By: Kristy Baird

•Describe the basic function of the primary components of the digestive system.
• Compare the function and location of the digestive organs to those in the monogastric, modified monogastric and ruminant digestive systems.
• Explain the difference between and identify diagrams of the different types of digestive systems of various animals.

The process by which large complex nutrient molecules are broken down into simpler molecules capable of being used by the organism for food.

Humans, swine, rabbits, chickens and horses all have a simple stomach, which is also known as a monogastric digestive system.

Known as a modified monogastric system

Parts and functions of the monogastric avian digestive system
•Mouth/Beak - gather and break down feed
• Esophagus - tube from mouth to stomach that is open at the mouth end
• Crop - feed storage and moistening
• Proventriculus - glandular stomach (HCI and gastric juices); enzymatic
• Gizzard - muscular stomach; mechanical breakdown

Parts and functions of the monogastric avian digestive system continued…
•Small Intestine - enzymatic digestion and absorption
-Functions of the small intestine: digestion of proteins, carbohydrates, and fats; absorption of the end products of digestion
-Enzymes in the small intestine
• Ceca - essentially non functioning in monogastrics
• Large Intestine
-bacterial activity
-water absorption
-waste storage
• Cloaca - common chamber for GI and urinary tracts
• Vent - common exit for GI and urinary tracts

Parts and functions of the monogastric mammal digestive system
•Mouth
-gather and chew feed using tongue and teeth
-salivary glands moisten feed to aid in swallowing
-saliva begins the carbohydrate breakdown with salivary amylase
• Esophagus
tube from mouth to stomach that is open at the mouth end
-separated from stomach by the esophageal sphincter
• Stomach
-muscular gland lined sac that receives ingesta from the esophagus and conducts both physical and chemical digestion
-primary secretions:
pepsin - enzyme that digests protein;
hydrochlorides - acids that aid in protein digestion

Parts and functions of the monogastric mammal digestive system continued…
•Small Intestine
-enzymatic digestion and absorption
-Functions of the small intestine: digestion of proteins, carbohydrates, and fats; absorption of the end products of digestion
1. duodenum - most digestion occurs here
2. jejunum - some digestion and some absorption occur
3. ileum - mostly absorption
-
Bile - made in liver, stored in gall bladder, active in the small intestine, emulsifies fat to aid in digestion

Parts and functions of the monogastric mammal digestive system continued…
•Enzymes in the small intestine

Parts and functions of the monogastric mammal digestive system continued…
•Cecum - essentially non functioning in many monogastrics. Rabbits and horses have an enlarged cecum that acts like a rumen and is involved with microbial digestion (fermentation)
• Large Intestine
-bacterial activity
-water absorption
-waste storage

Sheep, cows, and goats are examples of animals with complex stomachs, which are also known as ruminant digestive systems

Parts and functions of the ruminant digestive system
Ruminants are characterized by having a stomach with four compartments
3.
4.
5.
1.
2.
6.
Anus
Rectum
Cecum
Colon
Duodenum
Rumen
7. Reticulum
8. Esophagus
9. Abomasum
10. Omasum
11. Small Intestine
Rumination - the regurgitation, rechewing and reswallowing of ingested food
Cud - mass of regurgitated ingesta; bolus
Process of rumination
1. regurgitate bolus from rumen
2. rechew and reinsalivate
3. reswallow
4. repeat with another bolus

Parts and functions of the ruminant digestive system continued…
• Mouth
-contains dental pad, teeth, tongue and saliva
-saliva contains no salivary amylase
• Esophagus
-tube from mouth to stomach
-tube from stomach to mouth

Parts and functions of the ruminant digestive system continued…
• Rumen - large fermentation vat; also called the "paunch"
-anaerobic
-Temperature = 39 o C (103 o F)
-saturated with gasses
-constant motion
Lining of the rumen

Parts and functions of the ruminant digestive system continued…
• Functions of Microorganisms
-digest roughages to make Volatile Fatty Acids
-make protein
-make vitamins K and B complex
(Very similar to cecum of rabbit and horse)
The function of the rumen is to house microorganisms.

Parts and functions of the ruminant digestive system continued…
• Reticulum - "honeycomb"
-houses microorganisms
-catches hardware (ingested by animal)
-houses the opening to the omasum
• Omasum - "manyplies“ or “book”
-full of folded tissue
-water absorption
• Abomasum - true stomach
-pepsin
-HCl

Parts and functions of the ruminant digestive system continued…
•Small Intestine
-enzymatic digestion and absorption
-Functions of the small intestine: digestion of proteins, carbohydrates, and fats; absorption of the end products of digestion
1.duodenum
2.jejunum
3.ileum
•Cecum - some microbial fermentation
•Large Intestine
-water absorption
-waste storage

Pigs, Rabbits, Horses, Chickens, and Humans have a simple stomach or a monogastric digestive system
Cows, Sheep and Goats have a complex stomach or a ruminant digestive system

What type of digestive system is this?
Ruminant

What type of digestive system is this?
Avian
Monogastric
System
(modified monogastric)

What type of system is this?
Monogastric