system
Given the following post, respond as if you're commenting on Reddit:
human
[The Matrix] Why do people in the Matrix that get injured show signs of damage in real life?

For example when Neo gets unplugged from the jump program and he finds blood on his mouth. How could the Matrix create such a strong suggestive placebo effect, that it could actually tear skin? Or an more confusing example, when Neo brings Trinity back to life by literally restarting her heart within the Matrix. How could that transfer into real life. If her brain was tricked into dying, and the monitor still reads that her brain is dead, how could she restart her heart independently, since nothing happened to her in the real world?
gpt
Many of the signs of injury are actually caused by your body. Inflammation is a major contributor to what we think of as "injury". Inflammation is your body's response to damage. It is telling you "this part hurts. Don't move it." Unfortunately, large amounts of inflammation can actually damage your body. 

When your brain believes that your body has been seriously damaged, it attempts normal damage response. It causes inflammation and blood coagulants to flow, various hormones are release, etc. This can cause physiological effects similar to real injury.