LECTURE 21: GI Flashcards
GI system
digests the macromolecules present in food into simpler molecules that can be absorbed
3 types of cells found in gastric glands
pareital, chief, goblet cells
gastric acid secretion is controlled by
Ach, histamine, prostaglandin I2 and E2
damage by production of inappropriate gastric juices leads to
minor GERD and major peptic ulcers disease
GERD
when stomach and duodenum contents backflow into oesophagus causing inflammation of oesophageal mucosa
peptic ulcers
ulcer in area where the mucosa is saturated in HCl and pepsin of gastric juice
peptic ulcers - where?
stomach and upper duodenum
drugs for GERD and peptic ulcers
- antacids
- PPI
- H2 receptor antagonist
- M1 musc inhibitor
- Misoprostol
- mucosal strengtheners
antacids
alkaline substances that neutralize stomach acid, increasing pH so stomach can repair
PPI
irreversibly inhibit the H-K-ATPase proton pump that controls H+ secretion from parietal cells reducing gastric acid production
omeprazole
H2 receptor antagonist
block H2 histamine receptors, decrease gastric acid secretion from parietal cells to reduce stomach acidity
M1 muscarinic receptor antagonist
- Some M1 muscarinic blockers, such as hyoscyamine can inhibit gastric acid secretion
- Acetylcholine facilitates ‘rest and digest’ state, which increases stomach acid secretion; hence blocking this neurotransmitter can inhibit this effect
misoprostol
- A synthetic analogue of prostaglandin E1 that binds to E1 G-protein coupled receptors on parietal cells, inhibiting adenyl cyclase and decreasing cAMP, blocking acid production
- Not a first line treatment- less effective than PPIs or H2 blockers
mucosal strengtheners
- These are poorly soluble molecules that polymerise in the acid environment of the stomach
- The polymer then binds to the damaged tissue and forms a protective coating over the ulcer beds
- Used to treat acute ulcers as well as prevent reoccurrence
