system
Given the following post, respond as if you're commenting on Reddit:
human
What actually kills you when you are dehydrated?

What goes on in your body that causes you to die from dehydration?
gpt
The two most significant issues with severe dehydration are the loss of perfusion volume as well as the electrolyte abnormalities that develop.  If someone is hypovolemic enough, they will not be able to maintain an adequate blood pressure to supply oxygen to their organs, which results in multi-organ failure (in particular, the heart, brain, kidneys, and liver are particularly vulnerable).  In addition, changes in electrolyte concentrations in the blood (most typically sodium or potassium) can result in comas or seizures as well as cardiac arrhythmias.