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P 665 Sponges: Phylum Porifera Sponges: Feeding Animal Systems: Digestion Phylum Cnidaria: Feeding Carnivores Cnidocytes – stinging cells located on tentacles nematocysts – poison-filled stinging structure that paralyze or kill prey gastrovascular cavity - for digestion Central mouth surrounded by numerous tentacles filter feeders – take in tiny particles of food from water pores - openings where water enters choanocytes – cells with a flagella that trap and engulf tiny particles and move water through sponge osculum – a large opening where water and wastes exit Figure 26–12 The Polyp and Medusa Stages Section 26-3 Epidermis Mesoglea Gastroderm Tentacles Mesoglea Gastrovascular cavity Mouth/anus Mouth/anus Gastrovascular cavity Tentacles Medusa Polyp Go to Section: 1 Flatworms: Phylum Platyhelminthes Feeding/Digestion • • • Have a single opening or mouth located at the end of a muscular tube called the pharynx which can be extended when feeding Pathway: pharnyx, mouth, digestive cavity (intestine) where food diffuses to cells of body Carnivores, some are parasites Parasitic flatworms have hooks and suckers for attachment to host Roundworms: Phylum Nematoda Feeding/Digestion Roundworms – some are parasitic Hookworm is an intestinal parasite of humans that causes mild diarrhea and abdominal pain The barely visible larvae penetrate the skin (often through bare feet) carried to the lungs, go through the respiratory tract to the pharnyx, are swallowed, and eventually reach the small intestine. In the small intestine, the larvae develop into half-inch-long worms, attach themselves to the intestinal wall, and suck blood. can either be carnivorous, herbivorous, or parasitic Some have grasping mouth parts Nutrients are transported throughout body via fluid in pseudocoelom Pathway: mouth, pharynx, intestines, anus Roundworms – some are parasitic Ascaris - most common human worm infection. tropical and subtropical areas where sanitation and hygiene are poor An estimated 1.5 billion humans infected; rare in U.S. Infection occurs when a person accidentally ingests (swallows) infectious Ascaris eggs Once in the small intestines, immature worms hatch from the eggs The larvae are carried through the lungs and then to the throat where they are swallowed Once swallowed, they reach the intestines and develop into adult worms. Adult female worms lay eggs that are then passed in feces 2 Roundworms Roundworms Elephantiasis •worms block the body's lymphatic system-a network of channels, lymph nodes, and organs that helps maintain proper fluid levels in the body by draining lymph from tissues into the bloodstream. •This blockage causes fluids to collect in the tissues, which can lead to great swelling, called "lymphedema." Segmented worms: Phylum Annelida Feeding/Digestion Pathway: mouth, pharynx, crop, gizzard, intestines, anus Extends pharynx to get food Crop – stores food Gizzard – grinds food Some filter feeders (aquatic) Some predators with jaws Phylum Arthropoda: Feeding/Digestion •Pathway: mouth/foregut, pharynx, esophagus, stomach/midgut, hindgut, anus •Midgut - (where special enzymes digest food also where absorption occurs) •Many different types of mouthshighly adapted to food source Chelicerae •Spiders have venom –poisonus fluid •Some have chelicerae (ex: spiders) 3 Phylum Mollusca: Feeding/Digestion Arthropod feeding • • • Termites – destroy structures Ticks/mosquitoes – transmit disease Bees- aids in flowering plant reproduction Pathway: 2 openings Have siphon that takes in water/particles Snails have a radula- contains hundreds of tiny teeth some can drill through shells for food Octopus has sharp beak for tearing food Contain muscular foot (tentacles are modified feet) Mollusks - filter feeding Mollusk - snails have a radula for scraping algae Mollusks - radula Phylum Echinodermata Feeding & Digestion Mollusks occupy many trophic levels: Carnivores Parasites Herbivores Filter feeders Extracellular digestion starfish feed on bivalves by opening shells, pushing stomach inbetween shells and partially digesting the organism before pulling the stomach back to original position to complete digestion. Occupy variety of trophic levels including, carnivore, herbivore, detritivores Contain digestive glands in arms Feathery star that catches food with its tentacles and then eats each one at a time. 4 Echinoderms Variety of niches as part of an ecosystem Predators thus controlling the number of organisms in a population Control algae population Some feed on coral which is a problem in reefs. Crown-of-Thorns starfish above has eaten the coral in the white area. It is termed a feeding scar. Vertebrate chordates have similar digestive pathways Phylum Chordata: Fish - Digestion Chordate Cladogram Section 30-1 Birds Amphibians Mammals Reptiles Fishes Nonvertebrate chordates Pathway: mouth -> esophagus -> stomach -> pyloric ceca -> intestine ->anus Liver, gall bladder and pancreas – secrete enzymes into digestive system that help break down food All modes of feeding (herbivore, carnivore, etc) Invertebrate ancestor Go to Section: Phylum Chordata: Amphibian Digestion Figure 30–11 The Anatomy of a Fish Section 30-2 Kidney Pyloric cecum Stomach Vertebra Muscle Esophagus Swim bladder Spinal Gills cord Brain Mouth Pathway: mouth, esophagus, stomach, small intestine, large intestine, cloaca Have liver, gallbladder, pancreas Operculum Urinary bladder Heart Anus Reproductive organ Pancreas Intestine Gallbladder Liver Go to Section: 5 Amphibian digestion Phylum Chordata: Reptilian Digestion Phylum Chordata: Digestion Bird Pathway: mouth, esophagus, crop, stomach/gizzard (2 part), intestines, cloaca Have liver, gallblader, pancreas Use large amounts of calories, therefore they eat a lot! Beak adapted to food source Phylum Chordata: Mammals Digestion Complete, complex, digestive system Specialized Teeth Jaws Pathway: (similar to amphibians); mouth, esophagus, stomach, small intestine, large intestine, cloaca Have liver, gallbladder, pancreas Some metabolize food slowly (snakes) and only need to eat once a month after a large meal Some are herbivores, some carnivores Bird Digestion Figure 33–8 The Digestive Systems of Vertebrates Section 33-3 Esophagus Shark Salamander Lizard Pigeon Cow Stomach Intestine Liver Gallbladder Pancreas Cloaca Crop Gizzard Cecum Rectum Go to Section: 6 Human nutrition & digestion 6 major nutrients: 1. 2. 3. 4. 5. 6. Water Carbohydrates Fats Proteins Vitamins Minerals Concept Map Section 38-1 Nutrients include http://www.mypyramid.gov/ Carbohydrates Fats Proteins Vitamins Minerals include are made of are made using include include Video Simple Complex such as such as Sugars Starches Amino acids Fatty Acids Calcium Iron Glycerol Fat-soluble Nutrient Label Quiz Watersoluble Go to Section: Human Digestion • Mechanical and chemical breakdown of food into molecules • Food molecules are broken down by enzymes • Digestive enzyme chart on p.981 • Peristalsis – rhythmic contractions of smooth muscle throughout entire digestive system Figure 38–10 The Digestive System Section 38-2 Mouth Pharynx Salivary glands Esophagus Liver Gallbladder (behind liver) Digestion Pathway 1. Mouth Mechanical and chemical digestion Salivary glands produce saliva Saliva contains amylase, an enzyme that breaks down starch Stomach Pancreas (behind stomach) Large intestine 2. Pharynx Small intestine Rectum Video Go to Section: 7 Digestion Pathway 3. Esophagus Connects mouth to stomach Digestion Pathway 4. Stomach Mechanical and chemical digestion Breaks proteins apart Cells secrete HCl (an acid) and proteases Ph is approx 3!! Contains chyme – soupy fluid of food, HCl, and enzymes Digestion Pathway Figure 38–14 The Small Intestine Section 38-2 Small Intestine 5. Small Intestine Absorbs nutrients into blood stream contains folds with villi and microvilli to increase surface area for absorption 6 meters long Duodenum – first section; completes digestion Villus Circular folds Epithelial cells Villi Capillaries Lacteal Vein Artery Go to Section: 8 P. 983 Digestion Pathway 6. Large intestine (Colon) 1 meter long 3 straight segments compacts undigested materials, absorbs water, and excretes waste from body Contains “helpful” bacteria Other organs involved in digestion: Liver Produces bile Supplies quick energy by releasing sugar into blood Detoxifies alcohol and poisons Gall Bladder – stores bile 9 Figure 38–13 The Liver and the Pancreas Section 38-2 Other organs involved in digestion: Pancreas Liver Gallbladder Duodenum Bile duct Pancreas Pancreatic duct Regulates blood sugar by producing: Insulin – lowers blood sugar levels Glugagon – increases blood sugar levels To rest of small intestine Go to Section: 10