Neural & Hormonal Control of Gastrointestinal Function 2

Question 1

What causes relaxation of the pylorus?

Answer 1

activity of enteric neurons

Question 2

What is the protease present in the stomach?

Answer 2

pepsin

Question 3

Why is the food ground up in the stomach?

Answer 3

So it is available to digestive enzymes in the duodenum

Question 4

Why is there slow release of stomach contents into the duodenum?

Answer 4

Because the duodenum can only deal with the acid in small amounts

Question 5

What is the last nutrient to reach the duodenum?

Answer 5

Fat

Question 6

What are the three things that activate neural feedback?

Answer 6

acid, distension and nutrients (mostly amino acids)

Question 7

What thing in the duodenum inhibits gastric emptying?

Answer 7

acid - via the vasovagal reflex

Question 8

What does acid in the duodenum activate?

Answer 8

D cells to release somatostatin

Question 9

What is the action of somatostatin released in the duodenum?

Answer 9

excites terminals of vagal afferents to trigger vasovagal reflex that causes Brunner’s glands to release mucus and bicarbonate

Question 10

What do amino acids and fatty acids activate in the duodenum?

Answer 10

CCK release from I cells

Question 11

What is the action of CCK?

Answer 11

excites vagal neurons to regulate appeptite and enteric neurons to set up motor activity in the intestine

Question 12

What else do amino acids activate in the duodenum?

Answer 12

The release of secretin from S cells

Question 13

What is the action of secretin?

Answer 13

Causes secretion of bicarbonate from the pancreas

Question 14

What is the action of bicarbonate?

Answer 14

neutralises gastric acid to inactivate pepsin and to stop somatostatin secretion and also to re allow gastric emptying - also allows enzymes in the duodenum to work

Question 15

How does the pancreatic secretions access the duodenum above the pancreatic duct?

Answer 15

Via retropulsion

Question 16

What is the action of CCK as a hormone?

Answer 16

release of digestive enzymes from the pancreas, acts on hypothalamus to partly suppress appetite, gall bladder contraction

Question 17

How does the mucosa get sensory information?

Answer 17

Via mechanical stimulation activating mechanoreceptors and nutrients stimulating EE and EC cells

Question 18

What is the action of taste receptors in the lumen of the GIT?

Answer 18

cause release of serotonin from EC cells

Question 19

What are L cells?

Answer 19

cells which express the components of sweet taste receptors and release glucagon like peptide 1 and 2 and pancreatic polypeptide Y to regulate appetite and insulin secretion

Question 20

What is the action of olfactory receptors on EC cells?

Answer 20

release of serotonin from the EC cells

Question 21

What are the motor patterns activated in the duodenum?

Answer 21

segmentation, peristaslsis and retropulsion

Question 22

What modulates proportion of segmentation and peristalsis?

Answer 22

nutrients activating EE and EC cells

Question 23

What determines efficacy of digestion and absorption?

Answer 23

rate of transit

Question 24

What are the short chain fatty acids produced by fermentation?

Answer 24

acetate, butyrate, propionate

Question 25

What triggers urge to defacate?

Answer 25

distension of rectum

Question 26

What happens in irritable bowel syndrome?

Answer 26

the threshold is reduced and can sense content that is not normally detectable

Question 27

How is the anal sphincter relaxed?

Answer 27

with conscious neural activity

Question 28

What is the migrating motor complex?

Answer 28

A wave of contraction in the fasting state to clear bacteria and cellular debris

Question 29

What is ghrelin?

Answer 29

a growth hormone release inhibitor - released from the stomach in the fasted state - stimulates appetite

Question 30

What is gastrin releasing peptide?

Answer 30

a hormone in nerve terminals near G cells that acts in parallel with vagally release acetylcholine