Absorption Of Digested Food In The Small Intestine

We eat different kinds of food every day and it is a compulsory and important steps that the food gets digested and absorbed, all the nutrients and minerals that our body gets is through the food that we consume the energy that is provided by those food is getting absorbed by the body the moment it enters, now absorption and assimilation of food are two different processes. In absorption and assimilation of food we see that the food enters the alimentary canal which gets broken into simpler substances with the help of the enzyme enzymes that are produced by the body and this process is known as assimilation of food. We have read this since a very early age that saliva helps in breaking down the food and makes the process of digestion easier right from the mouth.

The most common example would be carbohydrates which are broken down into simpler units by saliva in the buccal cavity. The proteins that we consume which are high in calorific value are broken down into simpler compounds by the action of pancreatic juice in the small intestine, the fats are similarly broken down by the action of bile which is also present in the small intestine and additionally small intestine helps in the absorption of food in various ways, the entire process would come under a simulation of food.

Now we go on to define absorption so what happens during absorption is that the digested products are transported into the blood or lymph call lymphatic tissue is through the mucous membrane, the absorption of food is achieved by different mechanisms which are simple diffusion, active transport, facilitated transport and passive transport.

Before we go ahead with the explanation of these processes we will understand what diffusion means. We can define diffusion as the intermingling of substances by the natural movement of their particles into a wider term.

Simple Diffusion

In simple diffusion the movement of salute from the higher concentration of anything to the lower concentration through the membrane is produced or performed for example after digestion, a few monosaccharides diffuse into the bloodstream based on its concentration gradient a few examples would be glucose, amino acids and certain irons like chloride.

Active Transport

Active transport is just the opposite of simple diffusion; it may be defined as a process where the movement of the salute from the lower concentration towards the higher concentration takes place at the expense of energy, which means that there is some utilization of energy that takes place while the transformation happens. The process of electrolytes like any Na ions engages in the process of active transport as they are absorbed into the blood.

Facilitated Transport

This can be defined as the process of movement of solute across the biological membrane present in the body with the help of certain specific carrier proteins. Through facilitated transport, some digested amino acids and glucose are absorbed into the blood or bloodstream with the help of this method.

Passive Transport

Just like the term sounds, passive transport is a process where the movement of solute across a cell membrane takes place without the requirement of energy or expenditure of energy. This process usually takes place after digestion when simpler food substances are absorbed into the blood.

Now the process of absorption of food is not always easy as there are some digested food or digested products from fats that cannot be absorbed into the blood for example fatty acids and glycerol so there are certain components known as micelles component complex which attaches to micelles, which are small droplets from the complex, these component complexes are formed into chylomicrons which are small protein-coated fat globules present in the body all the cells, these, in turn, move into the lymphatic vessels and release the digested products into the bloodstream and finally the food that is digested and absorbed reach is the tissue which is further utilised for the activities that are required by the body and this again explains the process of a simulation.

Now the process of absorption starts at the mouth where digestion begins with chewing, the mucus that is used helps in moistening the food and the enzyme that is produced is amylase, which partially digests polysaccharides also known as starch food. After this is done the food reaches the stomach through the pathway which consists of fairings and esophagus now we all know that the stomach stores and digests food macromolecules into a solution called chyme. Now the lining is present in the glands of the stomach to secrete hydrochloric acid that is responsible for dissolving food particles and protein-digesting enzymes called pepsin. The final stages of digestion happen in the small intestine which is further divided into three segments known as the duodenum, jejunum, and ileum.

Now certain monosaccharides, amino acids, and mineral salts are not easily absorbed but then this process happens by transport and mediated processes where the fatty acid and water diffuse passively.

Undigested material is passed to the large intestine, although it is temporarily stored and concentrated by the absorption of salt and water while it stays there and after it is ready for use we see the contractions of the rectum, the last part of the large intestine which explains the fickle matter through the anus thus ending the process of digestion and absorption as well.

The digestive system is a special set of organs that help break down the food we eat into smaller composite particles that are then absorbed into the bloodstream. Proteins called digestive enzymes aid the process and help to catalyse a series of chemical reactions. Before we proceed, let's learn what is meant by digestion. 

Digestion is a complex physicochemical process that transforms large particles of food into smaller, simple substances. This is followed by the absorption and assimilation of digested food that begins with the walls of the alimentary canal.

Absorption in Digestion

The process by which digested food molecules are absorbed into the bloodstream and transported to different parts of the body is known as absorption. Absorption of food begins with the small intestine. The digested food molecules pass through the walls of the small intestine and then into the bloodstream.

Once the food particles reach the bloodstream, they are transported throughout the different parts of the body, wherever necessary. 

Only smaller, soluble food molecules can pass through the walls of the small intestine, whereas larger food molecules cannot pass through as they are insoluble.

Mechanism of Absorption 

During the absorption process in digestion, a network of mucous membranes help carry the digested, soluble food molecules into the bloodstream or lymph. The process of absorption involves the following steps.

• Diffusion

• Active Transport

• Facilitated Transport

• Passive Transport

Let us revise a few important concepts with the following exercise.

Pop Quiz 1

1. The absorption of food takes place in the ___________.

1. Large intestine

2. Mouth

3. Small intestine

4. None of the above

The Following Points Help Illustrate the Importance of Absorption:

1. The body needs to extract ingredients from the food you eat to ensure its proper functioning.

2. As food particles break down into smaller particles, the process of absorption ensures that these particles are carried into the bloodstream.

3. It is only through the process of absorption that digested food particles reach various cells, tissues and organs of our body.

4. Blood carries nutrients like sugars and amino acids from the absorbed food into the liver where they are processed.

5. From the liver, these nutrients are delivered to other parts of the body where they are required.

For more on absorption definition in biology and related processes, refer to our free PDF notes, practice papers and revision notes, available on the website. Install the Vedantu app today, and have your doubts instantly clarified.