MDS on newer odges

How does this system work? i have read what i can find on the net...i know it pushes oil into a selinoid and disconects the lifters and shuts off the fuel and spark on 4 of the cylinders, but everything i have read says that when the lifters disconect that the valves close and remain closed until it switches back to 8 cylinders. this does not make sense to me, if u close both the exhaust and intake valves where does the compressed air inside the cylinder go. i have ran this question past a few of my motor head friends and it doesnt make sense to any of us.

I would be interested in learning more about it myself.
But my understanding is that it collapses the intake lifters on the four cyls, simple as that.

So if those four intake lifters don't open the valves, you have eliminated those from consuming the fuel.
Exhaust valves keep working.

Could be wrong, but that is how I understand it.