D4 pH regulation of the stomach Flashcards
why is it necessary to regulate pH of the stomach?
changes in H+ conc influences activity of many molecules esp enzymes
describe the acidity of the stomach
low pH levels of 1-2 thru prod. of gastric juice containing HCl (aq) : released from parietal cells in gastric glands in stomach wall lining
what does the acidic enviro of stomach do 2
- kill ingested bacteria
- provide optimum conditions for activity of digestive enzymes
what factors can cause excess production of gastric juices
alcohol
smoking
caffeine
stress
impacts of excess prod of gastric juices
- acid indigestion = discomfort
- heartburn/ acid reflux = acid rising to esophagus
- ulceration = damage to gut wall lining = loss of tissue, inflammation
what impacts of excess gastric juice does dysepsia encompass
- acid indigestion = discomfort
- heartburn / acid reflex = acid rising
3 types of drugs that help prevent excess acid production
- antacids
- H2-receptor antagonists
- proton pump inhibitors
how do antacids work
- reacts with and neutralises HCl
- usually weak basic compounds (not strong – caustic)
antacid formulae to know
metal hydroxide + hcl = salt + water
metal carbonate/bicarbonate + hcl = salt + water + gas
Al vs Mg in antacids
dissolve slower, longer relief // faster acting
constipation // laxatives
how do antacids affect drug absorption
they change stomach pH
how is bloating from gas release (antacids) mitigated
antifoaming agents added
(some contain alginates – float to top of stomach to prevent reflux)
what are H2 receptor antagonists
drugs preventing interaction betw histamine and H2 (NOT h2 gas)
- compete with histamine for binding at H2 receptors
- histamine (hormone) stimulates stomach acid secretion
- interaction happens in parietal cells in gastric glands
H2 receptor antagonists example
ranitidine (zantac)
what are proton pump ihibitors
drugs inhibiting proton pump = directly preventing release of stomach acid
