Gastrointestinal Flashcards
When does the intestinal phase occur?
The intestinal phase of gastric secretion occurs when the duodenum responds to the arriving chyme. 5%–10% of gastric secretion occurs during this phase.
What happens during the intestinal phase?
Two things occur simultaneously: duodenal stimulation and duodenal inhibition.
What causes duodenal stimulation in the intestinal phase?
Duodenal stimulation occurs when partially digested protein enters the duodenum, and the duodenum responds by stimulating gastric secretion.
What causes duodenal inhibition in the intestinal phase?
Duodenal inhibition is stimulated by acid and fat in the duodenal lumen. Many systems and substances take part in this inhibition, such as the neural system and hormones (secretin, cholecystokinin, gastric inhibitory peptide). Duodenal inhibition inhibits gastric secretion and motility.
What is pancreatic polypeptide?
Pancreatic polypeptide is a 36-amino acid peptide secreted from the F (pancreatic polypeptide) cells of the pancreas especially at the head of pancreas.
What is the function of pancreatic polypeptide?
It acts as a satiety hormone, with suppression of exocrine pancreatic secretion and a slowing of gastric emptying. It has many functions in the gastrointestinal tract, e.g. it inhibits intestinal motility and increases the secretion of gastrointestinal enzymes.
What stimulates the release of pancreatic polypeptide?
Pancreatic polypeptide secretion is stimulated by fasting, protein meals, hypoglycaemia and exercise
What inhibits the release of pancreatic polypeptide?
intravenous glucose, hyperglycaemia, somatostatin and atropine.
What causes receptive relaxation of the stomach?
Normally, when food stretches the stomach, a “vasovagal reflex” is sent to the brain stem and then back to the stomach reduces the tone in the muscular wall of the stomach body causing receptive relaxation
What leaves the stomach first- fat, carbohydrate or proten?
Carbs followed by protein then fat
Which hormones inhibit gastric emptying?
The hormones cholecystokinin and secretin have inhibitory effects on gastric emptying. They inhibit the pyloric pump and, at the same time, increase the strength of contraction of the pyloric sphincter
Which hormone increases gastric emptying?
Gastrin strengthens antral contractions against the pylorus and relaxes the pyloric sphincter which increases the rate of gastric emptying.
At what rectal pressure does the urge to defecate occur?
18mmHg
At what pressure does the internal sphincter relax?
55mmHg
What nerve controls the external anal sphincter?
Pudendal nerve, S2-4 anterior division
