose

26

Week 237 - Chronic Diarrhoea: Lactose breaks down into which two monosaccharides?

Glucose and Galactose

27

Week 237 - Chronic Diarrhoea: Sucrose breaks down into which monosaccharides?

Glucose and Fructose

28

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)

29

Week 237 - Chronic Diarrhoea: How is lactose intolerance diagnosed?

• Lactose breath test.
- Increased H2 exhaled after laxtose ingestion.

30

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.

31

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.)

32

Week 237 - Chronic Diarrhoea: Deficiency of vitamin A can cause what?

• Compromised mucosa including xerophthalmia.
• Night blindness.
• Benign intracranial hypertension.

33

Week 237 - Chronic Diarrhoea: What are the complications of Vitamin D deficiency?

• Rickets/osteomalacia.

34

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.

35

Week 237 - Chronic Diarrhoea: What are the complications of vitamin K deficiency?

Coagulopathy - prolonged PT.