<Tr> <Th_colspan="2"> Identifiers </Th> </Tr> <Tr> <Th> Latin </Th> <Td> systema digestorium </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> Digestion is the breakdown of large insoluble food molecules into small water - soluble food molecules so that they can be absorbed into the watery blood plasma . In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream . Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion . The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes . In chemical digestion, enzymes break down food into the small molecules the body can use . </P>

When does the intestinal phase of digestion begin