Digestion is defined as the process in the gastrointestinal tract by which food is broken up physically through the action of the teeth and chemically, via enzymes and finally converted into a substance suitable for absorption and assimilation into the body.
The digestive system, is comprised of the gastrointestinal tract (GIT) and supporting organs.
The GIT consists of the following sections:
– Mouth
– Oesophagus
– Stomach
– Pyloric valve
– Duodenum (small intestine)
– Jejunum (small intestine)
– Ileum (small intestine)
– Ileocaecal valve
– Ascending, transverse, descending colon (large intestine)
– Rectum
– Anal canal
Food is then digested via mechanical digestion where foods enters the GIT in the mouth, digestion is started by the teeth and tongue and then pushed down entire length of GIT where food is reduced to small particles and mixed well with digestive juices. This allows food to have maximum exposure to digestive enzymes and to be given maximum exposure to absorptive surfaces of GIT
The time that it takes for meals to be digested:
LIQUIDS: 15 – 30 minutes
FATS: 20 – 36 hours
MIXED MEALS: ± 48 hours
Final product of carbohydrate digestion: glucose
Final product of protein digestion: amino acid
Final product of lipid digestion: fatty acids