Human digestive system

Your body has a very busy way of using food to stay healthy.

This is called the digestive system. It is made of a long tube called the gastrointestinal tract. This tube starts at your mouth and ends at your anus. The tract is very large and covers a long distance. Many other parts help out too. These are called accessory organs. They include your tongue, salivary glands, pancreas, liver, and gallbladder.

Digestion is the way your body breaks food into tiny pieces. Once food is small enough, your body can absorb it. This gives your body the energy it needs to work.

Digestion happens in three main stages. First is the cephalic phase. This starts even before you take a bite. When you see or smell food, your body reacts. Your gastric glands start to make secretions. Next, the food enters your mouth for mechanical breakdown. This means your teeth and muscles chew the food. Your tongue helps move the food around.

Saliva also starts a chemical breakdown. It contains enzymes like amylase and lingual lipase. These tools begin to break down starch and fats. Chewing mixes food with saliva to make a soft ball called a bolus. You then swallow the bolus down the esophagus.

The second stage is the gastric phase. This takes place inside your stomach. Your stomach has millions of tiny gastric glands in its lining. These glands make gastric juice. This juice contains gastric acid to help break food down further. The food mixes with this juice until it becomes a liquid called chyme.

The food then moves into the duodenum. The duodenum is the very first part of the small intestine. To move the food along, your body uses peristalsis. Peristalsis is a way of using rhythmic muscle contractions. These contractions push food through the esophagus and the rest of the tract.

The third stage is the intestinal phase. Most of the digestion happens in the small intestine. This is the longest part of the gastrointestinal tract.

Here, the food mixes with enzymes from the pancreas. The partially digested food eventually becomes a liquid called chyle. This chyle is absorbed into your lymphatic system. After the small intestine, the food enters the large intestine. The colon is the main part of the large intestine. It is the largest part of the whole tract. The large intestine absorbs water and some minerals back into your blood.

Your digestive system works much like a long assembly line.

In a factory, machines break things down to make something new. Your body does something similar with your meals. It uses different tools at every stop along the path. Your teeth act like grinders to crush the food. Your enzymes act like tiny scissors to cut the food apart. Even your sense of taste is part of this system. Taste buds on your tongue help you sense salt, sour, bitter, sweet, and umami. This helps your body decide if food is safe to eat. Finally, any waste left over is stored in the rectum. It then leaves your body through the anus.