Download What are Digestive Glands and explain its role in Digestion?

What are Digestive Glands and explain its role in
Digestion?
NIRMALA AGARWAL
The essential functions of Digestive Glands are:Salivary Glands:
In man there are three pairs of salivary glands (sub maxillary, sublingual, and parotid)
which secrete saliva. Saliva contains an enzyme called salivary amylase which breaks
down starch (complex substance) of the food into maltose (a simpler sugar). Thus, in the
mouth cavity saliva moistens the masticated food and starts digestion of carbohydrate.
Gastric Gland:
The gastric glands secrete hydrochloric acid and gastric juice which help in digestion of
food. The enzyme pepsin present in the gastric juice acts on the proteins of the food and
breaks them into smaller units called peptones and proteoses. The food then passes into
the small intestine.
Liver:
It is the largest gland of the body. It weighs 1.5 kg in man. Liver performs many
functions. As far as digestion is concerned, it secretes a fluid called bile.
Bile juice produced by the liver is stored in the gall bladder. Gall stones which are found
in the gall bladder of about 8% of the people are chiefly the concretions (depositions) of
cholesterol, bile pigments and calcium salts. Bile is yellowish greenish, alkaline fluid.
Bile emulsifies fats which help in breaking them into small globules. In this way, fat
globules are easily exposed to the action of fat-hydrolyzing, enzymes. The acidic food
coming from the stomach becomes alkaline, when it is mixed with the bile. It is an
extremely important step which ensures further digestion of the food. The digestive
enzymes that are brought in the duodenum and ileum can catalyse the breakdown of
food only in alkaline medium.
Pancreas:
It is the second largest gland of the body. It lies in the fold of duodenum. It is yellowish.
It secretes pancreatic juice.
Pancreatic duct pours pancreatic juice into the duodenum. Pancreatic juice contains a
number of digestive enzymes. These include trypsin and chymotrypsin for the
breakdown of proteins; amylase for the splitting of polysaccharides; lipase for the
breakdown of fats and nuclease for the breakdown of nucleic acids. These enzymes
catalyse the breakdown of different constituents of food but not sufficiently enough to
break all of them into their units.
Intestinal Glands:
The final step of digestion takes place in the ileum. There are numerous smaller glands
occupying the walls of the small intestinal tract. These glands secrete what is termed
intestinal juice or succus entericus. The intestinal glands are in the form of sunken pits
or crypts which are interspersed among the finger-like villi. The digestive enzymes in the
intestinal juice include carboxypeptidase and aminopeptidase which break small
peptides into amino acids; sucrose, maltase and lactase which brak disaccharides into
respective monosaccharides; lipase which breaks lipids into fatty acid and glycerol; and
nuclease which breaks nucleic acids into nucleotides.