Important Notes on Digestion and Absorption for NEET

Digestion and Absorption: Important Notes for Biology NEET

The concepts of digestion and absorption are among the most crucial topics in NEET’s scope, which touches upon several important topics. Since the chapter is quite extensive, revising it at the last moment may seem challenging.

To remedy this, you can refer to important notes of biology for NEET digestion and absorption for quick and effective revision. It will not only enable you to glance through the important concepts but will also help to identify crucial points of digestion and absorption NEET. 

With that being said, let us find out more about these concepts below!

What is Digestion?

It is the process through which complex food is converted into a simpler form to facilitate absorption of nutrients and release of energy in the body. 

What is the Digestive System?

The digestive system includes the alimentary canal and digestive glands. The alimentary canal which runs down from the oesophagus to the rectum has four layers, namely, serosa, mucosa, muscularis and submucosa.

These following make up the alimentary canal –

  • Mouth.

  • Pharynx.

  • Stomach.

  • Small intestine.

  • Large intestine.

Digestive Glands

These glands play a vital role in digestion. Typically, there are 5 types of glands, and they are as follow –

  1. Salivary glands. 

  2. Gastric Glands.

  3. Intestinal Glands.

  4. Pancreas. 

  5. Liver.

Important notes of biology for NEET digestion and absorption explains these glands and their functions in brief and helps to understand the same effectively.

Digestion of Food

Digestion commences in the mouth where the masticated food gets mixed with saliva. In turn, it creates bolus or small mass of food which moves down the pharynx and oesophagus with the help of deglutition or swallowing.

Subsequently, the digestive enzymes present in the alimentary canal get mixed with food and initiates the process of digestion.

These pointers highlight some of the most noteworthy steps in the process of digestion.

  • Chemical digestion commences in the oral cavity with the help of salivary enzymes like lysosomes and amylase.

  • Mucosa layer in the stomach contains gastric glands which have mucous neck cells, peptic of chief cell and parietal cells. 

  • Mucous cells secrete mucus, while the peptic of chief cells is responsible for secreting proenzyme pepsinogen. Additionally, the oxyntic or parietal cells secrete HCL, which is responsible for converting pepsinogen into pepsin for digesting protein.

  • Bicarbonates and mucus found in the gastric juice lubricates and protects the inner wall of the stomach against the corrosion caused by HCL. 

  • Small intestine releases pancreatic juice, bile and intestinal juice. Notably, the pancreatic juice has inactive trypsinogen, lipases, nucleases, chymotrypsinogen, amylases and procarboxypeptidase.

  • Enterokinase which is an enzyme, activates Trypsinogen into trypsin which subsequently activates other enzymes found in intestinal juice.

  • Bile salts, bilirubin and biliverdin, cholesterol and phospholipids aid the emulsification of fats. 

Most digestion and absorption class 11 notes cover these pointers in detail and explain their importance as well. Read through for a better understanding and quality revision. 


This process converts bio-macromolecules into simpler forms in the duodenum and gets further absorbed in the intestine’s ileum and jejunum. Notably, the food is absorbed through diffusion because of the concentration gradient, whereas water is transported because of osmosis gradient.

Subsequently, through assimilation, the nutrients are absorbed and transported to different body parts via blood and lymph. 

Read more about absorption and its role in the important notes of biology for NEET digestion and absorption.

Digestive System Disorders

Several bacterial, viral, parasitic and protozoan infections are responsible for the inflammation of the intestine and are among the primary causes of digestive disorders. 

This Table Explains the Common Disorders of the Digestive System.





More precisely, it is a liver disorder, wherein a large quantity of bilirubin pigment is found in the extracellular fluid. 


It is a common disorder which occurs due to incomplete digestion of food and is often accompanied by acid regurgitation, nausea, pain, heartburn, etc. 


It is responsible for irregular bowel movements. 


Diarrhoea is often responsible for the inadequate absorption of nutrients. 


Continuous vomiting leads to dehydration. 

A weak digestive system leads to poor absorption of nutrients, which in turn leads to protein-energy malnutrition, especially in children. Two of the most prevalent diseases which occur due to malnutrition include marasmus and kwashiorkor. 

You can find out more about digestive disorder in Class 11 Biology digestion and absorption notes.  

Plan Your Revisions for Better Results!

NEET is the most important stage for students who intend to gain admission in the medical or dental course. It is also considered as one of the toughest entrance exams.

Since success in NEET depends entirely on preparation, it’s time for you to make the most of these last few weeks before the exam. Incorporate smart ways of revision tools and techniques to improve your preparation. 

For instance, refer to important notes of biology for NEET digestion and absorption for a quick yet impactful revision. Also, the digestion and absorption NEET notes will ensure that you do not miss out on any relevant topic.

FAQ (Frequently Asked Questions)

1. What is the difference between Digestion and Absorption?

Ans. Digestion is the process wherein, food particles are converted into a small form which can be readily absorbed by the body to produce energy and for providing nourishment. In case of absorption, nutrients from digested food molecules are absorbed readily by the small intestine. 

2. What are the different Types of Digestive Glands?

Ans. There are 5 types of digestive glands – i. Salivary glands, ii. Gastric glands, iii. Intestinal glands, iv. Pancreas, and v. Liver. 

3. Which is the Largest Digestive Gland? Explain Its Function.

Ans. The largest digestive gland is the liver, which is located in the abdominal cavity and below the diaphragm. Liver’s primary function is to detoxify metabolites and synthesise protein; in turn, it aids the process of digestion.