Lipid digestion in animals Lipids make up a large portion of diet in carnivores, where as they form only a minor portion of diets in herbivores. Primary dietary lipid is triglyceride; other lipids include cholesterol and cholesterol esters from animal sources, waxes from plant sources and phospholipids from both plant and animal sources. Lipid digestion occurs in four phases; emulsification, hydrolysis, micelle formation […]

Protein digestion Dietary, endogenous, microbial and shed mucosal cells proteins are capable of being hydrolyzed by endopeptidases, the proteolytic enzymes present in gastric , pancreatic  and intestinal juices break the proteins at internal peptide points. In the luminal phase of digestion, gastric proteases (eg. pepsin and rennin) and pancreatic proteases (eg. trypsin, chymotrypsin, carboxy peptidase a

Chemical digestion of nutrients Chemical digestion of each major nutrient is by hydrolysis glycosidic bonds in carbohydrates, peptide bonds in proteins, ester bonds in fats and phophodiester bonds in nucleic acids by the insertion of  water molecule. Hydrolysis of nutrients in the digestive tract is catalysed by the action of enzymes secreted by salivary, gastric and pancreas glands. These glands pour their enzymes

Structure of villi in animals Surface area of the small intestine is enormously increased by large folds of mucosa known as plica circularis to facilitate contact between mucosa and lumen contents. The mucosal surface area is covered with finger-like epithelial projections called as villi to increase the surface area by about 10 to 14 fold. The villi

Functions of gall bladder Storage of bile and concentrating the bile. Delays the absorption of bile salts from the intestine by the addition of mucin to the bile. Prevents excess absorption of bile. Assisting stabilization of fat emulsion in the intestine. Functions of Bile Bile acids brings about the absorption of fat and fat soluble vitamins like

Cholesterol significance in animals Cholesterol belong to the group of steroid present in animal fat. About 10% of the bile is the cholesterol, secreted by hepatic cells. There are two principle sources of  cholesterol in the bile- Synthesized by the hepatic cells By absorption from the intestine through portal circulation to the liver  Gall stones and their formation

Bile pigments and Jaundice Bile pigments The bile pigments are the waste products of the hemoglobin (Hb) breakdown give yellow/green colour to bile. Bilirubin, the brownish yellow pigment is readily oxidized into biliverdin which gives green colour to the bile of the herbivores. Bilirubin is produced from Hb with destruction of RBC in the reticuloendothelial system (RES)

Bile salts and Enterohepatic circulation Bile Salts Bile salts are Na or K salts of glycocholic and tauro cholic acids formed in the liver and found in the bile. In carnivores, man, sheep, goat and birds, tauro cholic acid predominate.  In pig and rabbit , it is the glyco cholic acid predominates.  Glycocholic acid is a

Functional anatomy of biliary secretion The basic functional unit of the liver is the liver lobule, which is constructed around a central vein. The lobule is composed of many hepatic cellular plates that radiate away from the central vein. Between the cells in the hepatic plates is the bile canaliculi that collect the bile secreted by

Physical properties of bile Bile from hepatic duct is a viscid, greenish or greenish yellow with golden tinge liquid with a bitter taste. the compositions varies upon whether the bile is obtained from gall bladder or from the ducts of the liver.  The constituents of the bile are Bile pigments Bile acids or salts of