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Digestive Glands - Salivary Gastric & Intestinal | X | Biology | Life Processes | Digestion & Absorption | BurnYourBooksOpenYourMind | BYBOYM | Foundation4Neet | NCERT | NEET | Biology | BOTANY | Zoology | - NCERT CLASS10 CHAPTER 1

This is the Seventeenth topic in the first chapter of Biology for NEET FOUNDATION X. The First chapter is Life Processes. #F4NXC01T17

What you'll Learn?
 Digestive Glands
 Associated Glands
 Salivary Glands
 Parotid Glands
 Submaxillary Glands
 Submandibular Glands
 Sublingual Glands
 Gastric Glands
 Intestinal Glands
 Chief Cells
 Peptic Cells
 Zymogenic cells
 Mucous neck cells
 Goblet cells
 Intrinsic Factor
 Extrinsic Factor
 Cobalamin
 Chymosin
 Rennin
 Milk Curdling
 Cheese

What are Digestive Glands?

The human digestive system can be divided into two components.
The alimentary canal which is a long functionally differentiated digestive tube.
Associated Glands : These glands secrete juices that aid in digestion. These are the salivary glands, liver, and pancreas.


SALIVARY GLANDS

The salivary glands are exocrine glands i.e., they pour their secretions through a system of ducts.

In humans, there are 3 pairs of salivary glands:

Parotid Glands: Largest glands, present below and in front of the ears.
Submandibular(Submaxillary) Glands: Located at the angles of the lower jaw.
Sublingual Glands: Smallest glands, Located below the tongue.


Together these glands secrete about 1-1.5 L of saliva every day. The ph of saliva is 6.2 -7.6.
The composition of saliva is
99% water,
electrolytes(Na+, K+, Cl-, HCO3-),
salivary amylase(ptyalin) and
lysozyme.

Functions of Saliva:
The lysozyme present in saliva acts as an antibacterial agent that prevents infections.
The enzyme present in saliva i.e., salivary amylase or ptyalin digests starch into a disaccharide, maltose.
It maintains optimum pH in the oral cavity and protects teeth from acid produced by bacteria.
It moistens and lubricates the food.


GASTRIC GLANDS

There are about 35 million gastric glands present in the mucosa layer of the stomach wall. Their combined secretion is termed gastric juice. The pH of gastric juice is 2-3(highly acidic).

The gastric glands have the following types of cells:
Peptic or chief or zymogenic cells: Secrete the proenzyme pepsinogen, a protein-digesting enzyme.
Goblet cells or mucous neck cells: Secrets mucus that protects the inner lining of the stomach wall from the degrading action of hydrochloric acid present.
Parietal or oxyntic cells: Secrete HCl and Intrinsic factor. Intrinsic factor is also known as cobalamin binding intrinsic factor or gastric intrinsic factor(GIF). It is essential for the absorption of Vitamin B12 , also known as cobalamin.




Functions of HCL:
It softens the food
It activates the proenzyme pepsinogen into pepsin.
It disinfects the food by killing most of the harmful bacteria.
It makes the food acidic(pH 1.8) to facilitate the action of the enzyme pepsin.



Intestinal Glands

The walls of the small intestine contain numerous glands that secrete intestinal juice or succus entericus. The enzymes present in succus entericus finally convert proteins into amino acids, carbohydrates into monosaccharides, and fats into glycerol and fatty acids.

The digested food is absorbed by the walls of the small intestine.

Maltose → Glucose
Peptides and Peptones → Amino acids
Emulsified fats → Glycerol + Fatty acid

Do You Know?

G-cells are neuroendocrine cells that secrete and store the hormone gastrin. Gastrin is a peptide hormone that promotes mucosal growth, gastric motility, and HCl secretion.
Rennin or chymosin is a proteolytic enzyme of great importance. It is synthesized by chief cells in the stomach of some animals and plays a vital role in their survival.
Rennin plays an important role in the coagulation or curdling of milk. In young ones, it allows digestion of nutrients that otherwise would pass on from the stomach without initial digestion, if milk is not coagulated.
Chymosin is secreted in the neonatal stomach of animals like pigs, cats, rats, and ruminant animals such as cattle, goats, camels, etc.
In Humans, rennin is not found. Instead, pepsin plays the role of curdling milk.
Chymosin or rennin is widely used in cheese production.

Chapters
0:00 Introduction
0:17 Digestive Glands
0:41 Salivary Glands
2:18 Gastric Glands
4:04 INtestinal Glands
4:55 Do you Know?

Check the below link for the video on Histology of Alimentary Canal.
   • Histology of Alimentary Canal - English | ...  

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