Lecture 29 - Digestion I - Lecture 29 Digestion 1 A...

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Lecture 29 – Digestion 1 A. Introduction 1. Heterotrophic – we cannot make our own food (anything that is organic), it has to be preformed 2. Holotrophs – means “to swallow whole,” ingestive; some animals are herbivores (plant eaters), some are carnivores (meat eaters), some are omnivores (eat a combination of plants and animals) 3. Digestion (fig. 46-2) – taking the macromolecules (proteins, carbohydrates, lipids) 1) Hydrolytic – take the macromolecules (proteins, carbohydrates, lipids) and add water to break them down, and they have to be transported and rearranged into our own macromolecules. How does this occur? 2) Intracellular – phagocytic, breakdown occurs within the cells (protozoans, sponges) 3) Extracellular – we evolved extracellular digestion 1) Gastrovascular cavity – flatworms (planaria); hydra. Enzyjmes are secreted, they break down the food and they are absorbed. Combination of extracellular and intracellular 2) Alimentary canal – (tube w/i tube); (nematodes, annelids, mammals); extracellular
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This note was uploaded on 05/30/2008 for the course BS 131 taught by Professor Smith during the Spring '08 term at University of the Sciences in Philadelphia.

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Lecture 29 - Digestion I - Lecture 29 Digestion 1 A...

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