Digestive System Notes

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Digestive System Notes
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Basic Outline

• 1. Movement propels food through the digestive
  system
• 2. Secretion release of digestive juices in
  response to a specific stimulus
• 3. Digestion breakdown of food into molecular
  components small enough to cross the plasma
  membrane

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• 4. Absorption passage of the molecules into the
  body's interior and their passage throughout the
  body
• 5. Elimination removal of undigested food and
  wastes

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Hungry?

• The average male will eat about 50 tons of food
  (during his lifetime!) in order to sustain a
  weight of 150 lbs.

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Lets Dig In!!!!
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Mouth

• receptacle for food
• begins mechanical digestion through chewing
• swallow food

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Esophagus

• A simple conduit between the mouth and stomach

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Did you know ?

• It takes about 8 seconds for food to travel down
  the esophagus. The average time for your stomach
  to digest a high fat meal is 6 hours, as compared
  2 hours for a carbohydrate meal. The average time
  for the digestion process in the small intestine
  is about 3 to 5 hours. This is followed by
  another 4 hours to 3 days(!) in the large
  intestine.

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Stomach

• Short-term storage reservoir
• Substantial chemical and enzymatic digestion is
  initiated, particularly of proteins.
• Liquefaction of food
• Slowly released into the small intestine

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Did you know ?

• Your stomach produces a new lining every 3 days
  in order to avoid digesting itself in its own
  production of acid.

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Liver, Pancreas and Gallbladder

• Liver The center of metabolic activity in the
  body - provides bile salts to the small
  intestine, which are critical for digestion and
  absorption of fats.
• Pancreas provides a potent mixture of digestive
  enzymes to the small intestine which are critical
  for digestion of fats, carbohydrates and protein.
  
• Gallbladder stores and concentrates bile, and
  then releases it into the duodenum to help absorb
  and digest fats.

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Small Intestines

• This is where the final stages of chemical
  enzymatic digestion occur and where almost all
  nutrients are absorbed.

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Large Intestine

• In all animals water is absorbed, bacterial
  fermentation takes place and feces are formed.
• Herbivores like the horse, the large intestine is
  huge and of critical importance for utilization
  of cellulose.

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How long are your intestines?

• At least 25 feet in an adult. Be glad you're not
  a full-grown horse -- their coiled-up intestines
  are 89 feet long!

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Rectum/Anus

• RectumIt is the rectum's job to receive stool
  from the colon, to let the person know that there
  is stool to be evacuated, and to hold the stool
  until evacuation happens.
• Anus The anus is the last part of the digestive
  tract.

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Perils of Overeating
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• The next slide has a map of the digestive system.
  Your notes need to include a map and youll need
  to be able to label parts. You can choose to
  copy figure included in these notes or figure
  38-10 on page 979 in your textbook

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