bio ch digestion.txt

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  1. What is Homeostasis?
    The ability to maintain a stable internal environment
  2. What kind of digestive system do vertebrates have?
    A complete digestive system.
  3. Describe the Alimentary Canal (Gastrointestinal Tract)?
    It is basically a tube with two openings. The two openings being the mouth and the anus.
  4. Name the 5 stages of processing food.
    • - Ingestion (mechanical processing and motility) - eating (chewing and swallowing)
    • - Secretion - release of digestive enzymes and other chemicals into DS
    • - Absorption - uptake of nutrients into body fluids
    • - Elimination - expulsion of undigested and unabsorbed materials
  5. What are the other associated organs and parts to GI tract?
    • - important linings
    • - muscles - Smooth muscle - involuntary muscle activity
    • - Sphincters = rings of muscle that open and close between parts of GI tract
  6. What are some accessory glands (part of DS) that secrete digestive enzymes?
    • - salivary glands - mouth
    • - pancreas
    • - liver
    • - gall bladder
  7. Decribe the first step in the process of digestion.
    Ingestion and Chewing - Take in food and break into smaller pieces. This increases the surface area for enzyme action and makes it easier to swallow. This is done with the lips, tongue, and teeth. Some chemical process (digestion) also occur in the mouth. The secretion of saliva from 3 sets of salivary glands in the mouth, which moistens and lubricates food. Saliva contains the enzyme saliva amylase, which partially breaks down complex carbohydrates (Starch, glycogen) into shorter polysaccharides (chains of sugars). Finally, the tongue forms the food into a bolus (pellet).
  8. Decribe the second step in the process of digestion.
    Swallowing - a voluntary muscle action (helped by the tongue) that passes food thru pharynx(= common area where the trachea [wind pipe] and esophagus [food tube] open). {The epiglottis blocks the opening of trachea}. The bolus passes thru the esophagus (involuntary). Bolus is moved by peristalsis = wave-like, involuntary smooth muscle contraction. The bolus goes to the stomach thru the esophageal sphincter, which prevents back flow.
  9. Describe the functions of the stomach.
    The stomach primarily functions as a storage sack. It has folds (called rugae) so that it can expand. The storarge of the stomach allows for periodic eating instead of constant eating. The stomach has three layers of muscle (vertical, horizontal, and diagonal), which allows for churning, or mixing, of food and assists in chemical activity.
  10. What about the gastric juices of stomach. Describe them.
    The gastric (stomach) juices are secreted by secretory, epithelial cells. Mucuous cells contain a protein called mucin, which makes mucous. Mucous coats the stomach and protects from the gastric juices. A hormone released by the blood stream called gastrin, which induces the secretion of other gastric juices. Along with the nervous system, gastrin controls stomach activity.
  11. How do parietal cells help with digestion?
    Parietal cells release hydrochloric acid (HCl), which kills ingested bacteria, denatures proteins, and activates pepsin.
  12. How do chief cells help the digestion process?
    Chief cells release pepsin, which is an enzyme that breaks some peptide bonds between amino acids in proteins. Proteins
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bio ch digestion.txt
2012-02-28 15:16:03
Biology Chapter Digestion

Chapter over digestion in Biology
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