What is digestion?
Enter the intestine

Most of the absorption of nutrients takes
place in the small intestine.

Now that our bite of cheeseburger has been turned into chyme and is now on its way to the small intestine, let us take a look at how our cheeseburger has changed from its former state:
• the bread, which contains complex carbohydrates, was changed by the amylase into simpler sugars;
• the burger patty and cheese, which contains complex proteins, was changed by the pepsin into simpler proteins; and
• the vegetables are already digested, but most of the fiber is still intact.

In the small intestine, the chyme is further processed by more muscular contractions and enzymes that would allow it to finally be absorbed.

Simple explanation:
After passing through the various organs of the digestive system, the food you have eaten enters the small intestine. Enzymes are added into the chyme in order to counter the acidity of the gastric juices from the stomach. These enzymes, along with the peristaltic movements of the small intestine, would also convert the remaining complex particles and allow for the absorption of the nutrients.

Except for the first portion of the small intestine known as the bulb, the whole inside surface area is covered with folds that absorb the various nutrients in the food. This absorption of nutrients is called osmosis, where the nutrients pass through the membranes of the cell and enter the bloodstream in order to transport the nutrients to various cells all over the body.

Advanced explanation:
The small intestine is made up of three regions, namely the duodenum, the jejunum, and the ileum. The first region is connected to the liver, gallbladder and pancreas through ducts, which provide juices that neutralize acids coming from the stomach and help digest food even more, such as the pancreatic juice which digest proteins and fats and bile from the liver which helps absorb these nutrients into the bloodstream.

The second region contains an extensive supply of blood in order to facilitate the ease of absorption of nutrients. It is here that the various complex components of food, now turned into monosaccharides from carbohydrates, into peptides and amino acids from proteins, and into monoglyceride and free fatty acids from neutral fat (lipids), are absorbed by the bloodstream. However, this absorption through osmosis would not be possible without the help of transporters such as sodium. Sodium carries the various nutrients that need to be absorbed into the cell, since nutrients like monosaccharides and amino acids cannot simply pass through the cell membranes through osmosis.

The third region of the small intestine is responsible for further absorption of nutrients such as vitamin B12 and the reabsorption of bile salts extracted by the liver from the bloodstream. Bile salts are stored in the gallbladder, and it allows for the absorption of fat.

Food may stay up to four hours in the small intestine before it is pushed toward the large intestine.

This last region is also connected to the large intestine, where undigested food particles, now known as ingesta, from the small intestine will get the last chance to be absorbed by the body. Without further ado, we move on to the large intestine, the last chance.

Or go back to the previous page.


Most of the absorption of nutrients takes place in the small intestine.		Now that our bite of cheeseburger has been turned into chyme and is now on its way to the small intestine, let us take a look at how our cheeseburger has changed from its former state: • the bread, which contains complex carbohydrates, was changed by the amylase into simpler sugars; • the burger patty and cheese, which contains complex proteins, was changed by the pepsin into simpler proteins; and • the vegetables are already digested, but most of the fiber is still intact. In the small intestine, the chyme is further processed by more muscular contractions and enzymes that would allow it to finally be absorbed. Simple explanation: After passing through the various organs of the digestive system, the food you have eaten enters the small intestine. Enzymes are added into the chyme in order to counter the acidity of the gastric juices from the stomach. These enzymes, along with the peristaltic movements of the small intestine, would also convert the remaining complex particles and allow for the absorption of the nutrients. Except for the first portion of the small intestine known as the bulb, the whole inside surface area is covered with folds that absorb the various nutrients in the food. This absorption of nutrients is called osmosis, where the nutrients pass through the membranes of the cell and enter the bloodstream in order to transport the nutrients to various cells all over the body. Advanced explanation: The small intestine is made up of three regions, namely the duodenum, the jejunum, and the ileum. The first region is connected to the liver, gallbladder and pancreas through ducts, which provide juices that neutralize acids coming from the stomach and help digest food even more, such as the pancreatic juice which digest proteins and fats and bile from the liver which helps absorb these nutrients into the bloodstream. The second region contains an extensive supply of blood in order to facilitate the ease of absorption of nutrients. It is here that the various complex components of food, now turned into monosaccharides from carbohydrates, into peptides and amino acids from proteins, and into monoglyceride and free fatty acids from neutral fat (lipids), are absorbed by the bloodstream. However, this absorption through osmosis would not be possible without the help of transporters such as sodium. Sodium carries the various nutrients that need to be absorbed into the cell, since nutrients like monosaccharides and amino acids cannot simply pass through the cell membranes through osmosis. The third region of the small intestine is responsible for further absorption of nutrients such as vitamin B12 and the reabsorption of bile salts extracted by the liver from the bloodstream. Bile salts are stored in the gallbladder, and it allows for the absorption of fat. Food may stay up to four hours in the small intestine before it is pushed toward the large intestine. This last region is also connected to the large intestine, where undigested food particles, now known as ingesta, from the small intestine will get the last chance to be absorbed by the body. Without further ado, we move on to the large intestine, the last chance. Or go back to the previous page.