Digestive Physiology. For: ADVS 1110 Introduction to Animal Science

Transcription

1 Digestive Physiology For: ADVS 1110 Introduction to Animal Science

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3 Digestion Digestive Systems Simple Monogastric Systems: Animal Humans Monkey Pig Dog Poultry Food Class Omnivore Omnivore Omnivore Carnivore Omnivore

4 Digestion Digestive Systems Polygastric Systems: Animal Cow Sheep Goat Food Class Herbivore Herbivore Herbivore

5 Digestion Digestive Systems Monogastric Functional Cecal Systems: Animal Horse Rabbit Guinea Pig Hamster Rat Mouse Food Class Herbivore Herbivore Herbivore Omnivore Omnivore Omnivore

6 Digestion GI Tract FUNCTIONS OF THE GI TRACT: Movement of food. Secretion of digestive juices. Absorption of the digested food, water and electrolytes. Esophagus allows for the simple passage of food from one point to another. Storage of food in the body of the stomach, or fecal matter in the descending colon. Digestion of food in the stomach, duodenum, jejunum and ileum. Absorption of the digestive-end-products (deps) in the entire small intestine and proximal half of the colon (large).

7 Digestion GI Tract Amount of ingested food determined by: 1. Hunger the intrinsic desire for food, regardless of food type or preference. 2. Appetite the specific type of food that is preferentially sought.

8 Digestion GI Tract The mechanical aspects of food ingestion: Mastication includes chewing as well as ingestion. Incisors cutting and food intake 55 psi. Molars grinding 200 psi. Swallowing also referred to as deglutition.

9 Digestion GI Tract DENTITION: Temporary & Permanent Dentition: Horses Cattle Sheep Pig Dog Cat

10 Digestion GI Tract DENTITION/TEETH: (front to back) Incisors = I* Canines = C* Premolars = P Molars = M * Usually absent in the mare.

11 Digestion GI Tract DENTITION SECTION THROUGH A MOLAR TOOTH:

12 Digestion GI Tract TWO TYPES OF MOVEMENT IN THE GI TRACT: 1. Mixing Movements which keep the intestinal contents thoroughly mixed at all times. 2. Propulsive Movements which cause the food to move forward along the tract at an appropriate rate for digestion and absorption.

13 Digestion GI Tract OTHER TYPES OF MOVEMENTS: Peristalsis basic propulsive movement. Peristalsis is the rhythmic contractions and movements by which the GI tract propels it s contents. Distension is the usual stimulus for peristalsis. Analward Peristaltic Movements peristalsis can occur in either direction, from a stimulated point, but normally dies out rapidly in the oral direction. Gradient Theory is that there are more frequent neural impluses (peristaltic) analward than in the oral direction. Example: 11 contractions/minute vs 6-7 contractions/minute.

14 Digestion GI Tract THE HERBIVORE GI TRACT DESCENDING ORDER: 1. Oral Cavity 8. Abomasum (True Stomach) 2. Incisors 9. Small Intestine: a. Duodenum; b. Jejunum; c. Illeum 3. Molars 10. Cecum 4. Esophagus 11. Large Intestine (Colon): a. Ascending, b. Descending 5. Rumen (Paunch) 12. Rectum 6. Reticulum (Hardware Stomach; Honeycomb; Tripe) 7. Omasum (Manyplies) 13. Anus

15 Beef Cattle GI Tract

16 Digestion GI Tract Terminology: Food As It Moves Through The Digestive System 1. Feed or Feedstuff. 2. Ingesta after swallowing. 3. Cud after leaving rumen. 4. Chyme after leaving the true stomach or only stomach. 5. Digestive End Products (DEPs) those nutrient ingredients absorbed after digestion. 6. Fecal Material or Non-Digested End Products lower end of large intestine or large colon. 7. Feces waste matter removed from the rectum after all digestive processes, and deposited outside the body.

17 Digestion GI Tract The ruminant system is large in relation to the size of the animal. It s four (4) compartments are bunched and joined together to form a compact structure.

18 Digestion The most important products of the rumen fermentation vat process as illustrated in a diagrammatic form, are the Volatile Fatty Acids (VFA s) VFA s represent the major source of energy derived from the feed in a usable form.

19 Digestion GI Tract In the digestive process most feed materials follow pathways indicated by arrows. The rumen, consisting of several different regions, is much larger than the three (3) other compartments combined.

20 Digestion GI Tract The possible routes of feed in ruminants:

21 Digestion GI Tract The stomach of a monogastric animal is much smaller than that of the ruminant stomach in relation to the size of the animal and other parts of the digestive tract:

22 Digestion GI Tract Approximate relative capacity of ruminant stomach compartments: Compartment At Birth At 4 Months (%) At Maturity (%) (%) Rumen Reticulum Omasum Abomasum Total

23 Digestion GI Tract In contrast with the ruminant system, the stomach of monogastric animals has only one principal digestive cavity, including one (1) non-glandular and three (3) glandular regions:

24 Digestion GI Tract Digestive System of the Horse:

25 Digestion - Avian Digestive Tract of the Chicken:

26 Digestion GI Tract The Cecum in Various Animal Species:

27 Digestion GI Tract Digestive tract sizes and capacities of mature ruminant animals: Species Part of Digestive Tract Stomach Cow Ewe Rumen 40 gal 5 gal Reticulum 2 gal 2 qt Omasum 4 gal 1 qt Abomasum 4 gal 3 qt Small Intestine 15 gal (130 ft) 2 gal (80 ft) Large Intestine 10 gal 6 qt

28 Digestion GI Tract Comparative capacities of monogastric (simple stomach) animals: Part of Digestive Tract Horse Pig Man Stomach 20 qts 8 qts 1 qt Small Intestine 48 qts 8 qts 2 qts Large Intestine 120 qts (cecum also) 8 qts 2 qts

29 Digestion GI Tract - Summary The Digestive Pathway in Monogastrics: Mouth Esophagus Simple Stomach Small Intestine (duodenum, jejunum, ileum) Cecum Large Intestine Rectum Anus

30 Digestion GI Tract - Summary The Digestive Pathway in Poultry: Mouth Esophagus Crop Esophagus (stomach) Proventriculus Gizzard Small Intestine (duodenum, jejunum, ileum) Ceca Large Intestine Cloaca Vent

31 Digestion GI Tract - Summary The Digestive Pathway in Ruminants: Mouth Esophagus Reticulo-rumen Regurgitated, Rechewed, reinsalivated, reswallowed Reticulo-rumen Omasum Abomasum Small Intestine (duodenum, jejunum, ileum) Cecum Large Intestine Rectum Anus

32 Digestion Circulation of Blood in Mammals:

33 Annual Manure Production of Animals: Species Animal Weight (lb.) Total Manure Production (tons/yr) Dairy Cattle 1, Beef Cow 1, Beef Feeder Swine Sheep , Poultry Broiler Horses

34 Digestion - GI Tract The Human Alimentary Canal (GI Tract):

35 Digestion - Avian

36 Digestion - Avian Mouth no teeth; therefore coarse feed must move to gizzard. Fowl break their feed into a size that can be swallowed by pecking with their beaks or by scratching with their feet. Crop is an esophageal diverticulum and serves as a storage area for recently digested food. Proventriculus is similar to the stomach in carnivorous animals. Gizzard primary function is the reduction of the size of food particles by a grinding action. Pepsin is present, an acid-base activity takes place, along with meager proteolysis.

37 Digestion - Avian Small Intestine digestive activity here is similar as in mammals. Enzymes of the pancreas and the brush border aid in digestive activity. Monosaccharides and amino acids are carried by active transport through the gut wall. Fat absorption takes place in lower half of small intestine and enhanced by the presence of bile. Ceca most of the fiber digestion takes place here via fermentation. Large Intestine concerned with water absorption. Cloaca chamber into which the urinary and genital tracts also open into.

38 Digestion A diagram of a cross-section of the intestinal tract showing it s tissue layers:

39 Digestion - Ruminant

40 Digestion of Feed Nutrients - Ruminants

41 Digestion - Ruminant Routes of carbohydrate utilization in ruminants:

42 Digestion - Non-Ruminant

43 Digestion of Feed Nutrients Non- Ruminants

44 Digestion Non-Ruminant Routes of carbohydrate utilization in nonruminants:

45 Digestion Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Mouth Saliva Ptyalin Starch > Maltose Stomach Gastric Pepsin Proteins > Peptones > Proteoses Stomach Gastric Rennin Casein > Paracasein Stomach Gastric Lipase Fats > Higher Fatty Acids, Glycerol

46 Digestion Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Pancreas Pancreatic Trypsin Proteins > Proteoses & Peptones, Peptides > Amino Acids Pancreas Pancreatic Amylase Starch > Maltose > Glucose Pancreas Pancreatic Steapsin (Lipase) Fats > Higher Fatty Acids & Glycerol

47 Digestion Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Liver Bile Bile Emulsification of fats (Liquid) Small Intestine Intestinal Juices Erepsin Peptides > Amino Acids Small Intestine Intestinal Juices Invertases (Sugar Enzymes)

48 Digestion Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Small Intestine Intestinal Juices Invertases (Sugar Enzymes) Maltase Maltose > 2 Glucose Sucrase Sucrose > Glucose & Fructose Lactase Lactose > Glucose & Galactose

49 Digestion - Monosaccharides The more common carbohydrates, sources and functions: This is an abbreviated table and provides only a partial list of the carbohydrates (CHO s); but includes the important animal science ones. Name Sources Functions Pentoses (5-carbon) Monosaccharides Not as common Hexoses (6-carbon ) Glucose Corn syrup, fruit Principal blood sugar Fructose Fruit, honey Converted to glucose Galactose One of the two molecules in milk Converted to glucose

50 Digestion - Disaccharides The more common carbohydrates, sources and functions: Name Sources Functions Disaccharides Lactose Milk Yields glucose and galactose in digestion Maltose Germinating seeds Yields two (2) units of glucose in digestion Sucrose Cane & Sugar Beets Yields glucose and fructose in digestion

51 Digestion - Polysaccharides The more common carbohydrates, sources and functions: Name Sources Functions Pentosans Polysaccharides Hexosans Starch Seeds, tubers Principal energy source for monogastrics Cellulose Glycogen Plant leaves & stems (cell walls) Limited supply in animal tissues Major source of energy for ruminants; requires microbial enzyme cellulase Reserve form of glucose in muscles and liver

52 Digestion The Liver is vital to digestion, filtering and absorption of nutrients Liver Function: Produces exocrine secretion named bile. Bile is stored in the gall bladder until it is required for digestive purposes. Synthetic Reactions: Synthesis of certain amino acids, plasma proteins, prothrombin, antibodies, urea, creatine, cholesterol. Glycogen and glucose (gluconeogenesis). Phospholipids ( for cell membranes). Fatty acids. Ketone bodies.

53 Digestion Liver Function: (continued) Metabolic Reactions: Breakdown of glucose, glycogen, fatty acids, glycerol, amino acids Metabolism of hormones (insulin, aldosterone, testerone, estrogens, and thyroid hormone). Inter-conversion of certain amino acids to simple sugars and vice-versa. Adenine Tri-Phosphate formation. (ATP) Embryonic formation of blood cells. Destruction of aged blood cells.

54 Digestion Liver Function: (continued) Storage: Glycogen Amino acids Fats Vitamins (A, B complex, D and E) Iron and Copper. Detoxification Conversion of toxic substances to harmless compounds.

55 Digestion Hormones Other Than Those of the Pituitary: Hormone Source Primary Function Thyroxin Thyroid Growth, metabolic rate Thyrocalcitonin Thyroid Lowers blood calcium and phosphate Parathyroidhormone Parathyroid Elevates blood calcium, lowers blood phosphate Epinephrine Adrenal Medulla Mobilization of glycogen, increased blood flow

56 Digestion Hormones Other Than Those of the Pituitary: Hormone Source Primary Function Insulin Pancreas Lowers blood glucose, increase utilization of glucose, and synthesis of protein and fat, decreases glucogenesis Glucocorticoids (Cortisol, Corticosterone) Mineral Corticoids (Aldosterone) Adrenal Cortex Adrenal Cortex Promotes synthesis of carbohydrates; protein breakdown Sodium retention and potassium loss through kidney

57 Digestion Hormones Important in Gastro-Intestinal Function: Hormone Origin Releasing Mechanism Gastrin Pylorus Distension and movement of stomach Function Stimulation of acid secretion by gastric glands Entero-gastrone Duodenum Fat and fatty acids + bile in duodenum Secretin Duodenum Acids and peptones in duodenum Inhibition of gastric secretion and motility Stimulation of pancreatic secretion (water & electrolytes)

58 Digestion Hormones Important in Gastro-Intestinal Function: Hormone Origin Releasing Mechanism Pancreozymin Duodenum Acids and peptones in duodenum Function Stimulation of pancreas secretion (enzymes) Chole-cystokinin Duodenum Fat in duodenum Contraction of gall bladder and relaxation of the sphincter of oddi Enterocrinin Jejunum Food digestion products Simulation of intestinal secretions: 1) sucrase; 2) maltase; 3) lactase; & 4) Intestinal lipase

59 Digestion - Blood Distribution of total blood volume in different portions of the cardiovascular system: Part of Cardiovascular System Percent of Total (%) Arterioles & Capillaries 7 Heart 9 Arteries 11 Pulmonary Circulation 12 Veins & Venules 61

60 Digestion - Blood Components of blood: Plasma: Liquid portion of blood Straw colored 55-57% of blood volume Water Electrolytes (Na +, K +, Ca ++, Cl -, HCD 3-, PO 4 ) Carbohydrates (Glucose) Lipids Vitamins Urea CO 2 (Gases from lungs or tissue) O 2

61 Digestion - Blood Components of blood: (continued) Proteins (Mostly manufactured from liver, some from cell disintegration) Important All of the prior components, Plasma and Proteins are absorbed from the gut. Formed Elements of blood: Erythrocytes RBC Leukocytes WBC Platelets: Non-nucleated Aids in clotting

62 Digestion - Blood Mammalian Heart in Longitudinal Section:

63 Digestion - Blood

64 Digestion

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