Gastro Flashcards
What cells secrete gastrin?
G cells in antrum of stomach
What stimulates gastrin secretion from G cells in antrum?
Gastric distension.
Amino acids in the antrum.
What does gastrin do?
Acid secretion
Secretion of peptin, gastric acid and intrinsic factor.
What cells secrete secretin?
S cells in duodenum/ jejunum/ SI
What activates secretin?
What are its actions
Acid in small bowel.
Delays gastric emptying.
Pancreatic bicarbonate secretion.
What stimulates secretion of CCK-PZ?
Fat, amino acids and peptides in the small bowel
What are the actions of CCK-PZ?
Pancreatic enzyme secretion.
Gallbladder contraction.
Delays gastric emptying
What are the actions of gastric inhibitory peptide?
Inhibits gastric acid secretion.
Stimulates insulin secretion.
Reduces mobility
Name three gastric hormones that reduce acidity
Where in body are they secreted from
CCK
Secretin
GIP
Duodenum, jejunum, SI
What cells secrete somatostatin
D cells in pancreasW
What activates somantostatin release
Vagal and adrenergic stimulation
What is role of somatostatin
Inhibits gastrin and pancreatic secretion
What hormones stimulates release of bile from gallbladder?
CCK
4 factors that increase iron absorption?
Increased erythropoesis eg pregnancy
Decreased body iron
Vitamin C
Gastric acid (latter two by converting Fe3+–>Fe2+)
4 factors that decrease iron absorption
Gastrectomy
Small bowel disease
Some medications
Low levels of HCl
Describe B12 absorption
B12 is ingested, binds to instrinsic factor in the stomach and is absorbed in the terminal ileum
Briefly describe the pathophysiology of pernicious anaemia
Autoantibodies against intrinsic factor and gastric parietal cells.
ABs against instrinsic factor block B12 receptors.
ABs against parietal cells reduce acid production, leading to atrophic gastritis and reduced IF production.
Only way to test for H. Pylori eradication?
Urea breath test
Eradication for H. Pylori? How long for?
PPI
Amoxicillin
Clari/ metro.
If pen allergic, no amox, both clari and metro
1 week
In H.Pylori -ve dyspepsia, how long should you prescribe PPI for?
4 weeks
Name 4 conditions associated with H. Pylori. Which has strongest association
Peptic ulcers
B cell lymphoma MALT tissue
Atrophic gastritis
Gastric cancer
How long need to be off abx and PPI before checking for H. Pylori
4 weeks off abx
2 weeks off PPI
Brief pathophysiology of zollinger-ellison syndrome?
Gastrin secreting adenocarcinoma (usually in pancreas or small intestine) leads to multiple GI ulcers.
How is zollinger-ellison initially diagnosed
High fasting serum gastrin levels over 3 different days.
Increased secretin can also be useful
Management of zollinger-ellison
High dose PPI
Resection if possible
Somatostatin analogue to reduced gastric secretion
MOA octerotide. When may it be used?
Somatostatin analogue
Zollinger-ellison, anecdotal evidence for dumping syndrome
Pathophysiology of early onset dumping syndrome
Within 1/2 hour of eating
Vagally mediated response to gastric emptying
Pathophysiology late onset dumping syndrome
1-3 hours.
Rebound hypoglycaemia following hyperglycaemia caused by carbs in small intenstine
What may be found on biopsy of gastric carcinoma
Signet cells
True or false- more signet cells= worse prognosis of gastric cancer
True.
