Role of Organs in Digestion and Absorption

The digestive system involves several principal organs that work together to break down and absorb nutrients from food. These include the mouth, stomach, liver, gallbladder, pancreas, and intestines.
Digestion begins in the mouth, where food is broken down into smaller pieces by the teeth, while salivary glands secrete saliva to further soften and break down the food.
The resultant mix, called a bolus, is swallowed and moves down the oesophagus towards the stomach via peristaltic action.
Upon reaching the stomach, the food is mixed with gastric juices, which contain enzymes including pepsin, that break proteins down.
The small intestine is where most of the digestion and nutrient absorption happens. It is lined with villi which increase the surface area, allowing nutrients to be absorbed more efficiently into the bloodstream.
The liver produces bile, which neutralises the acid from the stomach to create suitable conditions for enzymes in the small intestine. The gallbladder stores this bile until it is required for digestion.
The pancreas releases various enzymes (like amylase, lipase) that help break down carbohydrates, fats, and proteins in the small intestine.
In the large intestine (colon), water, salts and some vitamins are absorbed and the leftover undigested food is formed into faeces to be excreted via the rectum and anus.
Undigested materials, including fibre, are expelled from the body through the rectum in the process of egestion.

Remember, these organs must perform their unique roles for efficient digestion and absorption. Maintaining a healthy diet aids these organs in their functions, supporting overall health. Regular revision of these key points can be a great way to reinforce understanding of this essential biological process.