The digestive system can be seen as the body’s own food-processing factory. It provides two critical functions: digestion and absorption of nutrients. The body is unable to absorb or use large food molecules and therefore has to break them down into smaller and more manageable units before they can be assimilated. This is the job of the digestive system and it fulfils this role through the combined efforts of chemical and mechanical digestion.
Many of the components of the digestive system secrete special substances called enzymes. Enzymes are chemical catalysts and speed up the digestive process by breaking down the large, unabsorbable macronutrient molecules into smaller, absorbable ones. The enzymes themselves are not changed in these reactions and just like a lock and key, each enzyme will only work on specific nutrients.
Digestion and absorption of all nutrients takes place within the gastrointestinal tract (GI tract). The GI tract is a hollow tube that runs from the mouth to the anus. The organs that make up the GI tract are the mouth, pharynx, oesophagus, stomach, small/large intestines and the anus. Each of these components fulfils a precise function.