Digestion and Absorption

Edited By Team Careers360 | Updated on May 11, 2022 02:31 PM IST

Digestion is the process of chemical breakdown of the ingested meals into absorbable molecules. Absorption refers back to the motion of vitamins, water, and electrolytes from the lumen of the small intestine into the cellular intestine, then into the blood.

What is Digestion?

Digestion

Digestion may be defined because of the procedure via means of which the meals we devour pass via our bodies and is directed toward the functions of presenting the frame with electricity or constructing new mobile additives and tissues, consisting of muscle or fats. The components of meals that the frame can not use and additionally different wastes from the frame are removed withinside the shape of excrement.

Latest: NEET 2024 Paper Analysis and Answer Key

Don't Miss: Most scoring concepts for NEET | NEET papers with solutions

New: NEET Syllabus 2025 for Physics, Chemistry, Biology

NEET Important PYQ & Solutions: Physics | Chemistry | Biology | NEET PYQ's (2015-24)

Digestion also can be called a shape of catabolism that may be divided into tactics primarily based totally on how meals are damaged. Chemical digestion can be divided into two basic types.

Mechanical digestion may be described because of the bodily breakdown of big portions of meals into smaller portions that may be accessed via means of digestive enzymes. In chemical digestion, enzymes spoil down meal debris into small molecules that the frame can absorb. water from undigested food is absorbed mainly in the large intestine. Food travels through the digestive tract for several hours before reaching the big intestine. It is necessary to wipe up the undigested food remains. The big intestine is where the goblet cells ingest the excess water from the dietary residue.

Mechanism of Digestion

As the meal enters the mouth it undergoes mechanical digestion via means of the movement of mastication (chewing) and it additionally will become whilst it's far in contact with saliva. Saliva incorporates salivary amylase which begins off evolving the digestion of starch withinside the meals.

After the meals undergo mastication and starch digestion, it is going to be withinside the shape of a small, spherical slurry mass referred to as a bolus. It travels down the oesophagus and into the belly via means of the movement of peristalsis.

In the belly, gastric juices provoke protein digestion. These juices particularly include pepsin and hydrochloric acid. As the HCl may also harm the belly wall, mucus is secreted via means of the belly which gives a slimy layer that acts as a guard in opposition to the dangerous outcomes of the acid.

Protein digestion takes place on equal time through mechanical blending via means of peristalsis permitting the mass of meals to combine with the digestive enzymes.

After a while, a thick liquid referred to as chyme is produced which enters the duodenum which then mixes with the digestive enzymes from the pancreas and bile juice from the liver after which passes via the small gut. After the chyme is absolutely digested, it's far absorbed into the blood.

It needs to be cited that 95% of nutrient absorption takes place withinside the small gut. Water and minerals are reabsorbed lower back into the blood withinside the big gut in which the pH is barley acidic approximately 5.6 ~ 6.9. Some vitamins, consisting of nutrition K and biotin, which can be produced via means of microorganisms inside the colon also are absorbed into the blood withinside the colon. Waste fabric exits from the rectum at some stage in defecation.

What is Absorption?

Absorption:

In general, food absorption refers to the act or process of absorbing or assimilating. Absorption in biology refers to the process of absorbing or assimilating substances into the cell or across tissues and organs. absorption of food takes place in the small intestine.

The important characteristic of the small gut is the absorption of minerals and vitamins determined in meals. Digested vitamins by skip through the blood vessels withinside the wall of the gut via a procedure of diffusion.

The mucosa or the internal wall of the small gut is coated with columnar epithelial tissue. The absorbed minerals and vitamins are transported via means of blood vessels to unique components of the human frame in which they may be used to construct proteins, carbohydrates, and lipids required via the means of our frame. The meals that stay undigested and unabsorbed usually pass through the colon or the big gut.

Carbohydrates

Digestion and absorption of carbohydrates:

Digestion

There are 3 carbohydrate commodities that can be absorbed via means of the small gut; glucose, galactose, and fructose.

Digestion of carbohydrates is initiated inside the mouth, facilitated via means of salivary amylase. The majority of carbohydrate digestion takes place withinside the small gut. The important enzyme is pancreatic amylase, which yields disaccharides from starch via means of digesting the alpha 1-four glycosidic bonds. The disaccharides produced (maltose, maltotriose, and α-dextrins) are all transformed to glucose via means of brush border enzymes.

Disaccharides going on clearly in meals do now no longer require amylase to interrupt them down. Brush border enzymes (lactase, sucrase, trehalase) hydrolyze those compounds into molecules of glucose, galactose, and fructose.

NCERT Notes Subject Wise Link:

Absorption

Glucose and galactose are absorbed throughout the apical membrane via means of secondary energetic transport (alongside Na+) via the Sodium-Glucose cotransporter (SGLT1). Both glucose and galactose go out the cellular through GLUT2 receptors throughout the basolateral membrane into the blood. Fructose enters the cellular via means of facilitated diffusion through GLUT5 and is transported into the blood through GLUT2 receptors.

Protein

Protein digestion and absorption:

Digestion

Digestion of protein starts off and evolves inside the belly with the movement of pepsin, which breaks protein into amino acids and oligopeptides. The procedure of digestion is finished withinside the small gut with a brush border and pancreatic enzymes. They cut up the oligopeptides into amino acids, dipeptides, and tripeptides.

Ncert Books Link:

Absorption

Amino acids are absorbed through a Sodium cotransporter, in a comparable mechanism into monosaccharides. They are then transported through the basolateral membrane through facilitated diffusion. Di and tripeptides are absorbed through separate H+ established cotransporters and as soon as withinside the cellular are hydrolyzed to amino acids.

fats absorption

Once fat reaches the small intestine, it is mostly digested. The bulk of nutrients are also absorbed here. Enzymes are produced by your pancreas to break down lipids, carbs, and proteins. Bile is produced by the liver and aids in the digestion of lipids and some vitamins.

Digestion and absorption of lipids

The hydrolysis of dietary fat in the intestinal lumen is followed by the uptake of hydrolyzed products by enterocytes. Endoplasmic reticulum re-synthesizes lipids, which are then either released with chylomicrons and high density lipoproteins or retained as cytoplasmic lipid droplets.

NCERT Solutions Subject wise link:

NEET Highest Scoring Chapters & Topics

Know Most Scoring Concepts in NEET 2024 Based on Previous Year Analysis

Know More

NCERT Exemplar Solutions Subject wise link:

Frequently Asked Questions (FAQs)

1. Where is Protein Digested?

Protein digestion takes place inside the belly and duodenum. Pepsin, which is secreted via means of the belly, and trypsin and chymotrypsin secreted via means of the pancreas, spoil down meals proteins into polypeptides.

The digestive enzymes are normally secreted as their inactive precursors referred to as zymogens. For example, trypsin is secreted via way of means of the pancreas withinside the shape of trypsinogen, which is activated withinside the duodenum via way of means of enterokinase to shape trypsin. Proteins are then broken up into smaller polypeptides by trypsin.

2. Bile juice incorporates no digestive enzymes, but it's far essential for digestion. Why?

Bile juice is essential for digestion. It is a digestive juice that is produced via means of the liver. Even though it has no digestive enzymes, it has an important position to play in fat digestion. Bilirubin and biliverdin are the 2 bile salts that can be found in bile juice, which disintegrates big globules into smaller globules such that the pancreatic enzymes can act on them easily. This phenomenon is called the emulsification of fats. The bile juice is likewise recognized to make the medium alkaline and is concerned with the activation of lipase.

3. What might manifest if HCl has been now no longer secreted withinside the belly?

The partitions of the belly secrete hydrochloric acid, which dissolves fragments of meals and builds an acidic environment. This medium enables the conversion of pepsinogen into pepsin. Pepsin performs an important position in protein digestion.

Pepsin might be inactivated if HCl has now no longer been secreted withinside the belly which might have an impact on the digestion of proteins. To digest proteins, a pH balance of eight is necessary. HCl provides this balance.

4. Explain the phrases codon and diphyodont.

Every tooth in humans is embedded in a socket of the jaw bone. This attachment of enamel is called codont. Most mammals and humans produce units of enamel during their lifetime. First, as a fix of milk enamel or deciduous enamel which can be transient, and 2nd a fix of grownup enamel which can be everlasting. The transient milk enamel is changed via means of everlasting grownup enamel. This dentition is called diphyodont.

5. What is Digestion?

Digestion may be defined because of the procedure via means of which the meals we devour pass via our bodies and is directed toward the functions of presenting the frame with electricity or constructing new mobile additives and tissues, consisting of muscle or fats. absorption of digested food takes place in the small intestine. The digested food is absorbed by the villi in the small intestine. The components of meals that the frame can not use and additionally different wastes from the frame are removed withinside the shape of excrement.

6. Explain the terms Thecodont and Diphyodont.

Thecodont: Inhuman, every tooth is embedded in a socket of the jaw bone. Such enamel is defined as the thecodont.

Diphyodont: The majority of mammals such as humans shape units of enamel at some stage in their life, a fix of transient milk or deciduous enamel changed via means of a fix of everlasting or grownup enamel. This form of dentition is referred to as diphyodont.