Good informative video, video explains its not just about the pain.
The liver is linked to the autonomic nervous system (which controls involuntary body functions), Liver shots cause blood vessels to dilate, normally these results in an increased heart rate to maintain blood pressure. However, the liver shot also causes a decrease in heart rate which in turn causes a drop in blood pressure. Since blood supply to the brain is an essential life function the brain forces the body into a horizontal position in a bid to survive.
The liver is linked to the autonomic nervous system (which controls involuntary body functions), Liver shots cause blood vessels to dilate, normally these results in an increased heart rate to maintain blood pressure. However, the liver shot also causes a decrease in heart rate which in turn causes a drop in blood pressure. Since blood supply to the brain is an essential life function the brain forces the body into a horizontal position in a bid to survive.