Chapter 30 – Digestive and
Excretory Systems
Foods – these are necessary
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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:
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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
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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