Explain the digestion in the small intestine .

Explanation

The bile, pancreatic juice and intestinal juice are the secretions released into the small intestine. Movements generated by the muscularis layer of the small intestine helps in the thorough mixing of the food with various secretions in the intestine and thereby facilitate digestion. The pancreatic juice contains enzymes such as trypsinogen, chymotrypsinogen. carboxypeptidases, pancreatic amalyses, pancreatic lipases and nucleases. Trypsinogen is activated by an enzyme, enterokinase, secreted by the intestinal mucosa into active trypsin, which in turn activates the enzyme chymotrypsinogen in the pancreatic juice. The bile contains bile pigments (bilirubin and biliverdin) as the break down products of hemoglobin of dead RBCs, bile salts, cholesterol and phospholipids but has no enzymes. Bile helps in emulsification of fats. Bile salts reduce the surface tension of fat droplets and break them into small globules. Bile also activates lipases to digest lipids. Proteins and partially digested proteins in the chyme on reaching the intestine are acted upon by the proteolytic enzymes of pancreatic juice. Trypsin hydrolyses proteins into polypeptides and peptones.
while chymotrypsin hydrolyses peptide bonds associated with specific amino acids. The pancreatie amylase converts glycogen and starch into maltose. Lipase acts on emulsified fat (triglycerides) and hydrolyses them into free fatty acid and monoglycerides Monoglycerides are further hydrolysed to fatty acid and glycerol. Nucleases in the pancreatic juice break the nucleic acid into nucleotides and mucleosides. The secretions of the Brunner's gland along with the secretions of the intestinal glands constitute the intestinal juice or succus entericus The enzymes in the intestinal juice such as maltase, lactase, sucrase (invertase), dipeptidases, Tipases, nucleosidases act on the breakdown products of bile and pancreatic digestion,
Maltose `overset ("Maltase") to ` glucose + glucose
Sucrose ` overset("Sucrase") to ` glucose + fructose
Lactose ` overset("Lactase") to` glucose + galactose
Dipeptides, Tripeptides `overset("Peptidase") to` amino acids
Nucleotides ` overset(" Nucleosidase") to` Nucleoside + Phosphoric acid
Nucleoside ` overset("Nucleosidase") to ` Sugar + Nitrogen base
Diglycerides and monoglycerides ` overset("Lipases") to` Fatty acids + glycerol
The mucus along with the bicarbonate ions from the pancrcas provides an alkaline medium` (pH 7.8)` for the enzymatic action. As a result of digestion, all macromolecules of food are converted into their corresponding monomeric units.
`" Carbohydrates " to " monosaccharides " `
(glucose, fructose and galactose)
` " Proteins " to " amino acids " `
` " Lipids " to " fatty acids and glycerol " `