Five vital organs keep you alive—but how much can you lose?

The human body contains around 80 organs, yet only five are essential for survival. These vital organs—the brain, lungs, heart, liver, and kidneys—keep a person alive. But even parts of these can sometimes be lost or replaced without fatal consequences.

A person can survive the removal of sections from key organs, such as the liver or parts of the brain, as long as critical functions remain. The liver, for example, can regenerate after partial loss, while certain brain injuries may leave a person alive but with lasting effects.

Transplants and life-support machines also offer alternatives when organs fail. Kidneys can be replaced through dialysis, while devices like ECMO temporarily take over heart and lung functions. However, not all solutions are permanent—some, like ECMO, are only short-term fixes until a transplant becomes available.

Blood loss poses another serious risk. An adult losing 3-5 litres of blood may not survive, depending on their health and how quickly the bleeding occurs. In contrast, losing limbs, though life-altering, does not directly threaten survival.

Modern medicine allows people to live without full use of some vital organs, either through transplants or temporary support systems. Yet long-term survival often depends on the organ involved and the availability of medical interventions. While some technologies provide only brief relief, others—like dialysis—can sustain life for years.