our bodies are like complex factories that function day and night without pause in a never-ending cycle of renewal and decay. New cells and tissues are created, old worn-out matter is broken down, recycled or excreted, and our organs continue to function, day in and day out, without requiring any direction from us. We provide the building blocks and the source of energy for these processes through the food we eat, the liquids we drink, and the air we breathe. Everything runs smoothly in its appointed manner until a glitch in the system creates havoc, and we then have to deal with the consequences of this malfunction.