Lecture 3-Physiology

Question 1

Which spinal divisions are part of the sympathetic innervation to the GI tract?

Answer 1

T5-L3

Question 2

Which spinal divisions form the greater splanchnic nerve?

Answer 2

T5-9

Question 3

Which spinal divisions form the lesser splanchnic nerve?

Answer 3

T10-11

Question 4

Which spinal division forms the least splanchnic nerve?

Answer 4

T12

Question 5

True or false: sympathetic innervation in the GI tract mainly innervates blood vessels

Answer 5

TRUE

Question 6

Which nerve provides the major parasympathetic innervation to the GI tract?

Answer 6

Vagus nerve

Question 7

True or false: left vagus nerve becomes posterior and right vagus nerve becomes anterior as the foregut rotates

Answer 7

FALSE - other way round

Question 8

Which part of the GI tract do the parasympathetic fibres innervate?

Answer 8

Smooth muscle, endocrine and secretory parts

Question 9

True or false: the enteric nervous system can operate independently of the ANS

Answer 9

TRUE

Question 10

What are the two main plexuses of the enteric nervous system?

Answer 10

1) submucosal (Meissner’s)

2) myenteric (Auerbach’s)

Question 11

Give an example of a paracrine peptide and state where it’s found and what it does

Answer 11

• Somatostatin
• D cells in antrum of stomach and pancreas
• Stimulated by H+ in stomach and inhibits G cells and histamine release

Question 12

Give an example of a neurocrine peptide, where it is found and what it does

Answer 12

• Gastrin releasing peptide (GRP)
• Released by vagus nerve
• Increases release of gastrin from G cells

Question 13

What are the two families of GI hormones?

Answer 13

Gastrin family

Secretin family

Question 14

What are the two hormones in the GI family?

Answer 14

Gastrin

Cholecystokinin

Question 15

What does gastrin bind to and what does it do?

Answer 15

CCK receptor

Increases gastric acid secretion

Question 16

Which cells produce cholecystokinin (CCK) and where?

Answer 16

I cells in duodenum and jejunum

Question 17

What does CCK do?

Answer 17

Increases pancreatic/gallbladder secretions

Relaxes muscular sphincter where biliary tree enters 2nd part of duodenum

Question 18

What stimulates CCK?

Answer 18

Fat and protein

Question 19

Which two hormones are in the secretin family?

Answer 19

Secretin

Gastric inhibitory peptide (GIP)

Question 20

Which cells produce secretin and where?

Answer 20

S cells in duodenum

Question 21

What stimulates secretin?

Answer 21

H+ and fatty acids

Question 22

What does secretin do?

Answer 22

Increases HCO3-

Decreases gastric acid

Question 23

Where is GIP produced?

Answer 23

Duodenum and jejunum

Question 24

What stimulates GIP?

Answer 24

Sugars
AA
Fatty acids

Question 25

What does GIP do?

Answer 25

Increases insulin | Decreases gastric acid

Question 26

Where can pain in foregut structures be felt?

Answer 26

Epigastric region

Question 27

Where can pain in midgut structures be felt?

Answer 27

Periumbilical region

Question 28

Where can pain in hindgut structures be felt?

Answer 28

Suprapubic region

Question 29

What is peristalsis?

Answer 29

Propulsion of contents in one direction

Question 30

What is segmentation?

Answer 30

Contraction splits contents then relaxes, mixes contents

Question 31

What is paralytic ileus?

Answer 31

Loss of GI contractility

Question 32

What is achalasia?

Answer 32

Failure of LOS to relax -> dysphagia

Question 33

What is Hirschsprung’s disease?

Answer 33

Lack of myenteric/submucosal plexuses

Question 34

What are the major types of GI secretions and what are their functions?

Answer 34

- stomach acid: protein digestion, activates enzymes, infection barrier - HCO3-: neutralise food - emulsifiers: bile salts to increase SA of lipids - mucus: lubrication, protects against acidity of stomach, protects against bacteria in SI, harbours bacteria in LI - enzymes: to break down protein, fat and carbs