The digestive system is the set of organs that help from the processing of food to excreting it from our body. It starts from the mouth and ends at the anus. The digestive system consists of the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.
When we feel hungry or smell certain foods, the salivary glands in our mouths produces saliva. This is the first process in digestion. When we put food, into our mouth, the saliva softens it and the teeth help to grind it. The tongue helps to mix the food and saliva. Here the food is broken down into smaller pieces.
Once we swallow the food, it is sent to the esophagus. A flap controls the movement of food to the esophagus so that we do not accidentally choke.
The muscular tube for the passage of food from the throat to the stomach is called the esophagus. It is also called the gullet. Muscles in the wall of the esophagus work together in a synchronized movement that consists of contractions and relaxations that help to push the food into the stomach. This movement is called peristalsis. The food reaches a valve called the sphincter. It is situated at the base of the esophagus, which opens and allows the foods to enter the stomach. The stomach helps to break down the food into a thick fluid called the chyme.
There are glands present in the lining of the stomach. When food enters the stomach, these glands produce gastric juice, which is made up of enzymes and acid, which help to churn the food to chime. With the aid of muscular movements in the stomach, this chyme is pushed through the pyloric valve into the small intestine.
The small intestine
The small intestine has three parts – the duodenum, jejunum and ileum.
The duodenum neutralizes the acid present in the food. The digestion of a major part of the fats, carbohydrates and protein take place here. The food mixes with digestive enzymes present here along with the mucous and bile. The middle part of the small intestine is called the jejunum, which is followed by the final part called the ileum. It is here where fingerlike bumps called ville absorbs the nutrients in the food. The rest of the digested food, which consists of water, electrolyte and fibers, is transferred to the large intestine.
Now we know that when food is in our small intestine, it mixes with various digestive juices. The liver, pancreas and gallbladder produce most of these juices.
The liver produces bile juice, which aids in breaking down fat. The liver performs very important functions like storing glycogen that converts to glucose when we need it and filtering chemicals in the food and processing them.
The pancreas produces digestive enzymes that are required to breakdown fat, proteins and carbohydrates and neutralizes the acid present in food. Insulin is produced in the pancreas.
Bile in concentrated form is stored in the gall bladder. When foods containing fat reach the small intestine, the bile is sent through the bile duct to break down the fat.
The large intestine is made up of the cecum, appendix, colon and rectum. When the remaining food passes through the large intestine, the water present is absorbed. The remaining digested food is converted into soft stool and goes out of the body by bowel movement through the rectum.