Unit 12

Question 1

What are the 2 types of electrical activity in gastrointestinal smooth muscle?

Answer 1

Slow waves
Spikes

Question 2

Which intestinal cells act as electrical pacemakers?

Answer 2

Interstitial cells of Cajal

Question 3

How do ion channels in GI smooth muscle differ from nerve cells?

Answer 3

Channels responsible for action potentials predominantly allow calcium ions to enter with a smaller amount of sodium - calcium-sodium channels
Slower to open and close

Question 4

What factors can alter the resting potential of GI smooth muscle?

Answer 4

Depolarised by:
Stretch
ACh stimulation
Stimulation by GI hormones

Hyperpolarised by:
NEp and Ep
Stimulation of sympathetic nerves

Question 5

Describe the structure of the enteric nervous system

Answer 5

Myeneteric plexus - between longitudinal and smooth muscle layers - GI movement
Submucosal plexus - in submucosa - secretions and blood supply

Question 6

Which nerves supply the parasympathetic input to the GIT?

Answer 6

Cranial - vagus
Caudal - pelvic

Question 7

Where is gastrin secreted?

Answer 7

G cells of stomach

Question 8

What stimulates gastrin secretion?

Answer 8

Stomach distension
Products of protein digestion
Gastrin-releasing peptide - released during vagal stimulation

Question 9

What are the actions of gastrin?

Answer 9

Gastric acid secretion
Gastric mucosal growth

Question 10

Where is CCK secreted?

Answer 10

I cels of duodenum and jejunum

Question 11

What stimulates CCK secretion?

Answer 11

Digestive products of fat

Question 12

What action does CCK have?

Answer 12

GB contraction
Inhibits stomach contraction
Inhibits appetite

Question 13

Where is secretin released?

Answer 13

S cells - duodenum

Question 14

What stimulates secretin release?

Answer 14

Acidic gastric juice entering duodenum

Question 15

What are the effects of secretin?

Answer 15

Promotes bicarbonate secretion
Mild effect on motility

Question 16

Where is glucose-dependent insulinotropic peptide (GIP) released?

Answer 16

K cells of mucosa of upper small intestine

Question 17

What stimulates GIP release?

Answer 17

Fatty acids and amino acids

Question 18

What are the effects of GIP?

Answer 18

Slows gastric emptying into duodenum. Reduces secretion of gastric acid
Stimulates insulin secretion

Question 19

Where is motion secreted?

Answer 19

M cells. Stomach and upper duodenum

Question 20

What stimulates motion secretion?

Answer 20

Fasting

Question 21

What is the action of motilin?

Answer 21

Stimulates interdigestive myoelectric complexes

Question 22

Which GI hormones have a vasodilator effect?

Answer 22

CCK, VIP, gastrin, secretin

Question 23

What 3 factors increase local GI blood flow?

Answer 23

Hormones
Kinins - kalliidn and bradykinin
Reduced oxygen concentration

Question 24

What is the main promotor of gastric emptying?

Answer 24

Gastrin

Question 25

What neurological factors inhibit stomach emptying?

Answer 25

Enterogastric reflex - directly to stomach through enteric nervous system - through extrinsic nerves via pre vertebral sympathetic ganglia - through vagus nerve to brainstem

Question 26

What factors activate the enterogastric inhibitory reflex?

Answer 26

Distension of duodenum Irritation of duodenal mucosa Acidity of duodenal chyme Osmolality of the chyme Presence of protein in chyme

Question 27

What hormone inhibits gastric emptying?

Answer 27

CCK Secretin and GIP to lesser extent

Question 28

What hormones increase intestinal peristalsis?

Answer 28

Gastrin, CCK, insulin, motilin, serotonin

Question 29

What hormones inhibit small intestinal motility?

Answer 29

Secretin and glucagon

Question 30

What nerves are responsible for a) conscious and c) unconscious control of defecation?

Answer 30

a) Pudendal b) Pelvic

Question 31

Are anaerobic/aerobic bacteria more common in the lower intestine?

Answer 31

Anaerobic

Question 32

What are the predominant cells in the a) body, b) fundus and c) antrum of the stomach?

Answer 32

a) Mucus neck cells, parietal cells, chief cells b) Enterochromaffin-like cells, somatostatin-producing cells c) Gastrin and somatostatin-producing cells

Question 33

What stimulates gastrin release?

Answer 33

Luminal peptides, digested protein, acetylcholine, gastrin-releasing peptide

Question 34

What stimulates gastric acid secretion?

Answer 34

Gastrin, histamine, acetylcholine

Question 35

What stimulates somatostatin release? How does it affect the stomach?

Answer 35

pH <3 Reduces gastrin, histamine and acid secretion

Question 36

What acid-base abnormalities are seen in combination with vomiting?

Answer 36

Metabolic acidosis - most common Metabolic alkalosis - when gastric outflow/proximal duodenum obstructed

Question 37

In what situations is metabolic alkalosis recognised in patients with GI signs?

Answer 37

Outflow obstruction, CPV, pancreatitis, gastrinoma

Question 38

DDX elevated gastrin and low gastric pH?

Answer 38

Gastrinoma Hepatic/renal disease

Question 39

How is gastrinoma diagnosed?

Answer 39

Elevated gastrin + low gastric pH Gastrin measurement following secretin or Ca infusion

Question 40

How is achlorhydria diagnosed?

Answer 40

Elevated gastrin and gastric pH >3 Pentagastrin or bombesin stimulation

Question 41

What does a metabolic alkalosis, hypochloraemia, hypokalaemia and acidic urine suggest?

Answer 41

Upper GI obstruction or hypersecretory state

Question 42

Where are NSAID-related ulcers most often found?

Answer 42

Antrum

Question 43

How is gastrinoma medically managed?

Answer 43

Omeprazole + somatostatin analogue (eg octreotide)

Question 44

What is a potential treatment for large gastric ulcers?

Answer 44

Octreotide

Question 45

Metoclopramie MOA

Answer 45

Antagonises D2-dopaminergic and 5ht3-serotonergic receptors Cholinergic effect on smooth muscle

Question 46

Ondansetron MOA

Answer 46

Peripheral 5HT3 antagonism

Question 47

Maropitant MOA

Answer 47

NK-1 antagonist

Question 48

What is the risk of maropitant in dogs <8 weeks old

Answer 48

Bone marrow hypoplasia described

Question 49

What parasites are associated with gastritis? What species do they infect?

Answer 49

Ollulanus Tricuspis - cats Physaloptera - cats and dogs

Question 50

How is ollulanus tricuspis spread? How is it diagnosed/treated?

Answer 50

Cat to cat - ingestion of vomitus/autoinfection Evaluation of gastric juice, vomit or histo Fenbendazole

Question 51

What stain is used to confirm pythosis?

Answer 51

Gomori's methenamine silver

Question 52

How does gastric pythosis present?

Answer 52

Thickening of gastric outflow tract

Question 53

How is gastric pythosis treated?

Answer 53

Aggressive resection Itraconazole and terbinafine for 2-3 months

Question 54

In which breed has atrophic gastritis been described?

Answer 54

Lundehund

Question 55

What enzyme is responsible for the majority of carbohydrate digestion?

Answer 55

Pancreatic amylase

Question 56

Where does the majority of protein digestion occur?

Answer 56

Upper small intestine - pancreatic enzymes

Question 57

Which cranial nerves are involved in swallowing?

Answer 57

V, IX, X