Structure/ Function: 41

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DesLee26
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198938
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Structure/ Function: 41
Updated:
2013-02-08 16:06:16
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BIO 220
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Nutrition/ Digestion
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  1. Digestion in Porifera
    • intracellular digestion
    • carried out by choanocytes in a gastrovascular cavity called the spongocoel; the osculum opens to the outside of the spongocoel
    • There are porocytes that allow entry into the spongocoel. 
    • –INTRACELLULAR

    •Choanocytes

    • –The cells that will carry out intracellular digestion. They will digest
    • the food, take the nutrients, and pass them to associated cells, the amoebocytes; has a collar and large coelum; mucus, which catches the food, lines the collar

    •Amoebocytes

    • –Mobile cells
    • that will transport the nutrients to cells of the body that are not exposed to
    • the spongocoel
  2. Digestion in Cnidaria (hydra)
    • They carry out intracellular and extracellular digestion
    • They have a gastrovascular cavity with two cells, the inner cells lining the gastrovascular cavity are the gastrodermal cells, which will carry out intracellular digestion. They will release digestive enzymes that will digest the dead prey; afterwards, the gastrodermal cells will finish digestion intracellularly.
    • The gastrovascular cavity has one opening--the mouth--surrounded by tentacles. 
    • On the tentacles are cnidocytes, the cells that contain a trigger and nemadocyst that contains a coiled thread that will aid in capture of the prey and digestion. When a prey hits the trigger on the cnidocyte, it will cause the nematocyst to release the coiled thread and bring the prey to its mouth. The dead prey then gets extracellularly and intracellularly digested.
  3. Digestion in Platyhelmenthes (planaria)
    • they have thick walls, more cells, and a branching network (nerve net) to allow access and increase surface area of the organism; complexity needs branching for total access to the body
    • It has a mouth on its underside and can extend the pharynx out
    • the cells that line the gastrovascular cavity can release digestive enzymes on to prey  OUTSIDE of the body

    • --
    • where extracellular occurs, it only partially digests the prey

    • --
    • sucks up the pieces and the pieces are taken in by phagocytosis to the cells of the gastrovascular cavity where
    • digestion is completed intracellulary

    • Highly branched nature leads to endo and exocytosis of other cells
    • 1. Extra and intracellular digestion
    • 2. Different components:. Mouth, pharynx and gastrovascular cavity- highly branched
  4. Vertebrata (human)
    • Alimentary canal
    • One way flow
    • - two openings (mouth--> anus)
    • - compartmentalization; each compartment does a different job (specialized in other things)
    • Carries out absorption
    • - this is necessary to get the nutrients from the canal to the rest of the body
    • begins in the mouth--> pharynx--> esophagus--> stomach--> small intestine--> large intestine--> rectum--> anus
    • Accessory glands: salivary, pancreas, and liver (gallbladder stores bile, but isnt an accessory gland)
  5. Wall of the vertebrate digestive tract (from outer to inner)
    • tunica mucosa
    • tunica submucosa
    • tunica muscularis
    • tunica adventitia (or serosa in abdominal and pelvic region)
  6. Tunica Mucosa
    • Structure: glandular layer (simple columnar in humans) with goblet cells that release mucus for the lining of the alimentary canal 
    • Function: produces and secretes the digestive enzymes; protection (through mucus) from self-digestion
    • Location: lines cavities that open to the exterior
  7. Tunica Submucosa
    • Structure: contains blood vessels, lymphatic vessels, and nerves; connective tissue layer
    • Function: vessels are there to absorb/ transport nutrients; nerves are part of the autonomic nervous system, parasympathetic division: controls smooth muscle, cardiac muscle, and glands--> control movement of the tube and release of digestive juices
    • Location: second layer of the canal 
  8. Tunica Muscularis
    • Structure: smooth muscle and skeletal muscle at beginning and end (usually in the sphincter) [even though these structures are barely under control]
    • Function: contraction; move the food along to the next structure; peristalsis and churning (in the stomach)
    • Location: second to last layer of the tube
  9. Tunica adventitia (serosa)
    • Structure of adventitia: connective tissue
    • Structure of serosa (peritoneum): epithelial (serous) and connective tissue; it has two parts (parietal peritoneum and visceral endothelium with serous fluid in between)

    • Function: connection and binding of vessels and nerves to the tubes; and binding the tube to the wall
    • Function of Serosa: reduce friction as the organs move in the cavity

    • Location of serosa: in abdominal and pelvic region (SI, LI, stomach)
    • Location of adventitia: esophagus, mouth, pharynx
  10. Comparison of the Components of digestive tract among classes of vertebrates
    Mouth, Salivary Glands, Teeth
    • Mouth: begins mechanical digestion through teeth; in higher vertebrates, it begiins digestion of carbs (some amphibians and rest of vertebrates)
    • salivary glands (aquatic amphibians and fish don't have glands) all terrestrial animals do
    • Teeth: all vertebrates except birds have teeth; humans= heterodont and diphyodont; amphibians, reptiles, and fish= homodont and  polyphyodont
  11. Digestive Structures in Humans
    • mouth, salivary gland
    • pharynx
    • esophagus
    • stomach (fundus, pylorus, pyloric sphincter, rugae)
    • small intestine (plicae, villi, microvilli, duodenum, jejunum, ileum, Krypts of Lieberkhan)
    • large intestine (cecum, appendix, ascending, transverse, descending colon, sigmoid colon, rectum)
    • anus
    • pancreas
    • liver
    • gallbladder
  12. Comparison of the Components of digestive tract among classes of vertebrates
    Pharynx, Esophagus, Stomach
    • Pharynx: transport in all vertebrates; no digestion, except some ampibians have digestive glands, which secrete digestive juices, but it does not digest
    • Esophagus: transport tube; no digestion
    • Stomach: can be J shaped or straight; all begin digestion of proteins; rugae; pyloric sphincter
  13. Comparison of the Components of digestive tract among classes of vertebrates
    Small Intestine
    Large Intestine
    SI: two parts in all but mammals: duodenum and ileum/ mammals have three (a jejunum in the middle); at end of vertebrates in all organisms is the ileocecal sphincter; plicae and villi (in humans: microvilli)

    LI: absorption of water and some vitamins and formation of feces; cecum and appendix (no role in man); animals have a cloaca, while humans have an anus
  14. Comparison of the Components of digestive tract among classes of vertebrates
    Pancreas
    Liver
    Fish have two; all other animals have one

    Liver: largest gland in body (in fish, its HUGE); PRODUCES bile

    Gallbladder: grain-eating birds don't have a gallbladder

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