Digestive structures in birds In birds, alimentary canal is a long tube like organ starting from the beak at the head and ending with the vent or cloaca in the abdominal region. Special features of the avian digestive system includes presence of beak, Absence of teeth, Proventriculus, Gizzard, Paired caeca and Vent. Digestive structures in birds […]

Absorption of minerals, vitamins and water Absorption of minerals Sodium is transported as sodium co-transport along with glucose and amino acids and Sodium is also coupled transported with chloride ion Sodium ion also shows diffusion across the electrochemical gradient. Potassium is transported by passive diffusion across the concentration gradient Bicarbonate ions are transported actively or rarely with

Absorption of Carbohydrate, lipid and Protein Carbohydrate absorption Monosaccharides (eg. glucose, fructose) are absorbed by active transport mediated by carrier and sodium pump. Absorption of glucose Glucose gets attached to specific transport proteins that lie on the luminal side of the enterocytes. These transport proteins have two binding sites one for glucose and one for sodium. Once glucose and Na+ occupy

Absorption of digested food in animals Absorption of digested food in animals is the process whereby the products of digestion and the digested foodstuff form the lumen of the gut is transferred to the blood or the lymph across the epithelial cell membrane. Site of absorption No absorption of food or end products of digestion

Role of Large Intestine in digestion Large intestine of herbivores Large intestine is of great importance in herbivores. In simple stomached animals, the enormous caecum and colon are involved in the microbial fermentation hence they are called as hind gut digesters. The absorption of the fermented end products of cellulose and digestible products synthesised by bacteria

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