The requirement for the ingestion of food, as a source of energy and to supply nutrients and energy for cell reproduction and growth was applied at the start the class. A discussion of the need for digestion to change the complex organic nutrients ingested into simpler organic molecules which can be absorbed and transported to the cells was undertaken. The division of the digestive system into two major sections, the alimentary canal and the accessory organs was defined on the board, with the corresponding organs and glands for each part listed. The physiology of each will be discussed in the next few lessons. A diagram of the system, labeled, was used to reinforce the system.