Lower GI Structure/Function

Question 1

What is the main difference between segmentation and peristalsis?

Answer 1

Segmentation happens when material is being digested
Peristalsis moves material forward, after the nutrients have been absorbed
(note: these are two types of bowel contractions and are mutually exclusive)

Question 2

What does MMC stand for?

Answer 2

Migrating Motility Complex

Question 3

Describe the importance of intestinal bacteria in the digestive process

Answer 3

Bacterial fermentation of undigested carbohydrate

• releases short-chain fatty acids which are absorbed and used as an energy source
• also synthesise vitamin K which is important for blood clotting

Question 4

What type of epithelium is present in the rectum?

Answer 4

simple columnar epithelium

Question 5

Which anal sphincter is under involuntary control? (ie is controlled by smooth muscle)

Answer 5

Internal anal sphincter

Question 6

Which anal sphincter is under voluntary control? (ie is controlled by skeletal muscle)

Answer 6

Outer anal sphincter

Question 7

What type of epithelium is present in the anus?

Answer 7

stratified squamous epithelium

Question 8

Which nerves are involved in defecation?

Answer 8

Pelvic splanchnic nerves

Question 9

What triggers the defecation reflex?

Answer 9

Rectum wall distends due to faecal material and activates mechanoreceptors

Question 10

What causes symptoms in patients with constipation?

Answer 10

Distension of rectum (not absorption of toxins from faecal material)