An alkaloid is a group of bases that contain nitrogen that occur naturally. They are very important and significant in terms of the effects that they can have on human physiology and animal physiology. Some common names that a lot of people know but do not realize are alkaloids are morphine, ephedrine, and nicotine. Usually alkaloids are found in naturally occurring plants and they taste very bitter. Plants that grow alkaloids could be possibly poisonous, while some are completely harmless. Some more common names that are alkaloids are caffeine, guinine, and atropine. Caffeine is very well known and is one of the most used psychoactive substances in the United States. Thus, alkaloids play a significant part in human physiology and its effects on the body.