Comparative Digestive Systems Topic 3024 Amanda Moore Torey Birchmeier Modified by Ashlee Gibson

Digestive Systems Overviews

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

Parts of the Digestive Tract Accessory Organs Pancreas 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