1. ANIMAL PHYSIOLOGY: monogastric digestive tract
By: Eko Widodo
ENTER

2. Pre-test
1. Write an assay of not less than 300 words on what you know and understand about monogastric digestive physiology (in10 minutes)

3.  DIGESTIVE SYSTEM + Tonge Teath Salivary gland Liver pancreas
ALIMENTARY ORGANS
assesorY ORGANS +
mouth
FEED
pharinx
Up-take
Responsibility
oesophagus
digestion
stomach
Small intestines
absorption
Large intestines
cloaca
Mouth ~> cloaca

4. Animals
Capacity (l)
Stomach
Small intestine
Cecum
Colon rectum
Dogs 63 23 1 13
Pigs 29 33 6 32
Horse 9 30 16 45
Cattle 71 18 3 8
Sheep & Goat 67 21 2 10

5. anatomy

7. the physiology of digestion and nutrition, including:
anatomical views and digestive parts identification
the process of digestion and absorption
factors affecting digestibility of feeds

8. 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 the foodstuffs
The process of absorption includes:
Transport of the digested foods across the intestinal mucosa to the blood or lymph system

9. The General Mechanical Process:
Mastication - chewing
Deglutition - swallowing
Regurgitation - movement of digesta in reverse order from the stomach to mouth
Defecation - voiding the fecal, or waste, materials from the body

10. Animal Diet Types:
Species may be divided into dietary preference groups:
Herbivores consume plant materials, examples are horses and cattle
Carnivores consume flesh of other animals, examples are dogs and cats
Omnivores consume both plants and flesh, examples include the primates

11. Differing Digestive Tracts:
Farm animal species have a variety of digestive systems
Ruminants have four distinct stomach areas
examples include bovine, ovine and caprine
Nonruminants (also termed monogastrics) display considerable variety
hogs, dogs, and cats have a single, simple stomach
poultry have a two part stomach
horses have a large, functional cecum

12. Nonruminant Digestive System:
Mouth - prehension and chewing of food; some carbohydrate enzyme activity
Esophagus - route of food from mouth to stomach
Stomach - addition of hydrochloric acid and protein digesting enzymes, mixing and holding

13. Nonruminant Digestive System:
Small intestine - primary site of digestion and absorption
Large intestine - major site of water absorption and preparation of digesta for excretion

14. Nonruminant Variations:
Poultry
Mouth: no teeth for chewing
Esophagus: a “crop” is contained within the esophagus for food holding and moistening
Stomach: divided into proventriculus (glandular area) and ventriculus (crushing area)
small intestine: primary site for enzymatic digestion
Large intestine: short and exiting into the cloaca; two large ceca with limited function

15. Nonruminant Variations:
Horse
Large intestine differences:
cecum is very large (may contain 50% of digesta)
cecum provides some nutrients to the horse via microbial fermentation

16. Ruminant Digestive System:
Many parts of the tract are similar to nonruminant monogastric description
Significant differences include:
Mouth contains no upper incisors
Stomach is divided into four major parts
rumen
reticulum
omasum
abomasum

17. Ruminant Digestive System:
Rumen
Largest digestive area of the compound stomach
Majority of fermentation of feedstuffs occurs here
Majority of absorption of byproducts of fermentation - volatile fatty acids or “VFA’s”

18. Ruminant Digestive System:
Reticulum
Receives feed from esophagus
Initiates mixing, regurgitation, and eructation
Environment for fermentation of feedstuffs

19. Ruminant Digestive System:
Omasum
Third area of the stomach receives the digesta outflow of the rumen/reticulum
Some water absorption and further subdivision of feed particles may occur

20. Ruminant Digestive System:
Abomasum
The fourth and final stomach compartment, but very similar in function to the pig stomach
Acid and enzyme stomach
Final holding and mixing area before the small intestine

21. Ruminant Digestive System:
Selected terms:
Regurgitation - controlled reverse movement of coarse feedstuffs from reticulum/rumen via esophagus to mouth for rechewing
Eructation - expulsion of accumulated fermentation gases from rumen via esophagus
Rumination - refers to the processing of feedstuffs in the reticulum/rumen, to include fermentation, regurgitation, eructation

22. Chemistry of Digestion:
Digestion involves enzymes and acids produced by the host animal or microbes working in symbiosis with the host
Enzymes break specific chemical bonds in feeds
Domestic animals produce enzymes to digest nonfibrous carbohydrates, fats, and proteins
Only microbes have enzyme systems to digest fibrous carbohydrates, such as cellulose

23. Digestion of Carbohydrates:
General carbohydrate digesting enzyme (amylase) in the mouth begins digestion; little amylase is found in horses and none in ruminants
Carbohydrate digesting enzymes (amylase) from the pancreas, and intestinal mucosa (sucrase, maltase, lactase) complete carbohydrate digestion

24. Digestion of Proteins:
Protein digesting enzyme (pepsin) and hydrochloric acid in the stomach begin significant digestion
Protein digesting enzymes (e.g. trypsin) from the pancreas and intestinal mucosa complete digestion in the small intestine
Young nursing animals – rennin coagulates milk allowing more complete digestion

25. Digestion of Fat:
Fat digesting enzyme (lipase) in the stomach begins digestion
Fat digesting enzymes from the pancreas (lipase) and intestinal mucosa complete digestion in the small intestine
To assist in fat digestion, bile from the liver emulsifies fat into smaller droplets in the small intestine

26. Factors Affecting Digestibility:
Rate of passage - in general, increased rate of passage of digesta through the tract reduces digestibility, factors increasing rate of passage include:
Increased level of feeding/intake (ruminants)
Finer processing (such as grinding) of feed
Note: grinding grain usually increases digestibility but grinding hay decreases digestibility

27. stomach
Divided into cardia (entrance), fundus (body) and pylorus (termination)

28. Cardiac gland region
This is not necessarily in the cardia which is usually non glandular. This mucosa contains glands which produce mucus.
Fundic gland region
Fundic glands are simple and tubular and contain 3 types of cells:
Mucus neck cells, which produce mucus
Parietal cells, which produce HCl
Peptic or zymogen cells, which produce enzymes

29. Pyloric gland region
These glands are lined entirely with mucus-secreting cells like those within the cardiac glands. The hormone gastrin is produced by G cells of the pyloric gland.
Gastric juice
Is the total secretory product (fluid) from the surface epithelial cells and the cardiac, fundic and pyloric glands of the stomach. It is colourless and is made up of two components; a parietal cell acid component, and an alkaline component containing pepsin, mucin and electrolytes.

30. Pepsin
Is synthesised in the peptic cells from the inactive precursor, pepsinogen. It begins the digestion of protein in the stomach if the pH is acid. Proteins are converted to proteoses and peptones in the stomach, and digestion of protein Is completed in the intestine.

31. Rennin
Is a milk clotting enzyme secreted as inactive prorennin which Is activated by the presence of acid. In adition to clotting milk rennin also exhibits proteolytic properties. It is foundin the gastric juices of calves, lambs, and young pigs.

32. Gastic lipase
Is present in low concentration in the gastric juice of carnivores. It can hydrolyse fats that are emulsified, such as milk fat but probably had little effect on unemulsified fats.

33. Hydrochloric acid
Is produced by the parietal cells of the fundic glands of the stomach of all vetebrates. HCl activates pepsin and rennin and aids pepsin in protein digestion by lowering the pH of the stomach contents.

34. Phases of gastric juice secretion
Cephalic phase
Presence of food in the mouth may result in the secretion of gastric juice in the stomach.
Gastric phase
When food reaches the stomach, gastric juice secretion Increases for a period up to several hours.

35. Intestinal phase
When products of gastric digestion reach the duodenum, intestinal gastrin is produced.

36. Pancreas and pancreatic secretion
The pancreas consists of exocrine and endocrine portions. The exocrine part consists of acini responsible for the production of pancreatic juice and ducts which convey the juice to the duodenum. The endocrine portion is made up of the Islets of langerhans which secrete insulin into the bloodstream.

37. Pancreatic juice is secreted under the influence of two hormones produced In the mucosa of the duodenum.
Secretin increases the rate of flow and hydrocarbonate concentration of the pancreatic juice.
Pancreozymin increases the amount of enzymes In the pancreatic juice. An additional factor which results in a pancreatic juice rich in enzymes Is neurogenic stimulation by the vagus nerve.

38. Pancreatic juice contains sodium carbonate, which neutralises acid from the stomach and Increases alkalinity of intestinal fluid, and a number of enzymes for the hydrolisis of proteins, fats and carbohydrates.

39. There are 3 major group of enzymes In pancreatic juice.
Pancreatic proteases or proteolitic enzymes in the pancreas are trypsin, chymotrypsin A, chymotrypsin B, and the carboxypeptidases.
Pancreatic amylase is an αamylase, probably structurally identical to salivary amylase secreted in an active state. Amylase attacks starch grains and produces dextrins and maltose. Maltase is also present in pancreatic juice and it hydrolyses maltose to glucose.

40. Pancreatic lipase is secreted in an active form and it hydrolyses fats into carboxylic (fatty) acids and glycerol. Pancreatic lipase is most effective after the fats have been emulsified by bile.
Bile is a greenish yellow liquid consisting largely of water, bile salts, bile pigments and cholesterol with smaller amount of fats and inorganic salts.

41. Intestinal secretion
Intestinal juice, called succus entericus, is produced by the intestinal glands scattered throughout the entire small intestine, and submucosal duodenal glands. Secretion of these glands is stimulated by the presence of food in the intestine. The release of intestinal juice Is also brought about by hormone called enterocrinin.

42. In addition to water, salts and mucus, a number of enzymes have been described In the intestinal juice. These include enterokinase (which activates trypsinogen), and the following inverting enzymes:
Maltase - hydrolyses maltose to glucose
Sucrase - sucrose to glucose and levulose
Lactase - lactose to glucose and galactose
Peptidase - peptides to amino acids
Polynucleotidase - splits nucleic acids into mononucleotides
Nucleotidase - nucleotide into nucleosides and phosphoric acid
Nucleosidase - hydrolyses nucleosides

44. prehension deglutition
The manner in which food is grasped. Picked up, carried to the mouth, mixed with saliva and manipulated before swallowing
deglutition
The process in which food particles are swallowed whole and pass to the crop

45. Passage of ingesta through the tract
Rate
The rate of feed passage through the alimentary canal is influenced by the consistency, hardness and water content of the feed and by the amount consumed.

46. Factors Affecting Digestibility:
Rate of passage - in general, increased rate of passage of digesta through the tract reduces digestibility, factors increasing rate of passage include:
Increased level of feeding/intake (ruminants)
Finer processing (such as grinding) of feed
Note: grinding grain usually increases digestibility but grinding hay decreases digestibility

47. Motility
Crop and esophagus
Proventriculus
Gizzard
Small intestine
Large intestine

48. Thank you