What is digestion

Written By The HealthMeth Team - Updated On Saturday, March 13, 2021 6:00 PM

Definition of digestion

The digestion process is defined as the process of breaking down food and drink, which are the source of energy for the body, into smaller molecules in the form of carbohydrates, proteins, fats and vitamins, so that the body is able to use them to provide energy for the cells to do their work, and the digestive system in the body completes this process in an integrated manner among its parts . [1]

Parts of the digestive system

The digestive system consists of several parts that work in an integrated manner to complete the digestive process, namely: [2]

  • Mouth: The mouth breaks down and chews food, and flips it with saliva to digest it into smaller parts that the body can absorb.
  • Esophagus: The esophagus receives food from the mouth and directs it towards the stomach.
  • Stomach: The stomach contains food and mixes it with digestive enzymes and then directs it to the small intestine.
  • Small intestine: The small intestine increases the digestion of food by using the enzymes produced by the pancreas, and the bile juice produced by the liver. After converting food from the solid form to the liquid form, it is directed towards the large intestine or colon.
  • Pancreas: The pancreas secretes digestive enzymes into the duodenum, in addition to producing insulin and releasing it into the blood to stimulate the metabolism process.
  • Liver: The liver absorbs nutrients from the small intestine, and it helps to secrete bile to digest fats, and it also makes chemicals that the body needs through what it absorbs from the intestine, in addition to ridding the body of toxins.
  • Gallbladder: The gallbladder stores bile and releases it to the duodenum when it needs help digesting and absorbing fats.
  • Large intestine: The large intestine or colon processes liquid food residues coming from the small intestine, absorbs water from them and converts them to a solid form with the aim of eliminating them in the form of feces.
  • Rectum: The rectum connects the colon and the anus, and works to receive stool from the colon, then sends signals to the brain, and maintains stool until it is eliminated.
  • Anus: The anal canal is made up of muscles in the lower pelvis and two sphincter muscles, internal and external, which help control the process of elimination.

Control the digestive process

The digestion process in the body is controlled and guided by the following factors: [3]

  • Hormones : Hormones are secreted by cells lining the stomach, small intestine and pancreas, which in turn stimulate the digestive system to produce digestive juices, and send signals to the brain to alert it to the body's state of hunger or satiety, and thus regulate the digestive process.
  • Nerves : The nerves regulate the work of the digestive system in two ways, in the first way, the integration between the central nervous system and the digestive system is done by sending signals from the brain to the digestive system to prepare for the process of eating when smelling or seeing food, then the secretion of saliva in the mouth is stimulated as a preparatory step. In the second way, the nerves in the enteric nervous system release various substances that speed up or slow down the movement of food and produce digestive juices, followed by sending signals that control the intestinal muscles and make them contract and relax in order to push food through them.


  1. Nadine James, "What is Digestion? - Definition & Process" , www.study.com , Retrieved 17-1-2018. Edited.
  2. "The Structure and Function of the Digestive System" , www.clevelandclinic.org , Retrieved 17-1-2018. Edited.
  3. "Your Digestive System & How it Works" , www.nih.gov , Retrieved 17-1-2018. Edited.