Now that the cannabis has been consumed, what happens to it?
When things are taken into our body there is a metabolic process which takes place; the way in which our body breaks down the chemicals taken in, and takes what it wants to use and disposes of the parts which are waste. This happens to any chemical that we take in, be it through absorption through the skin, inhalation, eating, or injection. Of course, depending on how we take in the chemical there are some differences in the metabolic path. The metabolic process changes the chemicals somewhat and these new versions are called metabolites; the changes sometimes make the chemicals less active and sometimes make them more active in an attempt to remove them from your body.
Ball-and-stick model of the 11-hydroxy-tetrahydrocannabinol
When testing is done for drugs within the body it is more often the metabolites (or one specific metabolite) of the drug that are being tested for, rather then the parent drug itself, though it does depend on the drug being tested. When cannabis is taken into the body it is the liver that is creating the metabolites. When the drug enters through the lungs the delta-9-THC travels into the blood stream and is pumped throughout the body by the heart to make its way to the liver for processing. Enzymes in the liver turn the original delta-9-THC (psychoactive) from the cannabis plant into the metabolite 11-OH-THC (psychoactive) which is then further metabolized into 11-COOH-THC (non-psychoactive). When cannabis is ingested the delta-9-THC enters the bloodstream through the walls of the stomach and intestines, where it first travels to the liver where most of it is eliminated or metabolized before it ever has a chance to activate receptors in the brain. This is why there is great variation in how edibles affect the body as well as when they show up in a drug test.