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Plans and Locations - Where the digestion of the food...

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Plans and Locations The digestive system uses mechanical and chemical methods to break food down into nutrient molecules that can be absorbed into the blood. Once in the blood, the food molecules are routed to every cell in the animal's body. There are two types of animal body plans as well as two locations fordigestion to occur. Sac-like plans are found in many invertebrates, who have a single opening for food intake and the discharge of wastes. Vertebrates, the animal group humans belong to, use the more efficient tube-within-a-tube plan with food entering through one opening (the mouth) and wastes leaving through another (the anus).
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Unformatted text preview: Where the digestion of the food happens is also variable. Some animals use intracellular digestion , where food is taken into cells by phagocytosis with digestive enzymes being secreted into the phagocytic vesicles . This type of digestion occurs in sponges, coelenterates (corals, hydras and their relatives) and most protozoans. Extracellular digestion occurs in the lumen (or opening) of a digestive system, with the nutrient molecules being transferred to the blood or some other body fluid. This more advanced type of digestion occurs in chordates, annelids, and crustaceans....
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