What are the Functions of the Small Intestine

 What are the Functions of the Small Intestine


The small intestine is also a part of the alimentary tract.

The small intestine is also termed as the small bowel.

The role of the small intestine begins after the stomach in the digestive track.

The small intestine is a long, narrow, and coiled tube that extends from the stomach to the large intestine.

It is 6 to 7 metres long.

It is responsible for the majority of digestion and absorption.

It lies in the abdominal cavity and is surrounded by the large intestine.

In this article, we will learn the functions of the small intestine. By the end of the article, you will know very well what the functions of the small intestine are.

Different digestive organs play a particular role in the digestion of food.

We have learned in the previous articles: the functions of the pancreas in the digestive system; the functions of the liver in the human body. For more clarity, you can also read those articles.

What Are the Functions of the Small Intestine? (overview)

  • secretes intestinal juice.
  • It completes the chemical digestion of proteins, carbs, and fats.
  • It produces hormones like CCK and secretin.
  • Does absorption of the nutrients
  • It allows forward movement of food by peristalsis.
  • It protects against infection caused by microrganisms by lymph follicles.

Functions of the Small Intestine (In Detail)

Secretes Intestinal Juice

After passing through the stomach, the food moves towards the small intestine in the form of chyme.

Food is pushed down into the duodenum (a "c" shaped section of the small intestine that connects to the stomach).

Here, food is mixed with small intestine juice, consisting of bile juice, pancreatic juice, and intestinal juice.

We have already talked about bile juice and pancreatic juice. Let us know about intestinal juice.

Intestinal juice is alkaline in nature. Its components are water, mucus, electrolytes, and enzymes. Brunner's gland, present in the duodenum, secretes alkaline mucus into the duodenum to protect it from the corrosive HCl.

There are crypts between two adjacent villi present in the small intestine called the Crypts of Lieberkuhn.

These are of two types. Goblet secretes Mucus and Enterocytes secretes water and electrolytes Cl⁻ and HCO₃⁻.

Bicarbonate alkalizes the pH of the food. And the chloride ion reacts with the positive ions (Na+ ions) present in the food to form a salt and neutralises the pH.

Completes the Chemical Digestion of Proteins, Carbs, and Fats

Peptidase enzymes act on proteins to break them into small peptides and amino acids.

Intestinal liapse acts on fat and breaks it down into fatty acids and glycerol.

The Enterokinase enzyme activates trypsinagen to tripsin.

Nucleotidase enzymes help to digest DNA and RNA present in food.

Carbohydrate-digesting enzymes convert sucrose into glucose and fructose, lactose into glucose, galactose and maltose into glucose.

Basically, it converts complex sugars into simpler forms so that they become easy to absorb for the body.

Last words

Hopefully, by now you will be clear about what the functions of the small intestine are.

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Thanks for reading!

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