4.1 Function of the Stomach Flashcards
What is receptive relaxation?
Vagally mediated relaxation of the orad region (fundus and upper body) which allows food to enter the stomach without raising the intragastric pressure. It prevents food reflux when swallowing.
What is peristalsis?
Coordinated contractions of the stomach to mix the stomach contents
What is ejected from the stomach and how regularly?
Chyme is ejected in liquid form at 3 ‘squirts’ a minute
Why is the stomach acidic?
To unravel proteins
Kill bacteria
Activates proteases
What cell releases HCl?
Parietal cell
What molecules stimulate parietal cells?
Gastrin, histamine and acetylcholine
Where is gastrin secreted from?
G cells
Where are G cells located?
The antrum of the stomach
What are G cells stimulated by?
Peptides in the stomach (Gastrin-releasing peptide (GRP)) Vagal stimulation (acetylcholine)
Where is histamine released from?
Enterochromaffin-like cell (ECL)
What cell releases pepsinogens?
Chief cells
What cells release somatostatin?
D cells
What molecule inhibits gastrin?
Somatostatin
What stimulates somatostatin to be released?
Low pH
How is HCl made in the gut?
Water is split into its ions
The H+ combines with Cl- in the stomach lumen. Cl- is moved out of parietal cells by swapping with HCO3-