GI Tract

Question 1

What comprises the mucosal layer?

Answer 1

1. Epithelium
2. Lamina Propria
3. Muscularis mucosa

Question 2

What comprises the submucosal layer?

Answer 2

1. Meisnner’s Plexus (Submucosal plexus)

Question 3

What comprises the muscularis propria?

Answer 3

1. Circular smooth muscle
2. Auerbach’s Plexus (Myenteric plexus)
3. Longitudinal smooth muscle

Question 4

What comprises the outermost layer of the GI tract?

Answer 4

Serosa / Adventitia

Question 5

What does Meissner’s plexus mainly control?

Answer 5

GI secretions and local blood flow

Question 6

What does the Myenteric plexus mainly control?

Answer 6

Motility i.e. peristalsis of the GI tract
Secretion of Vasoactive Intestinal Polypeptide which cause relaxation of intestinal sphincters which allow passage of intestinal contents

Question 7

What are propulsive movements of the GI tract and what stimulates them?

Answer 7

Peristalsis

Stimuli: distention of the gut wall, strong parasympathetic stimulation and irritation of the epithelial lining of the gut

Question 8

Describe the process of peristalsis

Answer 8

1. Contractile ring appears on the oral side of the bolus
2. Contractile ring moves towards the distended segment of the gut
3. Pushes the contents towards the anus for 5-10cm

Question 9

What is receptive relaxation?

Answer 9

Relaxation of the gut for several cms downstream towards the anus

Allows easier passage of contents

Question 10

What is propulsive movements of the gut dependent on?

Answer 10

An active myenteric plexus