[the students listen to their biology teacher talk about the human digestive system]Biology Teacher: So, to review... the solid waste, those nutrients not absorbed by the lining of the stomach, the large intestine, the small intestine, and the alimentary canal, are passed down through the colon.[Ron makes a farting sound as the rest of the students chuckle]Biology Teacher: Liquid nutrients are then carried through an elaborate system of filtering, aided by the pancreas, liver, and gall bladder or collected in the gall bladder to be expelled at a later time.[another student makes a gagging sound as the students laugh some more]Biology Teacher: And, this entire process has kept moving through the circulatory system... the center of which is...Biology Teacher: [the biology teacher drops a human heart on the desk] The heart.Ron Grady: [Ron yells out] Yeah!