Gastro Flashcards
Where is the vomiting centre located in the brain?
Medulla oblongata
Give some examples of trigger points that lead to vomiting:
Labyrinth receptors in ear (eg motion sickness)
Over distension of the gut and stomach
Trigger zone in the CNS (e.g. medications)
Touch receptors in throat i.e. gag point
Give an example of a medication that can increase gastric emptying and decreases GI transit time?
Erythromycin
List the phases of gastric acid secretion:
1) Cephalic phase
2) Gastric phase
3) Intestinal phase
How much of the acid is produced during the cephalic phase?
30%
What happens during the cephalic phase?
Smell / taste of food
Vagal cholinergic stimulation leads to secretion of HCL and gastric from G cells
What cells are gastrin and HCL released from
G cells
What occurs during the gastric phase of of acid secretion?
Stomach distension and low H+ ions
Leads to production of gastrin
How much acid is produced during the gastric phase?
60%
How much acid is produced during the intestinal phase?
10%
Where is the foot in the intestinal phase?
The duodenum
What happens to gastric acid secretion during the intestinal phase?
It becomes inhibited by CCK and secretin.
List some factors which increase production of gastric acid:
Vagal nerve stimulation
Gastrin release
Histamine release
What cells in the stomahc release histamine?
Enterchromaffin like cells
List some factors which decrease gastric acid secretion:
Somatostatin
Cholecystokinin
Secretein
What cells produce cholecystokinin (CCK) and where are they located
I cells of the upper small intestine
List some of the actions of CCK?
- Decreases gastric acid secretion
- Contracts gallbladder
- Relaxes sphincter of Oddi
- Decreases gastric emptying
- Induces satiety
Where are G cells located
Antrum of the stomach
Gastrin increases gastric motility. True or False
True
What cells release secretin?
S cells
Where are S cells located?
The upper small intestine
List some of the actions of secretin:
- Stimulates secretions by the pancreas and intestines
- Inhibits acid and pepsinogen secretion
What cells produce somatostatin?
D cells
Where are D cells located?
Pancreas and Stomach
List the actions of somatostatin:
- Decrease acid and pepsin secretion
- Decrease gastric secretion
- Decrease pancreatic enzyme secretion
- Decrease insulin and glucagon secretion
- Inhibits trophic effects of gastrin
- Stimulates gastric mucus production
What inhibits gastrin secretion?
Low antral pH
Somatostatin
List the actions of gastrin:
- Increases HCL
- Increases IF secretion
- Increase gastric motility
- Trophi effect on gastric mucose
What cell produces gastric acid?
Parietal cells
What is the normal pH of the stomach?
2
What is responsible for maintaining the pH / acidity of the stomach?
H+ / K+ ATPase pump
Where is bicarbonate secreted during gastric acid secretion?
Into the surrounding vessels via the H+K+ ATPase plant.
Where do parietal cells secrete sodium and chloride?
into the canaliculus
What maintains the pH of the stomach
The H+/K+ ATPase pump
Which of the following would inhibit gastric acid secretion:
- Nausea
- Vagal / parasympathetic stimulation
- Calcium
- Histamin
Nausea - works via higher cerebral activity and sympathetic innervation
Release of which hormone will be directly impacted by a truncal vagotomy?
Gastrin
What part of the GI tract is responsible for the majority of water absorption?
Jejunum
Where in the gut is iron absorbed most?
Duodenum
What do foveolar cells secrete?
Mucus to protect gastric mucosa
