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Digestive and Excretory Systems

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					Chapter 30 – Digestive and
   Excretory Systems
     Foods – these are necessary
•   Carbohydrates
•   Fats
•   Proteins
•   Vitamins
•   Minerals
•   water
Human Digestive System
  Digestion starts in the mouth
• Saliva starts mixing food
  with saliva
  - saliva comes from salivary
  glands in the cheeks and
  under the tongue.
   - saliva moistens food,
  mixes food with mucus, and
  adds enzymes that break down
  starch into sugars.
    Teeth carry out mechanical
             digestion
• Take care of your teeth
 Swallowed food passes into the
  esophagus then the stomach
• Peristalsis is responsible for pushing food
  in one direction through the rest of the
  digestive system after the mouth.
  – This occurs in the espophagus, stomach, small
    intestine, large intestine, rectum, and pushes
    wastes out of the anus.
      Digestive system problems:
•   Food poisoning
•   Parasites such as worms
•   Viral infections (hepatitis)
•   Eating disorders (anorexia and bulimia)
•   Diarrhea and constipation
•   Flatulence! (excuse me!)
          Excretory System
• Animals produce waste products that must
  be removed from their body.
• Most animals have a system that deals with
  nitrogen-rich wastes from the breakdown of
  proteins and nucleic acids.
• Ammonia (NH3) is toxic.
• In addition, it helps maintain homeostasis –
  balancing osmotic action and pH.
Human Excretory System
•
    Excretory System Problems
• Kidney stones – crystalized mineral salts and uric
  acid salts in the urine. Stones block flow of urine
  and cause excrutiating pain.
• Kidney failure - can be caused by long-term
  diabetes, infections, physical injuries, chemical
  poisoning. Causes toxic materials to build up to
  lethal levels.
  Dialysis or kidney transplant is the treatment.
The End

				
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posted:4/7/2008
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