Tuesday, April 5, 2011

The Digestive System

Today was a pretty average day in biology.



  1. First we handed in our flow map which was homework

  2. Then we took notes on the organs of digestion

  3. After we introduced the emzyme and nutrient lab

Homework:



  • Nutrient Pre-Lab due tomorrow

  • Read 30.2 fir tomorrow

  • Enzyme reading chart due thursday

  • Visit Me Extra Credit by Tuesday next week

Here are the notes in case anyone missed them, the next scribe is Dana!


Digestion:




  • breaks down large molecules into smaller molecules which can be used by cells


  • Physical & chemical, alimentary canal- one way tube which food passes through body


  • Acessory structures: dont carry food but aid in digestion

Mouth:




  • Mechanical digestion- teeth crush food


  • saliva moistens food and contains salivary amylase: turns starch into simpler sugars

Esophagus:




  • Muscular- connects pharynx & stomach Perisatlisis-waves of muscle contractions


  • bolus enters the stomach thru a sphincter, acid may back up into the esophagus

Stomach:




  • Muscular sac lined w/ mucus ~ protection & lubrication


  • mechanical digestion & chemical digestion

  • HCI kills bacteria lowers pH to activate pepsin


  • Peptic ulcer- hole in stomach wall: caused by bacteria

Small Intestine:




  • Duodenum- 1st part of the small intestine, enzymes & fluids enter here


  • Carbs, lipids, & proteins digested here, nutrients absorbed


  • lined w/ finger like projections called villi- increase surface area for absorption

  • water, cellulose, & indegestibles remain

Acessory Structures:




  • Liner produces bile which emulsifies fat, gallbladder stores bile, & oancreas produces enzymes Large Intestine:


  • absorbs water from undigested material & bacteria synthesize vitamin K

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