1. What is the main function of the small intestine?

This is the principle site for the absorption of carbohydrate, lipid, proteins, water, electrolytes, vitamins and essential minerals.

2. What is the transit time for chyme to pass through the small bowel?

2–4 h.

3. What are the three main types of small bowel motion seen after a meal?

• Peristalsis: in common with the rest of the gut

• Segmentation: more frequent than the above, occurring about 8 times per minute in the ileum, lasting for several seconds. Involves localised contraction of 1–2 cm of bowel that leads to the propulsion of chyme in both directions. Important for mixing chyme with the digestive juices

• Pendular movements: longitudinal muscle contractions lead to movement of the bowel wall over luminal contents. Also important for mixing

4. How does the motility differ when the small bowel is empty of contents?

During fasting, a migrating motor complex spreads from the duodenum to the ileocaecal junction. This contractile wave helps to clear the small bowel of any remaining contents.

5. What is the composition of small bowel secretions?

This is made up of mucous, water and NaCl, predominantly.

6. What is the output of this daily?

1, 500 mL per day.

7. How does this compare to the rest of the gut?

The daily volume of gut secretions in (mL per day) may be summarised:

• Saliva: 1,500

• Gastric: 2,000

• Bile: 500

• Pancreatic: 1,500

• Small intestine: 1,500

8. How much water does the small bowel absorb per day?