The digestive system includes the digestive tract and other organs which help the body in breaking down and absorbing food. It comprises a long, twisting tube which starts from the mouth and passes through the oesophagus, small intestine, large intestine and anus.
The digestive system helps in breaking down food into nutrients such as carbohydrates, fats and proteins. They get absorbed into the bloodstream. It is vital for attaining energy, and also for the growth and repair of the body. The unused materials get discarded as faeces.
Organs such as pancreas, liver and gallbladder are also part of the digestive system.
How does the digestive system function?
Each organ of the digestive system has an important role to play in digestion.
As we eat, our teeth help us in chewing food into very small pieces. The food is coated by saliva produced by glands in the cheeks and under the tongue. As a result, it becomes easier for us to chew and swallow food.
Saliva has enzymes which initiate the digestion of carbohydrates in food.
As we swallow the food, it gets carried from the mouth to the stomach via a muscular tube which is called the oesophagus. As the ring of muscle at the end of the oesophagus relaxes, the food enters into the stomach. The muscle contracts as well to stop stomach contents from escaping back to the oesophagus.
Gastric juice (hydrochloric acid and enzymes) is produced by the stomach wall which helps in the digestion of proteins. The stomach functions like a concrete mixer. Food particles and gastric juice mix with each other to form a thick, soupy liquid called chyme.
Proteins are broken down into amino acids and fat into fatty acids at the upper section of the small intestine with the help of bile from the gallbladder and enzymes in the digestive juices from the pancreas. Sugar, vitamins, minerals and other small particles are absorbed into the bloodstream via the wall of the small intestine.
The small intestine provides lots of area for absorption as it is about 5m long. It is called ‘small’ because it has a diameter of mere 3.5 cm. A major part of the chemical digestion of proteins, fats and carbohydrates is done in the small intestine.
Large intestine and Anus
Water, mineral salts and vitamins are absorbed by the lining of the large intestine. Mucus and bacteria get mixed with undigested fiber. This helps in keeping the large intestine healthy. The last part of the large intestine where the faeces are formed and stored is called the rectum. Faeces is passed out of the body through anus.
Conditions related to digestive system
Gastro-oesophageal reflux causes a burning sensation in the chest or throat. It happens when acidic stomach contents move from the stomach back up the oesophagus.
Inflammation or infection of abnormal pouches in the lower part of the large intestine causes diverticulitis. The patient will suffer from mild or severe pain on the lower left-hand side of the abdomen.
Helicobacter pylori causes stomach ulcers. It results in long-term, low-level inflammation of the stomach lining.
Itchy or painful lumps develop in and around the anus. The lumps will cause bleeding as they contain swollen blood vessels.
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Check your knowledge
Answer) The digestive system includes the digestive tract and other organs which help the body in breaking down and absorbing food.
Answer) Food particles and gastric juice mix with each other to form a thick, soupy liquid called chyme.
Answer) Gastro-oesophageal reflux, Diverticulitis, and Haemorrhoids.