6.1. Regulation in the gastrointestinal tract: enteric nervous system and gastrointestinal hormones.

Question 1

I. Main functions of the gastrointestinal system
1. What are the Main functions of the gastrointestinal system?

Answer 1

Question 2

I. Main functions of the gastrointestinal system
2. One of the main functions of GI system is
“Involvement in water and electrolyte balance”
=> Give an example to explain this function further

Answer 2

Example: cholera
=> cardiovascular shock, because e.g. 15L loss of water (+ electrolytes)
=> decrease in perfusion of vital organs (deadly!)

Question 3

I. Main functions of the gastrointestinal system
3. One of the main functions of GI system is
“Immune functions”
=> Give an example to explain this function further

Answer 3

• 80% of immune cells are found in the GI-wall, because many (harmful) bacteria and viruses are present in the GI-tract

Question 4

II. Regulation of the GI-system
1. What are the 3 major control mechanisms in the GI-system?

Answer 4

(1) neural
(2) endocrine
(3) paracrine

Question 5

II. Regulation of the GI-system
2A. What are the features of neural regulation of GI-system?

Answer 5

• The GI-tract is regulated by the autonomic nervous system, which has an extrinsic component (SYM + PARA innervation = CNS) and an intrinsic component (enteric nervous system – ENS)
• ENS is contained in the submucosal and myenteric plexuses.
• The ENS and CNS work together to regulate the

Question 6

II. Regulation of the GI-system
2B. Where can you find enteric nervous system (ENS)?

Answer 6

In the submucosal and myenteric plexuses.

Question 7

II. Regulation of the GI-system
2C. What are the 3 types of neural regulation involved?

Answer 7

1. Parasympathetic (PARA)
2. Sympathetic (SYM): INHIBITORY EFFECT!
3. Enteric nervous system (ENS)

Question 8

II. Regulation of the GI-system - .Neural regulation
2D. How does Parasympathetic (PARA) neural regulation occur?

Answer 8

Question 9

II. Regulation of the GI-system - Neural regulation
2E. How does Sympathetic (SYM) neural regulation occur?

Answer 9

Question 10

II. Regulation of the GI-system - Neural regulation
2F. How does neural regulation occur in Enteric nervous system (ENS)?

Answer 10

Question 11

II. Regulation of the GI-system - Neural regulation - Enteric nervous system (ENS)
2G. What is the role of opioids?

Answer 11

opioids have an inhibitory effect = stop the motility
=> no bowel movement (constipation)

Question 12

II. Regulation of the GI-system - Neural regulation - Enteric nervous system (ENS)
2H1. Classification of NT in ENS

Answer 12

Question 13

II. Regulation of the GI-system - Neural regulation - Enteric nervous system (ENS)
2H2. What are non-peptides NT in ENS?

Answer 13

• ACh
• Serotonin
• ATP
• NO
• Glutamate

Question 14

II. Regulation of the GI-system - Neural regulation - Enteric nervous system (ENS)
2H3. What are peptides NT in ENS?

Answer 14

• Substance P (SP)
• Opioids
• GRP
• VIP
• Stomatostatin

Question 15

II. Regulation of the GI-system - Neural regulation - Enteric nervous system (ENS)
2I. Make a schematic diagram of GI reflexes?

Answer 15

Question 16

II. Regulation of the GI-system - Endocrine regulation
3A. What happen in endocrine regulation?

Answer 16

• Enteroendocrine cell (EEC) is the sensor cell in the GI- tract. EEC responds to a stimulus by secreting a regulatory peptide/hormone that reaches its target cells by travelling in the bloodstream.
• Many GI hormones (mostly peptides) act as neurotransmitters in the ENS and in the brain.
• The synthesis and secretion are caused by specific stimuli, and regulates the functions of self/other cells.

Question 17

II. Regulation of the GI-system - Endocrine regulation
3B. What are the 7 hormones participating in endocrine regulation

Answer 17

1. CCK (cholecystokinin)
2. Gastrin
3. Secretin
4. GIP (gastric inhibitory peptide) / (glucose-dependent insulinotropic peptide)
5. Ghrelin
6. Aldosterone
7. Calcitriol

Question 18

II. Regulation of the GI-system - Endocrine regulation
3C. What are the functions of aldosterone and calcitriol?

Answer 18

Also aldosterone (Na+, K+) and calcitriol (↑ uptake of Ca2+-ions from lumen)

Question 19

II. Regulation of the GI-system - Endocrine regulation
3D. Fill in the gap - CKK

Answer 19

Question 20

II. Regulation of the GI-system - Endocrine regulation
3E. Fill in the gap - Gastrin

Answer 20

Question 21

II. Regulation of the GI-system - Endocrine regulation
3F. Fill in the gap - Secretin

Answer 21

Question 22

II. Regulation of the GI-system - Endocrine regulation
3F. Fill in the gap - GIP (gastric inhibitory peptide) / (glucose- dependent insulinotropic peptide)

Answer 22

Question 23

II. Regulation of the GI-system - Endocrine regulation
3G. Fill in the gap - Ghrelin

Answer 23

Question 24

II. Regulation of the GI-system - Paracrine regulation
4A. What are the features of paracrine regulation?

Answer 24

A regulatory substance will be released from a sensor cell and act on a nearby target cell.

Question 25

II. Regulation of the GI-system - Paracrine regulation
4B. What are the 3 paracrine mediators?

Answer 25

1. Serotonin (5-HT)
2. Histamine
3. Somatostatin

Question 26

II. Regulation of the GI-system - Paracrine regulation
4C. Fill in the gap - Serotonin

Answer 26

Question 27

II. Regulation of the GI-system - Paracrine regulation
4D. Fill in the gap - Histamine

Answer 27

Question 28

II. Regulation of the GI-system - Paracrine regulation
4E. Fill in the gap - Somatostatin

Answer 28