1. Digestive Systems

2. Digestive Systems Overviews
Objectives
Describe the structures and functions of the digestive system of ruminant animals
Draw the structures of the digestive system of ruminant animals
Label the structures of the digestive system of ruminant animals

3. Digestion
Digestion: Breaking down large, nutrient macromolecules into simpler molecules for use by an organism.
Food enters the mouth and goes through mechanical and chemical changes as it passes through the alimentary canal.

4. Types of Stomachs Simple Stomach Complex Stomach
Man, Pig
Complex Stomach
Cattle, Sheep, Goats
Simple Stomach with enlarged ceacum
Horses, Rabbits, Guinea Pigs

5. Parts of Digestive Tract
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

6. Parts of Digestive Tract
Pharynx: funnel shaped muscle between mouth and esophagus
part of digestive and respiratory tracts
Esophagus: muscular tube connecting pharnyx to stomach
muscle contractions move food down to stomach

7. Parts of Digestive Tract
Stomach: located between esophagus and small intestine
Two basics types
Simple
Ruminant

8. Parts of Digestive Tract
Simple Stomach
Humans, swine, rabbits and horses
Divided into three regions
cardiac
fundus
pylorus

9. Simple Stomach Digestion: is mechanical, muscle contractions
is chemical, enzymes soften and break down macromolecules of food
enzymes are catalysts, they start the chemical reactions

10. Simple Stomach Enzymes that break down food
Gastric-break down proteins in stomach
Liver and pancreatic-break down fats in small intestine
Intestinal-break down carbohydrates and proteins in small intestine

11. Parts of Digestion Tract
Ruminant Stomach
Sheep, Cows and Goats
Occupies 3/4 of the abdominal cavity

12. Four Components of Ruminant Stomach
Rumen
composes 80% of ruminant stomach in mature bovine animals and 30% in young animals
Reticulum
composes about 5% of bovine stomach
prevents indigestible objects from entering the stomach

13. Four Components of Ruminant Stomach
Omasum
composes 7-8% of bovine stomach
absorbs mostly water
Abomasum
the “true” stomach
composes 7-8% of stomach in mature animals and 70% in young animals

15. Digestion in the Ruminant Stomach
Rumination: The process of regurgitation, re-mastication, re-salivation and re-swallowing of food.
Purpose: To smash and break up food which provides more surface area bacteria to break down

16. Parts of Digestive Tract
Small Intestine: long, coiled tube connecting the stomach with the large intestine.
Is covered by villi which increases surface area to increase absorption
Food moves through by muscle contractions called peristaltic movement
Final breakdown and absorption of nutrients occurs here

17. Parts of the Digestive Tract
Large Intestine
Includes cecum, colon and rectum
Absorbs water
Very little nutrient absorption takes place here

18. Parts of the Digestive Tract
Accessory Organs
Pancreas
secretes enzymes which breakdown fat and starches
Liver
secrets bile which digest fats

19. The Digestion Process

20. The Digestion Process Food is broken down
Animals have digestive systems adapted to the foods that they consume
Four types of digestive systems
Ruminant(polygstric)
Simple Stomach(monogastric)
Avian
Equine-modified simple stomach

21. Ruminant Digestive System
Modified to handle the breakdown of large amounts of fiber

22. Ruminant Digestive System
Mouth
no upper incisors, hard palate
molars for grinding coarse vegetation
saliva does not contain enzymes
Esophagus
muscular tube connecting the mouth to the stomach

23. Ruminant Digestive Systems
The Four Compartmented Stomach
Rumen: storage area and fermentation vat
Reticulum: nails and wire may be found here-hardware stomach
Omasum: eliminates excess water from feed
Abomasum: true stomach, gastric juices and enzymes are secreted

24. Ruminant Digestive Systems
Stomach (cont.)
Regurgitation: first step in rumination
large quantities of roughage are consumed and are chewed just enough to swallow
after swallowing, regurgitation (“cud chewing”) takes place, food is re-chewed

25. Ruminant Digestive System
Small Intestine
connects stomach to large intestine
food nutrients absorbed into blood
contains bile and pancreatic juices
pushes food through by muscle contractions

26. Ruminant Digestive System
Large Intestine
Contains Cecum, Colon and Rectum
Cecum: sac at junction of small intestine and large intestine
Colon and rectum: at end of system
not as long as small intestine, but larger in diameter
water and some nutrient absorption occurs here
where residue solidifies before excretion

27. Monogastric Digestive System
Characterized by inability to digest roughage efficiently

28. Objectives
Describe the structures and functions of the digestive system of non-ruminant animas
Draw the structures of the digestive system of non-ruminant animals
Label the structure of the digestive system of non-ruminant animals

29. Monogastric Digestive System
Mouth
has upper and lower incisors
digestive enzymes secreted which breaks down nutrients
Esophagus
connects mouth to stomach

30. Monogastric Digestive System
Stomach
secretes Hydrochloric Acid to break down nutrients
enzymes such as pepsin also secreted here
churning action mixes food
small and large intestine
function just as in ruminant systems

32. Avian Digestive Systems
Characterized by several organs not found in other species that are adapted for grinding hard or encased food

33. Avian Digestive Systems
Mouth
no teeth which leads to the saying “scarce as a hen’s teeth!!”
Salivation excretion moistens food
Esophagus
has a modification called the “crop” which stores and moistens food
connects mouth and stomach

34. Avian Digestive Systems
Stomach
Contains two parts
Proventriculus: same as monogastric stomach and provides digestive excretions
Gizzard: located after proventriculus, very muscular, used to grind food

35. Avian Digestive Systems
Small Intestine
similar functions as in ruminants and monogastric systems
Large Intestine
“cloaca”: chamber into which urinary and genital canals open
“ceca”: aids in fiber digestion and absorption

37. Equine Digestive Systems
Characterized by non-ruminant animals that consume and digest feeds high in fiber

38. Equine Digestive Systems
Mouth
intact top and bottom incisors
molars adapted to chewing fibrous feeds
no digestive enzymes in saliva
Esophagus
not well adapted for regurgitation
connects mouth and stomach

39. Equine Digestive System
Stomach
similar to monogastric system
Small intestine
similar to monogastric and ruminant systems
no gall bladder to store bile
enlarged cecum to aid in fiber breakdown

40. Equine Digestive System
Large Intestine
similar to monogastric systems
cecum (at junction of small and large intestines) and colon take up most of the volume of the equine digestive system

42. Accessory Organs
Organs that aid in the digestive process without actually being part of the digestive system

43. Accessory Organs Pancreas Liver
produces and secretes digestive enzymes
produces insulin which regulates carbohydrate metabolism
Liver
produces bile-breaks down fatty acids
stores iron, handles fats and carbohydrates in the blood

44. The End!!