The vagus nerve was a nerve located in human and android bodies. However, its structure differed between the two, allowing androids to commit suicide by holding their breath.
Behind the scenes
The vagus nerve, also called pneumogastric nerve or cranial nerve X, is the tenth of twelve (excluding CN0) paired cranial nerves. Besides output to the various organs in the body, the vagus nerve conveys sensory information about the state of the body's organs to the central nervous system. 80-90% of the nerve fibers in the vagus nerve are sensory nerves communicating the state of the viscera to the brain. Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure, or both.
The difference in biology between humans and androids relating to the vagus nerve is only mentioned in Do Androids Dream of Electric Sheep? and its graphic novel adaptation.