Asked by: Neil Gibson, HerefordIn the 18th century, death certificates signed by the clergy listed as many as 41 different causes of death, including 'suffocated by wet nurse or mother'. However if you ignore the circumstances leading up to the death and simply consider the proximal mechanism itself, there are basically four different ways to cause total and irreversible loss of brain stem function: oxygen starvation, high temperature, chemical toxin and physical damage. So if you bleed to death, the thing that actually kills you is the fact that your brain is starved of oxygen. If you die of meningitis, it's a combination of the physical damage to the neurons by the swelling of the brain, plus the direct toxic effect of bacterial compounds. If you are hit by a car, you might die from the physical damage to your brain, oxygen starvation as a result of bleeding, or even the toxicity of a subsequent bacterial infection.