04.1 Functions of the Stomach Flashcards
What does the stomach do upon receiving food?
Dis tends
How does the stomach distend?
Rugae allow expansion
Relaxation via the vagus nerve
How does the stomach disrupt food?
Peristalsis mixes
Smaller contents accelerate forwards due to shape but lumps left behind.
What is the function of acid in the stomach?
Converts pepsinogen to pepsin
Disinfects the contents
What do parietal cells release?
Hydrochloric acid
Intrinsic factor
What do chief cells release?
Pepsinogen
What do g cells secrete?
Gastrin
What do enterochromaffin like cells secrete?
Histamine
What do d cells secrete?
Somatostatin
What increases parietal cell activity?
Vagus nerve
Histamine from ECL
Gastrin from g cells
What stimulates gastrin release?
Peptides and amino acids
Vagal stimulation
What inhibits g cells?
Somatostatin from d cells
What is the mechanism that inhibits acid production?
1-When food leaves, pH falls.
Low pH activates d cells to secrete somatostatin.
Somatostatin inhibits g cells and ECL cells (which usually stimulate parietal cells)
2-Stomach distension reduces
This leads to reduced vagal activity
What are 4 defences the stomach has against damage?
Mucus layer
Alkaline HCO3
High turnover of cells
Prostaglandins which maintain mucosal blood flow
What can breach these stomach defences?
Alcohol dissolves mucus
Helicobacter pylori
NSAIDs (inhibit prostaglandin)
