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Diges t ion

Diges t ion. Human Digestion (mammals) Chapter 32.2 and 32.3 Comparative Physiology (comparing digestion in a variety of organisms) ~this information isn’t available in your book in a single chapter location, but this information is test material~. Mechanical Digestion.

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Diges t ion

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  1. Diges t ion Human Digestion (mammals) Chapter 32.2 and 32.3 Comparative Physiology (comparing digestion in a variety of organisms) ~this information isn’t available in your book in a single chapter location, but this information is test material~

  2. Mechanical Digestion • Physical change – breaking into smaller pieces, mixing, etc. • Ex – chewing • Purpose – to increase surface area available for reactions to occur

  3. Chemical Digestion • Use of enzymes to break food into smaller subunits (monomers) • Carbs  monosaccharides • Proteins  amino acids • Lipids  glycerol & fatty acids • Chemical change • Ex – protein broken into amino acids by pepsin

  4. http://www.biocourse.com/mhhe/bcc/resources/concept.xsp?id=000012109&type=MOVIE (animation of whole process)

  5. Your Digestive System • Overview of each organ’s function: http://kidshealth.org/kid/htbw/digestive_system.html • Digestion in action: http://kitses.com/animation/swfs/digestion.swf

  6. Sponges Sessile (attached to something, not moving) Filter feeders – they eat by straining particles from the water No true digestive system Digestion Across Kingdoms - Sponges

  7. Cnidarians (jellyfish & hydra) • Capture prey, often by use of stinging tentacles • Prey is stuffed into mouth which leads to gastrovascular cavity • This cavity has cells that secrete digestive enzymes and absorb nutrients • Wastes are eliminated through the mouth

  8. Planaria (type of flatworm) • Mouth is on the bottom of the worm • Mouth leads to gut cavity • Pharynx extends out of mouth to get food and bring it in

  9. Tapeworms (flatworms) • Adult worm does not swallow food • Segmented worm – absorbs nutrients from digested food it lives in

  10. All Other Bilateral Organisms Earthworm • Have complete digestive tract with 2 openings (mouth and anus) at opposite ends of a continuous tube • Food moves one way through the gut • Has specialized areas for digestion and absorption • Complete digestive tracts allow organisms to eat continuously Mollusk (clam)

  11. Echinoderms (sea stars, etc.) • Sea stars have complete digestive systems with a mouth, stomach, small length of intestine and anus. • Uses tube feet to grab food • It pushes its stomach outside of its body and digests the food in its stomach but outside of the body Sea Star

  12. Arthropods (crustaceans, insects and arachnids) • Crustaceans have mandibles for crushing and biting food before ingestion • Insects eat by either chewing or sucking • Arachnids either mash up food and push it into their mouths or they inject venom into their prey and then suck the digested nutrients out • All have a continuous tube that is open at both ends

  13. Arthropods

  14. Fish • Fish have a mouth, throat, areas for absorption and areas for compaction of waste. • Differences in diet result in small changes in size of each of these areas, including teeth shape, presence of stomach, etc. Carnivorous fish (have stomach) Omnivorous fish (do not have stomachs)

  15. Amphibians and Reptiles • Amphibians and reptiles have very similar digestive systems: a mouth, esophagus, stomach, small intestine, large intestine and a rectum.

  16. Birds • The stomach has two chambers. • The gizzard is used to grind up very hard items (it relies on ingestion of grainy materials to help) • Some have a crop to store food after eating. stomach

  17. Bacteria • Bacteria don’t have a digestive system • They absorb the nutrients they need for energy and building other compounds • Different types of bacteria have different sources for energy and carbon

  18. Protists • Protists take in food through phagocytosis (active transport process by which the cell membrane folds outwards around the object to be taken into the cell and then deposits the material inside the cell). • The materials taken in via active transport are then digested in vesicles that contain digestive enzymes

  19. Fungus • Fungi absorb their food from their environment • As fungi grow, their extensions (hyphae) release digestive enzymes into the food sources • As the food is broken down, the fungi absorb the nutrients through their cell walls

  20. Plants • Plants do not have a digestive system • All organisms need energy (characteristic of life) • Plants absorb sunlight energy to make sugars (photosynthesis) – they are autotrophs • They then break down the sugars to convert them to cellular energy (ATP) through cellular respiration • They absorb water and other nutrients through their roots

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