Final answer:
Free radicals can enter our body through environmental exposure, such as pollution and radiation, and lifestyle choices like smoking and consuming alcohol. Antioxidants in our body neutralize these radicals to prevent cellular damage.
Step-by-step explanation:
Free radicals can enter our body through various ways, but two common ways are through environmental factors and lifestyle choices. Firstly, environmental exposure to pollutants, radiation from the cosmos, and ultraviolet rays can lead to the formation of free radicals in our bodies. Sources of such exposure include air and water pollution, as well as solar and cosmic radiation. Secondly, lifestyle choices such as smoking tobacco, consuming alcohol, eating foods high in trans fats, and exposure to certain chemicals are significant contributors to the production of free radicals within our bodies.
To combat the detrimental effects of free radicals, our bodies utilize antioxidants like vitamins C and E and provitamins like ß-carotene. These substances can neutralize free radicals by donating atoms and breaking the propagation chain reaction, thus preventing cellular damage and the development of certain diseases. It's important to note that while free radicals play a role in harmful processes like aging and disease, they are also part of necessary signaling processes and immune responses.