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Animal Science- Digestive Systems by LisaB1982

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									         Digestive System

Chapter #2
Digestive System

   Large complex molecules broken down
    into simpler molecules
   Long tube beginning with mouth and
    ending with the anus
Digestive Systems

   Man & Pig have a simple stomach with
    an extensive intestinal system
   Ruminants have a complex stomach
    with a simpler intestinal system
   Horses & Rabbits have a simple
    stomach with an extensive intestinal
    system and an enlarged cecum
        Digestive System
   Mouth: “Prehension” tool (grasps food)
   Salivary Glands secrete juices containing
    enzymes (digest food)
   Chewing food breaks down also
   Esophagus: muscular tube that connects
    mouth to stomach
   Peristaltic Movement: sequential contraction of
    ringlike muscles
   Reverse Peristalsis = blowing chunks
Simple Stomach

   Muscular contractions break down food
   Enzymes break down food:
    – Gastric: proteins
    – Liver & Pancreatic: fats
    Ruminant Stomach
   Stomach occupies 3/4 of abdominal
    cavity, mostly on the left side
   Rumen (paunch): 80% of stomach, lighter
    food collects here
    – microbes digest cellulose
    – lots of water
   Reticulum (hardware stomach): 5% of
    stomach, heavy foreign items are trapped
Ruminant Stomach

   Omasum (many plies): 8% of stomach,
    absorbs water
   Abomasum (true stomach): 8% of
    stomach, typical enzyme activity
   Rumination: regurgitation, rechewing
    of food
    Digestive System
   Small Intestine: long coiled tube
    connecting stomach to large intestine
    – rest of the digestion and absorbtion takes
      place here
    – surface covered with villi (surface area)
   Large Intestine: Cecum, colon, rectum
    – absorbs water (makes feces more solid)
    – some vitamins & minerals absorbed here
    – Cecal Fermenters (Horse): similar to rumen
Digestive System

   Accessory organs:
   Pancreas secretes enzymes to break
    down fat
   Liver (largest internal organ) secretes
    bile, which digests fats
    – also stores iron

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