 The autonomic nervous system is divided into the sympathetic and the parasympathetic nervous system. Many times students have a little bit of difficulty relating medications to the different parts of the autonomic nervous system. So here's some tidbits. The sympathetic nervous system is the flight and flight response. So think about adrenal release, adrenal glands, adrenaline, sympathetic phytoflight. And that increases the blood pressure and the heart rate because when we want to run away, when we want to fight or flight, that needs to happen to supply our skeletal muscles with the blood flow that they need so we can participate in the fight or flight response. And then there are medications that actually mimic this adrenal response. And they are called sympathomimetics, so they mimic the sympathetic nervous system response. And the other term that we sometimes hear here is adrenergic agonists. So they agonize, they make the adrenergic response higher or heightened. And so medications that do that are usually anything that refers to the fight or flight response in an artificial form. And we can administer epinephrine as well as no epinephrine to the patient to have the sympathetic response. Now on the parasympathetic side, that is the rest and digest response. And that slows everything down. It slows the heart rate, it slows the blood pressure, so the blood flow can go to the digestive system to take care of the digestion of the food and let us rest. Now there are medications that are parasympathomimetics, although they are very rarely used. But the other word used for parasympathetic is cholinergic. And so medications that can be used to halt the parasympathetic response are called anticholinergics. So sympathetic, adrenergic, parasympathetic, cholinergic. Keep that in mind when you study your medications that affect the autonomic nervous system so that you can relate the signs and symptoms that these medications will cause.