4. pH regulation of the stomach

Antacids reduce excess stomach acid by neutralization. HCl in stomach kills bacteria and provides optimum pH Excess HCl causes acid indigestion, heartburn and ulcers

Must be a weak base (strong are harmful) CaOH2 + 2HCl => CaCl2 + 2H2O MgOH2 + 2HCl => MgCl2 + 2H2O AlOH3 + 3HCl => AlCl3 + 3H2O Na2CO3 + 2HCl => 2NaCl + CO2 + H2O NaHCO3 + HCl => NaCl + CO2 + H2O

Alginates - Creates a neutralising layer - Prevents acid rising into the oesophagus Dimethicone (anti-foaming agent) - Prevents bloating and flatulence

Relieve acid reflux, heartburn and indigestion 1) Proton Pump Inhibitors (PPI) 2) H2 Receptor Antagonists / Blocker PPIs inhibit whilst Antacids neutralise. PPIs have a much longer lasting effect than antacids.

Omeprazole Gastric Proton Pumps pump H+ in the stomach PPI Inhibits the pump, and prevents release of the protons. Longer lasting effect (3 days) They’re used to treat stomach ulcers and provide relief from symptoms of acid reflux

Ranitidine Histamine stimulates secretion of stomach acid by interacting with H2 receptors in the lining of the stomach H2 blockers compete with histamine to bind with the receptors, blocking histamine. H2 receptor antagonist example: Ranitidine

Hendersson-Hasselbalch equation pH = pKa + log10 ([A-] / [HA]) Where [A-] = initial concentration of the salt Where [HA] = initial concentration of the weak acid.

1st assumption Weak acids only partially dissociate and not much, so it’s assumed that the [HA]initial = [HA]final 2nd assumption Salt fully dissociates within the solution so that initial [A-] concentration is the same as [AB]