Alimentary Canal: Esophagus to Stomach

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  1. What is the length?
    esophagus--> end of the intestines or anal canal
  2. Wall of the alimentary canal.
    Beginning with the luminal surface, it has the tunica mucosa, tunica submucosa, tunica muscularis, tunica adventitious (or serosa)
  3. Explain the tunica mucosa.
    mucous memrane that is epithelium (type depends on organism) contianing mucous cells, which help protect the walls from digestive enzymes in the tube; also forms the digestive glands, which lie int he tunica mucosa
  4. Tunica submucosa
    CT layer that contains BVs, lymphatic vessels, and nerves, which are all part of the autonomic NS, which controls movement of the bolus through the tube (peristalsis)

    layer through which absorption occurs; the food enters the mucosa and then the submucosa, where it enters the capillaries and gets absorbed into the lymphatic system
  5. Tunica muscularis
    Made of smooth muscle.

    • There are two orientations to that smooth muscle:
    • - inner circular orientation and then an outer longitudinal layer
  6. Movement of the tunica muscularis
    The kind of movement that takes palce in the tube is a rhythmic movement called peristalsis, which moves the bolus down the tube

    This is controlled by the ANS
  7. Tunica Adventitious (or serosa)
    Just a CT layer, which anchors the tube to the body wall and that is found in the esophageal region and the rectal/ anal canal area

    - helps prevent friction
  8. What is serosa?
    It is a serous membrane which is CT and epithelium and is the peritoneum

    It is a double walled membrane: outer is parietal peritoneum and inner is the visceral peritoneum
  9. Visceral peritoneum
    on the surface of the viscera, which allows it some movement, whereas the esophagus is a more fixed region of the tube
  10. Esophagus
    • connects the pharynx to the stomach
    • It is in most vertebrates just a transport tube for food
    • the only vertebrates whose esophagus secretes some digestive enzymes are amphibians-- the esophagus has digestive glands to secrete a particular enzyme. It does not function in the esophagus, but releases its products there
    • No digestion
    • In some vertebrates that swallow large amounts of food at once, the esophagus acts as a temporary storage
  11. Stomach
    Vertebrate stomachs can have two shapes, depending on the animal's body: straight or J-shaped
  12. In all vertebrate stomachs,...
    • the mucosa is in irregular folds of mucous membrane called rugae
    • - empty stomach: all of these fold in 
    • - filled stomach: mucosa distends
    • Essentially, the function is to allow for distendability
  13. At the end of the stomach?
    is the pyloric sphincter, going around the tube to control passage to the next part of the tube
  14. Two major functions of the stomach
    1) churning: a movement in the alimentary canal where the bolus is thrown back and forth to break into small pieces; digestive enzymes are not gonna function properly in a solid mass of food; mix with gastric juice; chyme is the small bits of chewed food mixed with gastric juice; only in the stomach

    Begins the digestion of proteins: pepsinogen is a zymogen and HCl cleaves it into pepsin`
  15. Narrow region of the stomach is the __.
    pyloric valve
  16. What is the pyloric valve made of?
    pylorus--> smooth muscle that helps regulate flow of chyme from stomach to intestine
  17. Stomach in..
    - fish, amphibians, and reptiles:
    increses in specialization up the chain (becomes more differentiated/ specialized)
  18. Stomach in..
    - birds:
    divided into proventriculus (gastric glands) and ventriculus (gizzard), the latter of which is a muscular compartment where grain is chopped up (mechanical digestion)
  19. Stomach in..
    - mammals
    well developed, modified structure modified in (ruminants) that they display multiple chambers that help in the digestion of cellulose

    - reticulum, omasum, abomasum, rumen
  20. Reticulum
    forms "Cud," a chamber that holds chewed material so it can be regurgitated--> chewed
  21. Omasum
    chewed food mixed with water and salts
  22. Abomasum
    gastric glands and rugae (increase surface area) and is site of enzymatic activity
  23. Rumen
    where digestion via bacteria occurs (site of cellulose digestion)
Card Set:
Alimentary Canal: Esophagus to Stomach
2015-10-30 15:30:46
Test Three: Seitchik
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