Yes, it's difficult to remain calm when your teen seems to be deliberately acting thick-headed, but you should realize that when you model respectful, pleasant behavior you will keep your relationship with your teen healthy; teens who are on good terms with their parents do take their parents' feelings and opinions into account. The time that you spend working on a good relationship with your teenagers, whether taking them out for one-on-one time or giving them your undivided attention when they want to talk, will save you much time arguing in the future. In addition, your remaining calm will keep the argument from escalating and will set a positive example of how people are able to peacefully resolve conflicts, a skill your teens can use for the rest of their life.
When your teens argue with you, first take a minute to examine whether they have a point or if the whole issue isn't worth the fight. If you decide that you have to take a stand on this matter, let your teen feel that you're listening ("I hear you." "Anything more you want to add?") and try not to turn the argument into a power struggle. You can stay firm but empathetic, and tell yourself, "I'm the adult here; I can demonstrate mature communication techniques." Don't call your teen names (selfish, lazy, stupid), and speak in a calm, quiet tone of voice.
If you sense that the timing isn't right or that tempers are rising, you can tell your teen that you'll discuss it later. You can call a friend, go out for a walk while you calm down and think over your options, or count to 10 (or to 100). If your teenager becomes violent, call the police (that's what they're there for); usually one call to the law will teach your teen that violence is not tolerated in your house.