gastrointestinal regulatory substances and secretory productsp. 380-381

Question 1

Gastrin: source?

Answer 1

G cells

Question 2

G-cells: produce what?

Answer 2

gastrin

Question 3

G-cells: where?

Answer 3

antrum of stomach (most lower part before pylorus), duodenom

Question 4

gastrin producing cells: where?

Answer 4

antrum of stomach (most lower part before pylorus), duodenom

(G-cells)

Question 5

gastrin: actions? (3)

Answer 5

gastric H+ secretion
growth of gastric mucosa
gastric motility

Question 6

gastric H+ secretion
growth of gastric mucosa
gastric motility

functions of which substance?

Answer 6

gastrin

Question 7

what increases gastrin secretion by g-cells? (3 things)

Answer 7

• stomach distention/alkalinization
• amino acids and peptides
• vagal stimulation via GRP (gastrin releasing peptide)

Question 8

what decreases gastrin secretion by g-cells?

Answer 8

pH < 1.5

Question 9

chronic use of which medication increase gastrin?

Answer 9

PPI

Question 10

chronic use of PPI increases what?

Answer 10

gastrin secretion

Question 11

which pathologies increase gastrin secretion? (2)

Answer 11

• chronic atrophic gastritis (H pylori)
• Zollinger-Ellison syndrome (gastrinoma)

gastrinoma is a gastrin-secreting tumor

Question 12

Zollinger-Ellison syndrome: increased secretion of what?

Answer 12

gastrin

Question 13

what is Zollinger-Ellison syndrome?

Answer 13

gastrinomas in pancreas or upper part small intestine -> produce gastrin -> too much acid -> peptic ulcers

rare

Question 14

chronic atrophic gastritis can lead to what?

Answer 14

overproduction of Gastrin

Question 15

Somatostatin: source?

Answer 15

D cells

Question 16

Where are D cells?

Answer 16

pancreatic islets, GI mucosa

Question 17

what do D cells produce?

Answer 17

somatostatin

Question 18

Effects of somatostatin? (4)

Answer 18

• less gastric acid and pepsinogen secretion
• less pancreatic and intestine fluid secretion
• less gallbladder contraction
• less insulin and glucagon release

Question 19

what leads to increased secretion of somatostatin?

Answer 19

more acid

Question 20

what leads to decreased secretion of somatostatin?

Answer 20

vagal stimulation

Question 21

what is octeotride?

Answer 21

a mimic of somatostatin

Question 22

which medication is the analog of somatostatin?

Answer 22

octeotride

Question 23

what can you treat with octeotride (mimic of somatostatin)? (4)

Answer 23

• agromegaly
• carcinoid syndrome
• VIPoma
• variceal bleeding

carcinoid tumor: neuroendocrine tumors

VIPoma: neuroendocrine tumor secreting vasoactive intestinal peptide (VIP) -> severe diarrhea

Question 24

cholecystokinin: which cells secrete this?

Answer 24

I cells

Question 25

where are I cells?

Answer 25

duodenum, jejunum

Question 26

I cells: secrete what?

Answer 26

cholecystokinin

Question 27

cholecystokinin: functions? (4)

Answer 27

- more pancreatic secretion - more gallbladder contraction - slows down gastric emptying - relaxes the sphincter of Oddi

Question 28

what increases cholecystokinin secretion?

Answer 28

fatty acids, amino acids

Question 29

fatty acids and amino acids increase secretion of what?

Answer 29

cholecystokinin

Question 30

via what pathways does cholecystokinin cause pancreatic secretion?

Answer 30

neural muscarinic pathways

Question 31

secretin: secreted via which cells?

Answer 31

S cells

Question 32

where are S cells?

Answer 32

duodenum

Question 33

what are the actions of S cells? (3)

Answer 33

- pancreatic HCO3 secretion - less gastric acid secretion - bile secretion

Question 34

what increases secretion of secretin

Answer 34

acid and fatty acids in lumen of duodenum

Question 35

acid and fatty acids in lumen of duodenum: increased secretion of what?

Answer 35

secretin

Question 36

what does HCO3 do in duodenum?

Answer 36

neutralizes gastric acid, allowing pancreatic enzymes to function

Question 37

glucose-dependent insulinotropic peptide: secreted by which cells?

Answer 37

K cells

Question 38

where are K cells?

Answer 38

duodenum, jejunum

Question 39

what do K cells secrete?

Answer 39

glucose-dependent insulinotropic peptide

Question 40

glucose-dependent insulinotropic peptide: exocrine functions?

Answer 40

less gastric acids secretion

Question 41

glucose-dependent insulinotropic peptide: endocrine functions?

Answer 41

insulin release

Question 42

what stimulates release of glucose-dependent insulinotropic peptide?

Answer 42

fatty acids, amino acids oral glucose

Question 43

glucose-dependent insulinotropic peptide: other name?

Answer 43

Gastric Inhibitory Peptide (GIP)

Question 44

what is the endocrine effect of oral glucose?

Answer 44

increases insulin, compared to IV equivalent due to glucose-dependent insulinotropic peptide/GIP secretion

Question 45

motilin: where is it secreted?

Answer 45

small intestine

Question 46

what is the effect of motilin?

Answer 46

it produces migrating motor complexes (MMCs)

Question 47

in which state is motilin more secreted?

Answer 47

in fasting state

Question 48

which hormone leads to migration motor complexes (MMCs)?

Answer 48

motilin

Question 49

which receptor agonist of which hormone are used to stimulate intestinal peristalsis?

Answer 49

motilin eg erythromicin

Question 50

Vasoactive intestinal peptide (VIP): source?

Answer 50

Parasympathetic ganglia in sphincters, gallbladder, small intestine

Question 51

Vasoactive intestinal peptide (VIP): what does it do?

Answer 51

- increases secretion of intestinal water and electrolytes - relaxes intestinal smooth muscles and sphincters

Question 52

what leads to more secretion of vasoactive intestinal peptide?

Answer 52

intestinal distension, vagal stimulation

Question 53

what leads to less secretion of vasoactive intestinal peptide?

Answer 53

adrenergic input

Question 54

what is a VIPoma?

Answer 54

pancreatic tumor that secretes VIP non-alpha, non-beta islet cells

Question 55

what is VIP?

Answer 55

vasoactive intestinal peptide

Question 56

what is a pancreatic tumor that secretes vasoactive intestinal peptide called?

Answer 56

VIPoma

Question 57

what do the parasympathetic ganglia in sphincters, gallbladder and small intestine secrete?

Answer 57

VIP (vasoactive intestinal peptide)

Question 58

which symptoms is VIPoma associated with?

Answer 58

Water Diarrhea, Hypokalemia, Achlorhydria (WDHA syndrome)

Question 59

Water Diarrhea, Hypokalemia, Achlorhydria what is this suggestive of?

Answer 59

VIPoma

Question 60

which part of the GI system does nitric oxide affect? what does it do?

Answer 60

LES, smooth muscle relaxation

Question 61

Loss of NO secretion. where is this implicated in the GI system?

Answer 61

higher LES tone in achalasia

Question 62

which substance is implicated in higher LES tone in achalasia?

Answer 62

NO

Question 63

what is achalasia?

Answer 63

failure of smooth muscle to relax, LES to remains closed

Question 64

Ghrelin: where is the source?

Answer 64

Stomach

Question 65

Ghrelin: what does it do?

Answer 65

increase the appetite ('ghrowlin' stomach)

Question 66

what does increase Ghrelin secretion?

Answer 66

fasting

Question 67

what lowers Ghrelin secretion?

Answer 67

eating food

Question 68

Prader-Willi: which hormone is increased?

Answer 68

Ghrelin

Question 69

Ghrelin: implicated in which syndrome?

Answer 69

Prader-Willi

Question 70

after what type of surgery is Ghrelin decreased?

Answer 70

gastric bypass

Question 71

gastric bypass surgery affects which hormone that causes appetite?

Answer 71

Ghrelin

Question 72

gastric acid: source?

Answer 72

parietal cells in the stomach

Question 73

gastric acid: what does it do?

Answer 73

decrease the pH of the stomach (make it more acid)

Question 74

how is gastric acid and intrinsic factor increased?

Answer 74

histamine, vagal stimulation, gastrin

Question 75

intrinsic factor: source?

Answer 75

Parietal cells in the stomach

Question 76

intrinsic factor: what does it do?

Answer 76

binds to Vitamin B12, this is required for uptake in the terminal ileum

Question 77

how is gastric acid and intrinsic factor decreased?

Answer 77

somatostatin, GIP, prostaglandin, secretin

Question 78

what does autoimmune destruction of parietal cells lead to?

Answer 78

chronic gastritis, pernicious anemia

Question 79

what is pernicious anemia?

Answer 79

B12 deficiency and megaloblastic anemia

Question 80

pepsin: source?

Answer 80

chief cells in the stomach

Question 81

what does pepsin do?

Answer 81

protein digestion

Question 82

what leads to increased secretion of pepsin?

Answer 82

vagal stimulation (ACh), local acid

Question 83

what is pepsinogen?

Answer 83

the inactive form of pepsin

Question 84

when does pepsinogen converted into pepsin?

Answer 84

in the presence of H+

Question 85

bicarbonate: source?

Answer 85

mucosal cells (stomach, duodenum, salivery glands, pancreas) Brunner glands (duodenum)

Question 86

what does bicarbonate do?

Answer 86

neutralizes acid

Question 87

what leads to increased secretation of bicarbonate?

Answer 87

pancreatic and biliary secretion with secretin

Question 88

where is bicarbonate trapped?

Answer 88

in mucus that covers the gastric epithelium