Gatric motility and secretions II Flashcards
Describe the interdigestive phase of the gastric acid secretions.
This phase is lowest in the morning and rises through the day.
The pH can vary from 3-6 depending on #parietal cells, body weight, or food in the stomach.
Describe the Cephalic phase of the gastric acid secretions
Accounts for 30% of the acid secretion.
Activated by stimuli such as sight or smell of food.
Vagal response causes the acid release.
Describe the Gastric phase of the gastric acid secretions.
Accounts for 50-60% of acid secretion.
Stimulated by vagal tract in response to stomach distension.
Protein products in stomach trigger as well.
If pH drops below 1 acid secretion inhibited by gastric D cells through feedback loop.
Describe the intestinal phase of the gastric acid secretions
Accounts for 10% of gastric acid secretion.
Mediated by presence of peptides in the duodenum.
Peptides induce gastrin release increasing parietal cell activity.
Where is intrinsic factor released from?
Released from parietal cells!
What is the function of intrinsic factor?
In order for the body to absorb Vitamin B12 the parietal cells must release intrinsic factor that complexes with vitamin B12 in the duodenum.
This allows it to be absorbed via receptor mediated endocytosis.
Describe the function of pepsinogen
Pepsinogen is released via chief cells primarily by Ach.
It is cleaved in the stomach to pepsin where it is then able to initiate protein digestion.
What are the two mechanisms by which the stomach is able to protect itself from the low pH
Release of mucous and HCO3- from epithelial and neck cells stimulated by acetylcholine and prostaglandins.
How can aspirin lead to gastric ulcers?
It inhibits COX which is the key maker of prostaglandins!
Without prostaglandins there is a decrease in the production of HCO3- and mucus.
What is zollinger-ellison syndrome?
High serum gastrin levels leading to posible peptic ulcers!
