pH Regulation of Stomach Acid Flashcards
antacids
an immediate and effective relief for issues stemming from excess stomach acid
what must antacids have?
must contain a weak base to neutralise HCl in the stomach
frequently contained in antacids
calcium carbonate, magensium hydroxide, sodium carbonate, calcium hydroxide, sodium bicarbonate
buffering action of stomach
stomach produces a regulated (pH: 1-3) amount of acid in response to food indigestion
buffers
solutions that resist changes in pH when small amounts of strong acids or strong bases are added
relation between pH and equilibrium
- if pH is low due to releasing too much acid, EQ shifts left to use up excess acid
- if pH is high due to acid used up in digestion, EQ shifts right to replenish acid
agonist
a substance that binds to a receptor and fully activates it (e.g. opiates)
antagonist
binds to a receptor and blocks it or prevents the action of other agonists (e.g. aspirin)
ranitidine (zantac)
reversibly binds with the histamine receptor and blocks its action so that acid will not be produced by the cells where ranitidine interferes with the histamine receptor
why doesn’t ranitidine have an immediate effect?
because there is a time delay for the liver to metabolise the drug before it is active
proton pump inhibitors
irreversibly binding to the proton pump with a covalent bond, preventing it from pumping hydrogen ions into the stomach
bioavailability of omeprazole
has many polar functional groups which ensure high bioavailability when orally ingested (but takes a while for effect to settle in)
why are PPIs more effective than H2 receptors
the active metabolite binds covalently to the proton pump, resulting in a longer-lasting effect compared to ranitidine
