Alkali: A chemical that has a pH of more than 7 and neutralizes or buffers acids. They are typically caustic or corrosive.
Acid: A substance that is corrosive, sour-tasting and having a pH of less than 7
Esophagus: The muscular tube through which food passes from the throat to the stomach.
Lower esophageal sphincter: A muscular ring that surrounds the lower part of the esophagus and connects it to the opening of the stomach. It is meant to open only to let the contents to go from esophagus to the stomach and not backwards.
pH level: Short for “potential of hydrogen”, is a numeric scale with reference to water, that is used to specify the acidity or alkalinity of an aqueous solution.
Peptide bonds: A chemical bond combining two consecutive amino acid monomers to a protein chain.