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Digestion _amp; Respiration


									Jordan Bustard
•    Where do you think digestion begins?
     Most people automatically think of the
     stomach when they think of digestion.
     Actually, though, digestion starts in the
     mouth as the first workstation in the
     digestive process.

    Food, of course, is ground up by our
    teeth. We chew without thinking. The
    jaw muscles pull the jaw up and down,
    thereby crushing the food and making it
    softer and smaller.

      When you are chewing, glands make
     saliva. Two quarts of saliva are
     produced each day. Saliva is constantly
     produced, but more of it is made when
     we eat. Smelling, seeing, or thinking
     about food gets the process of making
     more saliva started. Talk about a
     mouth-watering meal!
 •   the duodenum, the C-shaped first
 •   the jejunum, the coiled
 •   the ileum, the final section that
     leads into the large intestine

The inner wall of the small intestine is
covered with millions of microscopic, finger-
like projections called villi. The villi are the
vehicles through which nutrients can be
absorbed into the body.
•   the stomach, food undergoes chemical and
    mechanical digestion. Here, peristaltic contractions
    (mechanical digestion) churn the bolus, which
    mixes with strong digestive juices that the stomach
    lining cells secrete (chemical digestion). The
    stomach walls contain three layers of smooth
    muscle arranged in longitudinal, circular, and
    oblique (diagonal) rows. These muscles allow the
    stomach to squeeze and churn the food during
    mechanical digestion.

     Powerful hydrochloric acid in the stomach
     helps break down the bolus into a liquid called
     chyme. A thick mucus layer that lines the
     stomach walls prevents the stomach from
     digesting itself. When mucus is limited, an
     ulcer (erosion of tissue) may form
•     Your body does the same thing every day.
      Hidden throughout your body are dangerous
      poisons that must be removed in order for it
      to survive. The process of excretion involves
      finding and removing waste materials
      produced by the body.

    The primary organs of excretion are the lungs,
    kidneys, and skin. Waste gases are carried by
    blood travelling through the veins to the lungs
    where respiration takes place. Dead cells and
    sweat are removed from the body through the
    skin which is part of the integument system.

    Liquid waste is removed from the body through
    the kidneys. Located beside the spine in your
    back within your ribcage, the kidneys are small
    (about 10 centimetres long) reddish-brown
    organs that are shaped like beans.

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