Session 8 - Notes

Question 1

• What are intestinal crypts (intestinal glands)?

Answer 1

These are glands lining the intestinal epithelia which usually sit at the base of the villi. They secrete various enzymes and play a vital role in cell turnover in the gut. The base of these glands have cells that multiply and then migrate up to the tips of the villi where they are shed.

Question 2

• What is the ‘unstirred layer’?

Answer 2

This is a layer of water and mucus which lies adjacent to the intestinal wall. Enzymes secreted by the intestinal epithelia are trapped in this ‘unstirred layer’. Its function is to slow the diffusion of a variety of different sized molecules allowing them to be further broken down by the trapped enzymes therefore completing digestion.

Question 3

• What is meant by the term ‘segmentation’ and what are its main purposes?

Answer 3

Contraction of the intestinal smooth muscle whereby the intestinal contents are not simply propelled in one direction but undergo a gentle agitation and mixing by a back and forth movement. The contraction of the muscle produces small ‘segments’ along the length of the involved gut, hence the term segmentation.

Question 4

• How does segmentation differ from peristalsis?

Answer 4

Peristalsis is the coordinated contraction of the smooth muscle of the gut with the aim of propelling luminal contents in one direction. Movement is the primary purpose.
Segmentation as described above has its purpose more in the agitation and mixing of luminal contents. Due to the intestinal pacemakers firing more rapidly at their proximal locations, segmentation does create a slow caudal progression of intestinal contents.

Question 5

• What is the Gastro-colic reflex?

Answer 5

This is a reflex whereby the stretching of the stomach following a meal initiates peristalsis within the gut. This can include mass movements and hence the urge to defecate can be stimulated by eating.

Question 6

• What treatment options are available for Pernicious anaemia?

Answer 6

These patients need to be given adequate doses of Cobalamine for the rest of their lives. This is usually given as an injection, but once normal body levels have been established and stabilised, an oral dosing regime is possible.

Question 7

What is Coeliac Disease

Answer 7

Autoimmune disease which causes malabsorption, a partial/total absence of vili of the duodenum. Related to gluten allergy/