Absorption and excretion in birds Absorption in birds Absorption of glucose occurs via both passive and carrier mediated transport system. Passive transport appears to predominate in the duodenum and jejunum. Chicken has a sodium dependent carrier system for the active transport of sugars. Carrier medicated transport of D -glucose is facilitated by a Na+-glucose co-transpoter protein. Amino

Avian Digestion in small and large intestine Small intestine Small intestine begins at the exit from the gizzard and ends at the junction of the small intestine, caeca and colon. It is relatively long and has a constant diameter. Of the three parts of the small intestine duodenum, jejunum and ileum, only the duodenum can be easily

Enzymatic digestion in birds After ingestion, the food is mixed with saliva and mucous to moisten the food.  Amylase, is produced by the salivary and oesophageal glands. The secretions of the proventriculus or glandular stomach are hydrochloric acid, pepsin that acts on protein and the hormone gastrin that stimulates the production and release of gastric juice in

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