Digestive System of Non-Ruminant animals.pptx

The digestive systems of animals and humans. Important to know.

1. Biochemistry of Digestion and Absorption of Feedstuffs in Non-Ruminants

2. Outline Digestion and Absorption Non-Ruminant digestion and Absorption parts and Functions Non –Ruminant Carbohydrate Digestion Absorption of Nutrients-CHO Digestion of Proteins Absorption of protein Lipid Digestion Absorption of Lipid Summary

3. Digestion and Absorption The process of digestion includes: –The prehension of food or feed –The mechanical chewing and grinding –Mixing with digestive acids and enzymes to chemically break down feedstuffs The process of absorption includes: –Transport of the digested foods across the intestinal mucosa to the blood or lymph system

4. Non-Ruminant Simple digestive system - Monogastric -Feed must be highly quality concentrates -Cannot digest large amounts of fiber Some examples are: Human Dogs Cats Pigs Poultry

5. Non-ruminant digestive system Mouth Esophagus Stomach - Enzymes acts on feed -Churns and mixes Small intestine Large intestine Accessory System -Liver ( produces bile that acts on fat) -Pancreas(produces insulin) Anus -End of the digestive tract

6. Non –Ruminant Carbohydrate Digestion Mouth : initial opening of alimentary canal Salivary Glands secrete juices that contain enzymes to help break up the food Mastication chewing, crushing, preparing food for swallowing Mouth Salivary amylase

7. Stomach Stomach is extremely elastic bag Acid and pepsin to unfold proteins Extensive microbial populations to breakdown anaerobically ferment feed. Stomach

8. Continued…. Pancreas Pancreatic amylase Hydrolyzes alpha 1-4 linkages Produces mono- saccharides , disaccharides and polysaccharides Major importance in hydrolyzing starch and glycogen to maltose Amylase Polysaccharides Disaccharides

9. Digestion in Small Intestine Digestion mediated by enzymes synthesized by cells lining the small intestine (brush border) Brush Border Enzymes Disaccharides Mono- saccharides Exception is β -1,4 bonds in cellulose

10. Digestion in Small Intestine Sucrose Glucose + Fructose Ruminants do not have sucrase Maltase Maltose Glucose + Glucose Lactase Lactose Glucose + Galactose Sucrase

11. Digestion in Large Intestine Large Intestine 3 Sections – cecum –colon –rectum •Active in water reabsorption •Secretion of some minerals •*Bacterial Fermentation*

12. Overview of CHO Digestion Location Enzymes Form of Dietary CHO Mouth Salivary Amylase Starch Maltose Sucrose Lactose Stomach (amylase from saliva) Dextrin → Maltose Small Intestine Pancreatic Amylase Maltose Brush Border Enzymes Glucose Fructose Galactose + + + Glucose Glucose Glucose Large Intestine None Bacterial Micro-flora Ferment Cellulose

13. Nutrient Absorption – CH0 Active transport for glucose and galactose Glucose and Galactose enter epithelial cells via - Sodium-linked secondary active transport across the apical membrane. Facilitated transport for Fructose The sugars exit the cells across the basolateral membrane by facilitated diffusion

14. Villi in the small intestine All the nutrients including carbohydrates must be come in contact with villi of small intestine to be absorbed. Munna

15. Carbohydrates uptake by small intestine Monosaccharides are mainly absorbed by the small intestine. Munna

16. Absorption Villi-expand absorptive surface Most nutrients absorbed here Nutrients move from the villi to the blood to be transported all over the body Absorption in Small Intestines

17. Absorption in Small Intestines Mechanism of Absorption Pores; carriers; pumps; pinocytosis (“drinking in”) Not just a process of diffusion Active “shuttle” transport Pores are selective Carriers are specific Takes energy (kcal) for digestion Dietary induced thermo genesis

18. Carbohydrates from small intestine to liver The absorption of monosaccharides from the small intestine to the liver via the portal vein is an essential step in our digestive process . The portal vein is a blood vessel that carries blood from the abdomen to the liver.  The capillaries in the small intestine join to the portal vein, which transports mono saccharides directly to the liver. Munna

19. Selective carbohydrates absorption by liver L iver doesn't actively absorb nutrients like monosaccharides from the bloodstream. Instead, it selectively takes up nutrients, including monosaccharides, from the blood through specific transporters located on its cell membranes (hepatocytes). Munna

20. Carbohydrates absorption in large intestine Almost all of the carbohydrates (95%), except for dietary fiber and resistant starches, are efficiently digested and absorbed into the small intestine. Some of the remaining indigestible carbohydrates are broken down by enzymes released by bacteria in the large intestine . While the large intestine contributes a smaller percentage in absorption,  the Short Chain F atty A cids (SCFAs) it produces offer various health benefits, including promoting gut health and potentially protecting against certain diseases . Munna

21. Continued… Limited absorption:  Only a small amount of indigestible carbohydrates and resistant starches reach the large intestine. Types of carbohydrates absorbed:  Short-chain fatty acids (SCFAs) produced by gut bacteria fermenting these remaining carbohydrates are the main source of energy absorbed. Mechanisms of absorption:  SCFAs are directly absorbed into the epithelial cells of the colon and enter the bloodstream . Munna

22. Absorption from Large Intestines Site of water, salt, vitamin absorption (leaving a mass in a semi-solid state) Almost everything of nutritional value has been utilized by time it reaches the large intestines -- leaving only waste Feces contains some water, dead intestinal cells, bacteria, non-absorbed remains of digestion Helpful bacteria in the large intestine feed on the “leftovers” and make vitamins like vitamin K and B.

23. Digestion of proteins The protein load received by the gut is derived from two primary sources: 70-100 g dietary protein, and 35-200 g endogenous protein The latter either as secreted enzymes and proteins in the gut or from intestinal epithelial cell turnover In healthy adults, only 1-2 g nitrogen, equivalent to 6-12g protein, are lost in the feces on a daily basis Thus, the digestion and absorption of protein is extremely efficient

24. Digestion of proteins The digestion of proteins begins in the stomach, which secretes gastric juice, a unique solution containing hydrochloric acid and the pro-enzyme pep- sinogen : Hydrochloric acid: Stomach acid is too dilute (pH 2-3) to hydrolyze proteins; however, the acid functions to kill some bacteria and to denature proteins, making them more susceptible to subsequent hydrolysis by proteases

25. Continued…. Pepsin: This acid-stable endopeptidase is secreted by the serous cells of the stomach as an inactive zymogen (or pro-enzyme), pep- sinogen . Digestion of proteins by pancreatic enzymes On entering the small intestine, large polypeptides produced in the stomach by the action of pepsin are further cleaved to oligopeptides and amino acids by a group of pancreatic proteases These enzymes, like pepsin, are synthesized and secreted as inactive zymogens

26. Overview of protein digestion

27. Absorption of Protein Amino acids enter the absorptive epithelial cells via sodium-linked secondary active transport across the apical membrane . Amino acids are then transported across the basolateral membrane by facilitated diffusion

28. Absorption of Amino Acids Amino acids are absorbed from the lumen of the small intestine principally by semi-specific Na + -dependent transport proteins in the luminal membrane of the intestinal cell brush border, similar to that already seen for carbohydrate transport. Munna

29. Lipid Digestion Fat breakdown about 50 % of energy in liver, kidney and skeletal muscles up to 95 % of energy cardiac muscle Fats are the major source of energy for fasting animal organism in diabetes Digestion – Mainly occur in small intestine. Enzyme – pancreatic lipase . Lipase catalyzes hydrolysis at the C1 and C3 positions of TGs producing free fatty acids and 2-monoacylglycerol .

30. DIGESTION OF DIETARY LIPIDS

31. Lipid Digestion: Sites and Enzymes Sites : The stomach The small intestine Enzymes: 1. Act in stomach: Mouth: Lingual lipase Stomach: Gastric lipase 2. Act in small intestine: Pancreatic enzymes Lipase and co-lipase Cholesterol esterase Phospholipase A2 Lysophospholipase

32. Hormonal control of digestion in small intestine The digestion in small intestine is hormonally controlled. Two small peptide hormones are released from cells of the upper part of small intestine: Cholecystokinin (CCK) Secretin

33. Hormonal control of digestion in small intestine Cholecystokinin (CCK): Secretion of pancreatic enzymes Bile secretion Slow release of gastric contents Secretin : Release of watery solution Rich in bicarbonate by pancreas

34. Fatty acids and monoglycerides enter the enterocytes by simple diffusion. Inside the enterocytes the molecules are reassembled into triglycerides and are packaged into large particles called chylomicrons. The chylomicrons are secreted across the basolateral membrane by exocytosis. The chylomicrons enter the lymphatic capillaries. The flow of lymphatic fluid carries the chylomicrons to the bloodstream Absorption of Lipid

35. Continued… Lipids within the digestive system will tend to hydrophobically aggregate to form large fat globules. Bile salts, secreted from the gall bladder, emulsify these fat globules and break them up into smaller droplets. Hydrolytic enzymes called lipases then digest the fats into their component parts. When the fatty acids are absorbed into the epithelial cells of the intestinal lining, they are combined to form triglycerides. The triglycerides are combined with proteins inside the Golgi apparatus to form chylomicrons. Munna

36. Continued… Munna

37. Absorption of vitamins Vitamins are organic molecules necessary for normal metabolism in animals, but either are not synthesized in the body or are synthesized in inadequate quantities and must be obtained from the diet. Essentially all vitamin absorption occurs in the small intestine . Most water soluble vitamins are available for intestinal absorption from two sources: the diet, and synthesis by microbes in the large intestine or, in the case of ruminants, the  rumen. Munna

38. Continued.… The fat soluble vitamins A, D, E and K are absorbed from the intestinal lumen using the same mechanisms used for absorption of other lipids. In short, they are incorporated into mixed micelles with other lipids and bile acids in the lumen of the small intestine and enter the enterocyte largely by diffusion. Within the enterocyte , they are incorporated into chylomicrons and exported via exocytosis into lymph. Munna

39. Absorption of Minerals Mineral absorption is normally proportional to dietary intake The vast bulk of mineral absorption occurs in the small intestine . Minerals are clearly required for health, but most also are quite toxic when present at higher than normal concentrations. The small intestine, with its villi and intricate epithelial cell lining, serves as the main stage for mineral absorption. Each mineral has its own unique entrance strategy, a testament to the exquisite adaptability of the bodies. Munna

40. Continued.… Munna

41. Absorption of Water The specific mechanisms animals use to absorb water differ depending on their physiology and environment: Intestinal absorption:  Similar to humans, many animals absorb water through their intestines. The small intestine in particular is equipped with specialized cells and transporters that facilitate water uptake. Skin absorption:  Amphibians like frogs and toads are masters of skin absorption, drawing water directly through their permeable skin. Some reptiles also utilize skin absorption to a lesser extent . Munna

42. Cloacal reabsorption :   Birds excrete a concentrated form of urine and feces combined, called a cloaca. In many birds, the cloaca reabsorbs water from this waste before expulsion, maximizing water conservation. Continued.… Munna

43. Summary of Digestion & Absorption in Non-Ruminant Consists of starches , glycogen, sucrase , lactose , glucose , fructose Polysaccharides broken down to mono- saccharides Mono- saccharides taken up by active transport or facilitated diffusion and carried to liver. Glucose is transported to cells requiring energy. Dietary lipids are relatively hydrophobic Lipid digestion begins in stomach Emulsification of lipids occurs in duodenum, helped by peristalsis and bile salts

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