If foreign substances pass the body's first line of defense and into the bloodstream what happens

The good cells attack it and try to kill it if its a bad substance

Dropping a dry bar of soap on the ground won’t clean it, by it will pick up germs from the ground so the soap would be dirty

Well if you pick a machine to work on and that's gonna be your exercise if you don't stick to that machine your muscle strength your muscle mass rather will change because you haven't been doing it you change something in your exercise routine which changes your body's form of dealing with things for example you might become weaker or stronger depending on what kind of exercises you do in whether or not the machine you picked actually your muscles grow.