Gastric acid: A digestive fluid formed in the stomach, composed of hydrochloric acid (HCl), potassium chloride (KCl), and sodium chloride (NaCl) which helps break down and digest food.
Stomach lining: The inner layer of the stomach which contains glands that produce stomach acid and enzymes necessary for digestion.
Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs