It's not much of a communication, it's more of a lack of that. Depending on what part fails, you'll have a different order of shutdown, but essentially death happens when your body can't get enough oxygen to keep its processes going. Either your brain stops functioning and thus the rest of your body doesn't get the automatic signals to breathe and move blood, or your heart is damaged and now your brain doesn't get oxygen and you pas out and die, or...you get the idea. Maybe you lost so much blood that it just can't ferry enough oxygen to your vitals, and they shut down.

Your microbiome (bacteria, fungi, etc in and on you) will begin to eat you. If you die in an open area, larger scavengers probably will come pick at you too. Your muscles will first lock up (rigor mortis) and then loosen over time. Your body will grow cold (algor mortis), and then your skin will discolor as blood pools in whatever the lowest parts of your body are for the position you're in (livor mortis). Your skin will desiccate and retract, giving the appearance that your nails and hair have grown. As your muscles relax, you'll release whatever was in your bladder and bowels at the time. Amusingly, if you have a penis, you'll probably get an erection for a while.