Digestion in Other Organisms

Week outline: Monday: Digestion in Other Organisms Tuesday: Science Center & Body Worlds – have Fun! Wednesday: Digestive System Quiz Digestive System Problems Due (Page 284 #1-11 inclusive) Med School 101 Start Respiratory System Thursday: Respiratory System Friday: Respiratory System in Other Organisms

Amoeba One-celled organism Does not have complex digestive system Uses phagocytosis for engulfing and ingesting food Requires energy from ATP Surrounds food by extensions of cytoplasm called pseudopods Once inside food is stored in a vacuole

Amoeba Food vacuoles move with the amoeba Enzymes that break down food are released into the vacuole Specific pH within vacuole allows enzymes to work at optimum

Earthworm Regions in their alimentary canal differ by function Worms burrow in ground – use prostomium to scoop soil Muscular pharynx sucks soil into mouth Nutrient-containing soil passes down esophagus

Earthworm Nutrient rich soil is stored and moistened in the crop No teeth – muscular gizzard: equipped with sand and gravel to help allow food from crop to enter (mechanical) Organic matter is chemically digested & nutrients are absorbed Indigestible material is eliminated through the anus

Bird Have alimentary canal similar to worm Able to eat a variety of food: insects, worms, berries, seeds Have a crop for storing food Have a gizzard for mechanically digesting food Gravel in gizzard help grind food into digestible pieces Chemical digestion in the stomach Nutrients absorbed in the intestine

Bird

Cow Ruminant mammals (cows, sheep, deer, etc) have more complex digestive system 4 chambers Because they digest cellulose (substance undigested by humans) Cow chews & swallows mouthful of grass then food enters the rumen Later travels into the reticulum

Cow Bacteria in rumen and reticulum start to break down cellulose Cow helps this process by regurgitating and re-chewing food from time to time “Rumination” or “chewing of the cud” – softens & helps break down plant fibers, making them more accessible to bacteria and more digestible

Cow

Digestive System Practice Problems Page 284 #1-12 inclusive Due Wednesday! Reminder: Digestive System Quiz Wednesday!