Lower GIT

Question 1

What is the function of the small intestine?

Answer 1

Mixing of digestive juices from the liver and pancreas, bicarbonate and chyme, facilitating neutralisation of acid within the chyme. Moving contents towards the colon slowly to allow time for the digestion and absorption and make way for the next meal

Question 2

What are the two mechanism of small intestine motility?

Answer 2

1. Spontaneous contractions of smooth muscle, increase in strength and frequency after a meal. Frequency is greater in the duodenum than the stomach (12 per min) and it is modulated by neural and humoural mechanisms.
2. Migrating motor complex, regular spontaneous contractions of the smooth muscle, that travel distally from the duodenum to the colon (duration of a segment is around 10 mins, during fasting they reduce to 1.5 times an hour)

Question 3

What is segmentation?

Answer 3

The mixing of contents, contraction of smooth muscle and relaxation of adjacent segments. Rhythmic division and subdivision of the contents. Contractions increase in frequency and strength in the content of chyme. Largest in the duodenum to allow the mining of bile and pancreatic juices with the acidic chyme.

Question 4

What is peristalsis?

Answer 4

Sequential contraction of adjacent areas of smooth muscle towards the colon, followed by relaxation from the proximal direction. Propels the chyme towards the colon. Each contraction travels approx. 10cm. Get occasional strong contractions that travel the entire length of the small intestine, known as peristaltic brushes.