Digestive System

The digestive system is a group of connected organs that work together to break down the food we eat into smaller parts. These smaller parts can then be absorbed by the body and used for energy, growth, and repair. The system starts at the mouth and ends at the anus. Along the way, several organs help with digestion, either by moving the food or by producing substances that help break it down.

1. Mouth

Digestion begins in the mouth. When we eat, the food is placed in the mouth where it is broken into smaller pieces.

Inside the mouth, there are teeth, saliva, and the tongue that work together. The teeth chew the food, breaking it into smaller parts. The tongue helps move the food around and mixes it with saliva, which is a watery fluid made by the salivary glands. Saliva contains enzymes that start breaking down carbohydrates.

Once the food is soft and mixed well, the tongue pushes it to the back of the mouth where it is swallowed.

2. Teeth

Teeth are important for the first step in digestion. Their main job is to cut, tear, and grind the food into smaller pieces so it can be swallowed easily and digested properly.

There are four main types of teeth:

• Incisors – These are the front teeth used for cutting food.

• Canines – These are pointed teeth used for tearing food.

• Premolars – These are flat teeth used for crushing food.

• Molars – These are larger teeth at the back used for grinding food.

3. Esophagus

After swallowing, the food goes down a tube called the esophagus. This is a long, muscular tube that connects the mouth to the stomach. Muscles in the walls of the esophagus gently push the food down in a wave-like motion. This movement is called peristalsis. It takes only a few seconds for food to move from the mouth to the stomach.

4. Stomach

The stomach is a hollow, muscular organ that holds the food after it enters from the esophagus. Its main job is to break the food down into a liquid or paste-like form.

The stomach does this in two ways:

• It squeezes and churns the food using its muscles.

• It mixes the food with digestive juices, including acid and enzymes, which help break down proteins.

The food stays in the stomach for a few hours. By the time it leaves, it has become a thick liquid called chyme.

5. Small Intestine

The small intestine is a long, narrow tube where most digestion and absorption happens. It is about 6 meters long and is divided into three parts:

• Duodenum – The first part, where bile and enzymes mix with the chyme.

• Jejunum – The middle part, where digestion continues and nutrients begin to be absorbed.

• Ileum – The last part, where most of the remaining nutrients are absorbed into the bloodstream.

The walls of the small intestine have tiny finger-like shapes called villi, which increase the surface area so more nutrients can be absorbed.

6. Liver

The liver is a large organ located on the right side of the body, above the stomach. It has many important functions, but in digestion, its main role is to produce bile.

Bile is a yellow-green fluid that helps break down fats into smaller pieces so they can be digested more easily. The liver also helps store nutrients, remove harmful substances from the blood, and manage the balance of chemicals in the body.

7. Gallbladder

The gallbladder is a small organ located just under the liver. It stores the bile made by the liver. When you eat fatty food, the gallbladder releases bile into the small intestine. This helps in the digestion of fats. If the gallbladder doesn't work properly, fat digestion can become difficult.

8. Pancreas

The pancreas is an organ located behind the stomach. It has two main functions:

• It produces digestive enzymes that are sent into the small intestine. These enzymes help break down carbohydrates, proteins, and fats.

• It also produces hormones, like insulin, which help control the amount of sugar in the blood.

So, the pancreas works in both digestion and in controlling blood sugar levels.

9. Large Intestine

After nutrients are absorbed in the small intestine, the leftover material passes into the large intestine. This organ is wider but shorter than the small intestine.

Its main jobs are:

• To absorb water and some minerals from the waste.

• To turn the remaining material into solid waste, called feces.

The large intestine includes the colon, rectum, and ends at the anus, where the waste leaves the body.

10 Rectum

The rectum is the last part of the large intestine. It is a short, straight section that connects the colon (the main part of the large intestine) to the anus.

Function of the rectum:

• The rectum stores solid waste (called feces) that has been left over after water and nutrients have been absorbed in the large intestine.

• When the rectum becomes full, it sends signals to the brain telling you that you need to go to the bathroom.

• It acts as a temporary holding place for waste until it is ready to be expelled from the body.

11 Anus

The anus is the opening at the end of the digestive tract through which waste leaves the body.

Function of the anus:

• It controls the release of feces from the body.

• It has muscles called sphincters that open and close to keep waste inside until you are ready to go to the bathroom.

• When you decide to pass stool, these muscles relax and allow the feces to leave the body.

How they work together

Waste moves from the colon into the rectum where it is stored. When the rectum fills up, you feel the urge to have a bowel movement. Then, the muscles around the anus relax so that the waste can leave the body.