In the classic 1975 British comedy film "Monty Python and the Holy Grail," King Arthur battles a mysterious Black Knight who refuses to let him pass. Arthur handily vanquishes his foe by cutting off his limbs one by one, all while the knight, reluctant to admit defeat, insists the damage is "only a flesh wound."
Dark humor aside, it raises the question of just how much of your body you could lose and still survive. Of the roughly 80 organs in the human body, only five are defined as vital organs that are crucial for sustaining life: the brain, which orchestrates bodily functions; the lungs and heart, which take in and distribute the oxygen cells need throughout the body; the liver, which has important roles in digestion and blood detoxification; and the kidneys, which filter waste and excess fluid from the body.
Other important structures that are not traditionally considered vital organs include the intestines, which absorb nutrients from food; the pancreas, which makes essential hormones like insulin; and the skin, which guards against infection, according to Dr. Jessica Weaver, a trauma surgeon at UC San Diego Health.
Scientists debate whether some features, such as wisdom teeth and the tailbone, serve any purpose at all. Other body parts, like the eyes and the tongue, have major impacts on a person's quality of life, but they are not strictly necessary for survival.
Limbs may be handy (pun intended!), but people can survive without arms and legs if they need to be amputated. "In general, we will try harder to save an arm than a leg, because the functional outcome with a prosthetic for a leg is pretty good, especially if it's below the knee, whereas our hands are so important to what we do," Weaver told Live Science.
This means the Black Knight could have likely survived his ordeal if he had made it to a modern hospital, though Weaver said heavy blood loss would have likely stopped him from mustering his iconic taunt.
Stopping that blood loss before it turns deadly is the most pressing need in treating trauma patients. This threshold varies, but losing more than 3 of the roughly 5 liters of blood in an adult body is "pretty hard to come back from," she said.
Still, everybody's different. "I've definitely seen people survive things that I was sure they would die from, which is why I keep showing up to work," she added.
Can you survive without parts of your vital organs?
It is possible to survive without portions of the core vital organs. A person can live without much of the liver and a big chunk of their brain, as long as the brain stem remains intact to regulate involuntary functions, like breathing. Humans need only one kidney, and they sometimes donate one to a person in need. While an injury that damages all of these organs at once would be difficult to survive, Weaver said a patient could hypothetically live if the tissue were removed more gradually.
Vital organs can also be replaced, either through a transplant or with life-support organ-sustaining technologies, such as kidney dialysis and extracorporeal membrane oxygenation (ECMO), which performs the functions of the heart and lungs. The only two vital organs that cannot be replaced by a machine are the liver and the brain, Weaver said, though a liver transplant is possible.
"We are increasingly able to replace organ function mechanically or chemically," said Jason Wasserman, a professor of foundational medical studies at the Oakland University William Beaumont School of Medicine.
These medical advances complicate what it means to survive the loss of a given organ. Wasserman noted that while some organ-sustaining technologies like ventilators and dialysis can be used long-term, others like ECMO are a "bridge to treatment," such as an eventual transplant, not a "bridge to nowhere" used indefinitely. The decision to start or continue one of these interventions depends on its medical appropriateness for a patient's situation as well as the patient's personal values, he said.
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