What Are the Different Sections Of the Alimentary System and How Do They Function?
The alimentary system plays a key role in the process of digestion, absorption, excretion and provision of energy/nourishment. The two forms of digestion are extracellular and intracellular. Extracellular deals with digestion which occurs outside of the cell in the true alimentary system. Whereas, intracellular digestion breaks down nutrients within the cells and is mainly associated with unicellular organisms. Extracellular digestion can be categorized as either being a batch reactor (coelenterates), continuous-flow reactor (all phyla higher than flatworms),or a plug-flow reactor (most mammals). The batch reactor system brings food in batches. The food is then digested and excreted before another batch of food is taken in. The continuous-flow reactor continually carries in and mixes food and excretes food products. The last form of extracellular digestion is the plug-flow reactor. In this type, food is taken in and digested while it winds through long tubes in the digestive system. Th
