What Are Acids and Bases

The world is filled with acids and their counterparts, bases. These substances are in our foods and beverages, as well as throughout nature. An acid is any molecule that has the potential to release a hydrogen ion (H+) when mixed into a water-based fluid. A hydrogen ion is a hydrogen atom that breaks away from a molecule but in the process leaves an electron behind. Because it has lost an electron, it will have a positive charge and because it has a positive charge, it easily dissolves into water.

When an acid is added to water, the hydrogen-ion content of the water will increase. On the other hand, a base is any substance that when dissolved in water will take up hydrogen ions from the fluid. Simply stated, an acid will increase the hydrogen ion content of a water-based fluid whereas a base will decrease it. Therefore, acids and bases are opposites.

We often indicate the level of acidity or alkalinity (basicity) to refer to the amount of hydrogen ions dissolved in water or a water-based fluid. Our body can be considered a container of water-based fluid, and, as will soon become more obvious, the concentration of hydrogen ions in our body fluid will greatly influence function and health.

How Do We Measure Acidity or Alkalinity?

Acidity and alkalinity indicates the level of hydrogen ions in a water-based fluid and we use the pH scale to assess a fluid. The pH scale ranges from 0 to 14, with 0 being the most acidic and 14 being the most basic as shown in Figure 1.9. Thus, a pH of 7 is said to be neutral because it splits the two extremes. A pH lower that 7 means a higher hydrogen ion concentration and thus greater acidity. On the other hand, an alkaline solution has a pH greater than 7 and has a lower level of hydrogen ions.

The pH scale was conceived by Soren Sorensen who was a pretty good biochemist and an excellent brewer of beer! Back in the days before sophisticated pH meters, one could speculate as to whether a fluid was acidic or basic based on taste. Acidic substances tend to have a sour taste (lemon juice, orange juice), while more alkaline substances taste bitter.

So what is the big deal about pH? Our body has but a narrow pH range

Figure 1.9 The pH of common substances, including our blood which has a pH of about 7.4.

4 Tomato juice (4.2)

10 Milk of magnesia (10.5)

11 Household ammonia (11.7)

13 Lye, caustic soda (13.0)

at which it can function appropriately. As noted on the scale in Figure 1.9, the pH of our blood is about 7.4. This means that the pH of our body is slightly basic. If the pH falls below or above 7.4 these conditions are referred to as acidosis and alkalosis, respectively. Nearly all chemical reactions in our body are controlled by enzymes, most of which function in our best interest at a pH around 7.4. Thus, when our pH falls or climbs, the efficiency of many enzymes is significantly affected. Some enzymes will work harder and others will work less hard, thus impacting key chemical reactions in our body. This can compromise normal function and possibly our vitality.

Inherent to our body are systems that help us maintain the pH of our body fluid (for example, blood) around 7.4. These systems are called buffering systems and they act either to soak up excessive hydrogen ions or to release them when our body pH begins to change. Thus pH can be maintained at the 7.4 ideal despite changing internal factors.

0 0

Post a comment