Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Antioxidants in the Human Body

About 5 percent of the oxygen humans breathe is converted into free radicals. The presence of free radicals in the body is not always detrimental. Free radicals produced in normal cellular metabolism are vital to certain body functions, such as fighting disease or injury. When tissue is diseased or damaged, the body’s immune system sends disease fighting cells to the site, where they produce free radicals in an effort to destroy foreign invaders.

But as the body ages or is subjected to environmental pollutants, such as cigarette smoke, overexposure to sunlight, or smog, the body becomes overwhelmed by free radicals. An excessive number of free radicals causes damage by taking electrons from key cellular components of the body, such as protein, lipids, and deoxyribonucleic acid (DNA), the molecule that carries genetic information in every living cell. These reactions make cells more vulnerable to cancer-causing chemicals, called carcinogens. Free radicals may lead to heart disease by oxidizing low-density lipoprotein (LDL) cholesterol, the so-called bad cholesterol. Researchers now believe that only the oxidized form of LDL cholesterol leads to hardening of the arteries, a condition that can ultimately lead to heart disease. Free radicals have also been implicated in cataract, a clouding of the lens of the eye that can lead to blindness.