Nutrient Absorption in the Large Intestine

Chyme is formed in the stomach as a result of the digestion of food, which occurs after it has been digested and swallowed and before it has passed through the oesophagus into the stomach. 

Chyme travels from the stomach to the duodenum, where it is digested. 

There, it combines with bile and pancreatic fluids, which aid in the breakdown of nutrients even more.

The villi, which are finger-like projections that line the inside wall of the small intestine, are responsible for absorbing the majority of the nutrients. 

The leftover chyme and water are transported to the large intestine, where they complete the absorption process and eliminate waste products.

The large intestine is responsible for completing absorption and compacting waste.

It travels from the small intestine to the cecum of the large intestine through the ileocecal valve. 

Chyme is a digestive enzyme. As peristaltic waves drive the chyme into the ascending and transverse colons, whatever nutrients and water that are still present are assimilated by the body. 

It is this dehydration, together with the action of peristaltic waves, that assists in compacting the chyme.

The solid waste that is produced is referred to as faeces. It will continue to migrate through the descending and sigmoid colons until it is finished. 

The large intestine is responsible for temporarily storing faeces before they are eliminated.

Functions that are specialised

The large intestine is lined by mucosa, which contains glands and goblet cells that produce mucus. 

These glands are found in Crypts of Lieberkühn, which are found in the Crypts of Lieberkühn.

These protect the intestinal wall from the profusion of anaerobic bacteria found in the colon, as well as the pressure placed on the walls by the concentrated chyme that passes through the colon (soon to become faeces).

GALT (gastrointestinal lymphoid tissue) is found in the walls of the intestines and contributes to the body’s immune system defences.

The colon contributes to the absorption of a small amount of water from the lumen (400ml/day).

Because the chyme has become extremely concentrated by the time it reaches this point, the colon must fight against a greater osmotic pressure gradient than it would otherwise encounter throughout the rest of the GIT.

In other words, it must transport water in the opposite direction of the gradient for osmosis to occur.

In addition, the colon aids in the transportation of ions.

Absorption of Water and Ions

The net absorption of sodium ions occurs in the large intestine, while the active absorption of chloride ions occurs there.

Sodium – 

This ion can be absorbed in a variety of ways, including:

The luminal membrane has an antiporter for sodium and hydrogen, which is situated on the surface of the membrane. 

The absorption of short-chain fatty acids in the colon through specialised symporters contributes to this improvement.

Chloride and bicarbonate –

The entry of sodium into the plasma results in the formation of an electrochemical gradient, which allows for the absorption of chloride to take place in the plasma environment.

At some point during the process of oxidation, chloride ions trade places with bicarbonate ions (causing net bicarbonate secretion).

In the case of water, the absorption of these electrolytes produces an osmotic gradient that allows for more water absorption.

Potassium -When potassium is absorbed in the colon, it can either be absorbed or secreted, depending on the amount of potassium left in the lumen and the electrochemical gradient established by salt absorption during digestion. 

It is most common for secretion to occur when the luminal concentration of potassium ions is less than 25 mM.

Are nutrients absorbed in the small or large intestine

Almost all of the nutrients in your meal are absorbed by the small intestine and then transported by your circulatory system to other parts of your body for storage or utilisation. 

Gut mucosa is a barrier that prevents nutrients from entering the bloodstream after they have been consumed.

Simple sugars, amino acids, glycerol, as well as some vitamins and salts, are transported to the liver via the bloodstream. 

Your liver is responsible for storing, processing, and delivering nutrients to the rest of your body when they are required.

A network of veins that transports white blood cells and a fluid known as lymph throughout your body in order to combat infection and absorb fatty acids and vitamins, is the lymph system (National Institutes of Health external link).

Sugars, amino acids, fatty acids, and glycerol are all used by your body to create the compounds that you require for energy, growth, and cell repair.

What does the small intestine use to absorb nutrients?

The small intestine is divided into three segments that serve as a conduit from your stomach to your small intestine.

When viewed as a pipe, it is difficult to conceive that an organ as narrow as the small intestine can perform such a significant function. 

It looks like a tennis court is around 250 square metres (nearly 2,700 square feet) in size, which is the absorptive surface area of the small intestine!

What is the mechanism through which this is accomplished?

This large absorptive surface area packed into a relatively small space is made possible by three characteristics of the small intestine. 

These are as follows:

• Mucosal folds
• Villi
• Microvilli

Conclusion

It is the last component of both the gastrointestinal tract and the digestive system in vertebrates, and it is also known as the large intestine or big bowel.

In this area, water is absorbed, and any remaining waste material is kept in the rectum as faeces until it is expelled by defecating.

Because the majority of the water has 

already been absorbed, the chyme that enters the colon is already highly concentrated when it arrives.

The colon is the longest section of the large intestine, and the phrases colon and large intestine are sometimes used interchangeably. 

However, most sources define the large intestine as the combination of the cecum, colon, rectum, and anal canal, among other structures.