Animal Nutrition

Digestion 1.Reduce size of food material to increase surface area 2.Kill unwanted microbes 3.Break down macromolecules into subunits 4.Absorb small molecules into the bloodstream

Types of Digestion Mechanical digestion –Teeth, mouth Enzymatic (chemical) digestion –Mouth –Stomach –Small intestine

Enzymatic Synthesis and Digestion of Organic Polymers Digestion Synthesis

Intracellular Digestion Enzymatic digestion Inside food vacuole

Extracellular Digestion Allows digestion of larger organisms Enzymes are secreted into gastrovascular cavity

Alimentary Canals Specialization Increased surface area

Human Digestive System

Dentition Carnivore –Grab, cut, crush Herbivore –Grind Omnivore

Tooth Function

Swallowing

Stomach Mechanical digestion –Peristaltic contractions Enzymatic digestion –Pepsinogen Enzyme precursor Converted to active form pepsin by acid –Digests proteins Acid kills unwanted microbes Some absorption of nutrients –Water and alcohol

Small Intestine Neutralization of acid –Pancreas produces alkaline (basic) secretions Enzymatic (chemical) digestion –Source of enzymes Small intestine Pancreas Emulsification –Bile salts from liver –Increases surface area of fat droplets

Small Intestine Absorption of digested molecules –Structure of small intestine increases surface area Villi and microvilli –Intestinal walls are filled with capillaries –Nutrients pass through intestine wall into capillaries and into the blood stream

Duodenum Approximately the first foot of the small intestine Ducts from pancreas and gall bladder enter here –Pancreas – bicarbonate, hydrolytic enzymes –Gall Bladder – bile

Pancreas Gland –Bicarbonate – neutralizes stomach acids –Hydrolytic enzymes Carbohydrates – Amylase, disaccharidases Proteins - Trypsin, chymotrypsin, aminopeptidase, carboxypeptidase, dipeptidase DNA and RNA - Nuclease, neucleosidase Fats - Bile salts, lipase

Carbohydrates

Protein Structure

Proteases Aminopeptidase Trypsin and chymotrypsin Carboxypeptidase

DNA and RNA

Lipids

Homeostasis

Enzyme Activation Pancreas secretes enzymes in inactive form Enteropeptidase found in small intestine activates the enzymes

Intestinal Wall Structure

Enzymatic Digestion

Gastrointestinal Tracts

Cellulose Digestion No multicellular animal can directly digest cellulose Microorganisms live in specialized intestinal cavities to digest cellulose

Rumination “Chewing Cud” Rumen –Microorganisms digest cellulose –Some nutrients absorbed through wall of rumen –Rumination (chewing cud) Reticulum and Omasum –Absorb water –Slowly pass material from rumen to abomasum Abomasum –True stomach –Digestion of microorganisms –Digestion of proteins

Ruminant Digestive Tract