Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

Current Affairs & General Knowledge

UPSC : Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

The document Digestive System - Notes, Biology, IAS UPSC Notes | EduRev is a part of the UPSC Course Current Affairs & General Knowledge.
All you need of UPSC at this link: UPSC

Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

 

Digestive System in Humans

  • The process of converting food into energy giving substances is carried out by this system.
  • The digestive system comprises the alimentary canal and the associated digestive glands like liver and pancreas.

Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

 

Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

 

1. Buccal Cavity

  • In the mouth salivary glands secrete saliva which contains the enzyme Ptyalin (or salivary amylase)
  • Here the food is called bolus.
  • Also contains Lysozyme which kills bacteria.

Teeth

  • Teeth : They are produced in two sets – Temporary and Permanent.
  • The teeth are of four types :
    • Incisors,
    • Canines,
    • Premolars and
    • Molars.

Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

 

Dental Formula: 2123 / 2123.

  • This means that there are 2 incisors, 1 canine, 2 Premolars and 3 molars in half of the upper jaw and exactly the same arrangement in half of the lower jaw.
  • This figure is doubled to get the full number, i.e. 32.
  • The premolars and the molars are called the grinding teeth. The last molars are called the wisdom teeth.
  • In elephants, incisors of the upper jaw grow into huge tusks.
  • Canines are very large in predators such as cat, dog and lion.

Structure of a Tooth: 

A tooth consists of 3 Regions :

  • Crown, Neck and Root:
  • The crown is the exposed part. It is covered by a shining material called Enamel.
  • Enamel is the hardest substance in the human body

Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

 

2. Pharynx

  • Links Buccal Cavity to Oesophagus.
  • Food is carried by peristaltic movement [Peristalsis is a series of wave of contraction that passes from end to other and is meant for pushing the food].
  • Trachea opens into Pharynx through an aperture called Glottis.
  • It also receives the opening of the Eustachian Tubes from the middle ear through an Aperture called Gullet.

Digestive System - Notes, Biology, IAS UPSC Notes | EduRev

 

4. Stomach

  • Oesophagus opens into it.
  • The opening is guarded by a valve which checks the regurgitation of food.
  • In stomach, the food is called chyme.
  • Has 3 Parts :
    • Fundus
    • Cardiac
    • Pyloric
  • It is a warehouse where food can be stored to await the main process of digestion.
  • Gastric juices produced in the stomach help in digestion of food.
  • Also contains HCI which kills bacteria and provides acidic medium.
  • Besides it activates pepsinogen to pepsin and prorennin to rennin.
  • It is a warehouse where food can be stored to await the main process of digestion.
  • Gastric juices produced in the stomach help in digestion of food.
  • Also contains HCI which kills bacteria and provides acidic medium.
  • Besides it activates pepsinogen to pepsin and prorennin to rennin.

5. Small Intestine (Duodenum + Jejenum + Ileum)

  • Here the food from the stomach is mixed with bile (from liver) and pancreatic juice (from pancreas) and moves forward by peristaltic movement.
  • Duodenum receives the bile – pancreatic duct formed by the union of bile duct and pancreatic duct.
  • Both jejunum and ileum have numerous figure like projections called the villi.
  • The villi contain blood vessels to receive the products of digestion after they have been absorbed.
  • Bile doesn’t take direct part in digestion of fat; it just makes the food alkaline. (It is stored in gall bladder)
  • Pancreatic juice contains several enzymes, which act on proteins, carbohydrates and fats.

6. Large Intestine (Caecum + Colon + Rectum)

  • It receives undigested material from the small intestine and absorbs water.
  • Caecum is the diverted part of intestine.
  • Cellulose digestion takes place in it.
  • It is very large in herbivores.
  • Vermiform appendix is a part of caecum, which produces antibodies. Both caecum and appendix are vestigial in humans.
  • The remaining waste material is sent to rectum and discharged through anus.

Pancreas

Intestinal Glands

 

Secreted by

Enzymes

Acts on

Products

Salivary Glands

Ptyalin (Salivary Amylase)

Starch, Glycogen, Dextrins

Maltose, Isomaltose, 'Limit' Dextrins

Gastric

Pepsin (Activated from Pepsinogen by HCI)

Proteins, Calcium Paracaseinate

Peptones

Rennin (Activated from Prorennin by HCI)

Casein

Paracasein and Whey Proteins

Gastric Lipase

Fats

Fatty Acids and Monoglycerides

Pancreas

Trypsin (Activated from Trypsinogen by Enterokinase)

Proteins

Peptides

Chymotrypsin (Activated from Chymotrypsinogen by Trypsin)

Proteins, Casein

Peptides, Paracasein (curd)

Pancreatic Amylase

Starch, Glycogen, Dextrins

Maltose, Isomaltose, 'Limit' Dextrins

Pancreatic Lipase

Emulsified fats

Fatty Acids, Glycerol, Monoglycerides, Diglycerides and Triglycerides

Carboxypeptidases (Activated from Procarboxypeptidases by Trypsin)

Peptides

Amino Acids and Dipeptides

DNAse

DNA

Deoxyribonucleotides

RNAse

RNA

Ribonucleotides

   

Intestinal Glands

Intestinal amylase

Starch, Glycogen, Dextrins

Maltose, Isomaltose, 'Limit' Dextrins

Maltose

Maltose

Glucose

Isomaltase

Isomaltose

Glucose

'Limit' Dextrinase

'Limit' Dextrins

Glucose

Invertase (Sucrase)

Sucrose

Glucose, Fructose

Lactase

Lactose

Glucose, Galactose

Intestinal Lipase

Emulsified fats (Tri-, Di-Monoglycerides)

Fatty Acids, Glycerol

Nucleotidases

Nucleotides

Nucleosides and Inorganic Phosphates

Nucleosidases

Nucleosides

Nitrogenous Bases, Pentose Sugars

 

Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Related Searches

IAS UPSC Notes | EduRev

,

Extra Questions

,

IAS UPSC Notes | EduRev

,

shortcuts and tricks

,

Summary

,

Digestive System - Notes

,

video lectures

,

past year papers

,

study material

,

Semester Notes

,

Objective type Questions

,

Sample Paper

,

Free

,

Biology

,

Biology

,

pdf

,

Previous Year Questions with Solutions

,

Viva Questions

,

Digestive System - Notes

,

Digestive System - Notes

,

mock tests for examination

,

Exam

,

ppt

,

Biology

,

practice quizzes

,

IAS UPSC Notes | EduRev

,

MCQs

,

Important questions

;