The Song of the Cell: An Exploration of Medicine and the New Human

by Siddhartha Mukherjee

But death isn’t a flying apart of organs. It is the withering grind of injury set against the ecstasy of healing. Tenderness, as Ryan puts it, combatting rot. The central corporals in this pitched battle are cells—cells dying in tissues and organs, and cells regenerating tissues and organs. Return, for a moment, to the notion of homeostasis—the maintenance of a constancy in the internal milieu. We first evoked this idea to understand how the cell maintains its internal fixity. We then used it to understand how a healthy body adjusts to metabolic and environmental changes—salt load, waste disposal, sugar metabolism. We apply it, now, to the maintenance of balance between injury and repair. Death—the most absolute of absolutes—is, in fact, a relative balance between forces of decay and rejuvenation. If you tip the balance in one direction—when the rate of injury overwhelms the rate of recovery or regeneration, you fall off the edge. The osprey, buffeted by the changing winds, cannot remain suspended in midair. I