Natural Defenses: The Immune System and Its Functions

Abstract

            The world around us is teeming with microscopic organisms called microbes, some beneficial, some harmless, and some harmful. When it comes into contact with the harmful types of microbe, the body relies on its natural defenses, finely tuned of thousands of years of evolution to detect and neutralize harmful invaders while leaving the surrounding tissues for the most part undamaged. It takes many different types of cells and cellular secretions to do this, and without these cells and the biochemical processes they perform, no complex life could survive here on Earth.