Antacids and the pH Balance in Your Stomach

The inside lining of the stomach is made up of parietal cells, which are fused together to form tight junctions. The interiors of the cells are protected from the surroundings by cell membranes. These membranes allow water and neutral molecules to pass in and out of the stomach, but they usually block the movement of ions such as H, Na, K, and Cl . The ions come from carbonic acid (H2CO3) formed as a result of the hydration of CO2, an end product of metabolism  

These reactions take place in the blood plasma bathing the cells in the mucosa. By a process known as active transport, ions move across the membrane into the stomach interior. (Active transport processes are aided by enzymes.) To maintain electrical balance, an equal number of Cl ions also move from the blood plasma into the stomach. Once in the stomach, most of these ions are prevented by cell membranes from diffusing back into the blood plasma. 

One way to temporarily reduce the ions concentration in the stomach is to take an antacid. 

The major function of antacids is to neutralize excess HCl in gastric juice. The following table lists the active ingredients of some popular antacids. The reactions by which these antacids neutralize stomach acid are as follows  

Active Ingredients in Some Common Antacids Commercial Name Active Ingredients  

The purpose of the highly acidic medium within the stomach is to digest food and to activate certain digestive enzymes. Eating stimulates ion secretion. A small fraction 

The alkali and alkaline earth metal hydroxides [except for Be(OH)2] have basic properties. The following hydroxides are amphoteric Be(OH)2, Al(OH)3, Sn(OH)2, Pb(OH)2, Cr(OH)3, Cu(OH)2, Zn(OH)2, and Cd(OH)2. For example, aluminum hydroxide reacts with both adds and bases  

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