When a person ingests caffeine, whether in the form of a cup of coffee or tea, a caffeinated soda, or even a piece of dark chocolate, the drug begins to take effect almost immediately. first, caffeine enters the bloodstream through the membranes of the stomach and small intestine. it is then metabolized by the liver, which breaks it down into other chemicals. within fifteen minutes of consumption, most people begin to feel the effects of caffeine, which can include increased heart rate and feelings of alertness or well-being. within six hours of consumption, about half of the original dose of the drug will have been eliminated from the body. this is why some people drink a second cup of coffee in the afternoon. what type of text structure is it?