Peristalsis

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Major parts
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Two types of digestion

• Physical (mechanical)- chewing food ? smaller
  pieces
• - increases surface area for chemical digestion
  to act upon
• 2. Chemical (enzymes!)-break bonds in polymers to
  make monomers
• starch?simple sugars monsaccharides
• protein?amino acids
• Lipids? glycerol fatty acids

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Mouth

• Teeth-physical
• molars and incisors
• Saliva-chemical
• make 1.5 L a day, 98 water
• 3 functions
• dissolve food
• starch digestion (amylase breaks starch ? maltose
• kills bacteria
• Bolus-name for ball of food particles when
  swallowed

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Parts

• Epiglottis- flap that keeps food out of trachea
  guides it down esophagus
• Pharynx-nose/mouth connection
• Esophagus-made of smooth muscle, about 25 cm
  long, takes bolus about ten seconds to get to
  stomach
• Peristalsis-rhythmic contractions of smooth
  muscle to push food through esophagus

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Peristalsis
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Stomach

• 2 to 6 hours after swallowing
• Cardiac sphincter- food from esophagus? stomach
• Mucus-protects cells from acid
• HCl-low pH helps break bonds in polymers
• Pepsin-enzyme responsible for protein digestion
• Most protein digestion occurs here
• Chyme-new name for bolus is after leaving the
  stomach
• Pyloric sphincter- food from stomach? small
  intestine

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smooth muscle
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Small Intestine

• About 21 feet long! (not small)
• Duodenum- 1st part of the s.i.
• Jejunum 2nd part of the s.i.
• Ileum- 3rd part of the s.i.
• Villi-about 5 million folds in the small
  intestine increase surface area for absorption to
  occur (make it about 10X larger!)
• Microvilli along the villi increase surface area
  even more
• Carbohydrate digestion-the rest are digested here
  
• Fat digestion- w/ the aid of pancreatic enzymes
  bile (more later)
• Protein digestion- the rest occurs here

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More Parts

• Liver- produces bile, stores glycogen
• digests fats by secreting bile
• breaks down alcohol (alcohol dehydrogenase)
• Bile- yellow/green liquid that emulsifies fats
• Gall Bladder-stores bile
• Pancreas-secretes several digestive enzymes
• Amylases, lipases, proteases
• Also releases sodium bicarbonate to buffer
  acidity of the stomach
• Appendix-vestigial organ

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Large Intestine (a.k.a. Colon)

• Minerals vitamins are absorbed here
• 3 main parts
• ascending colon
• transverse colon
• descending colon
• Feces (solid waste) formation
• Water removal
• constipation and diarrhea occur when the amount
  of water removal is incorrect

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Large Intestine
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Thats The End!