The Digestive System: Intestines and Absorption Human Bio 11.
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Transcript of The Digestive System: Intestines and Absorption Human Bio 11.
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The Digestive System: Intestines and AbsorptionHuman Bio 11
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Pyloric Valve
•The valve leading form the stomach to the small intestine.
•After 1–2 hours, it opens and chyme flows into through.
• It travels to the intestines where it is turned into a form the blood can absorb.
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Small Intestine
•About 7m long.
• It is coiled up in the lower abdomen.
•Most chemical digestion occurs here.▫More enzymes are here.
•Three parts:
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Small Intestine
•Duodenum:▫Bile and pancreatic juices are added to the
chyme.
• Jejunum: ▫Maximum absorption takes place here. ▫It is deep red because of all the blood
vessels.
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Small Intestine
• Ileum:▫Specifically responsible for absorbing
vitamin B12 and re-absorbing bile salts.
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Absorption
•The movement of nutrients from the digestive system to the blood.
•Nutrients must pass the lining of the digestive.
•Most absorption occurs in the small intestine.
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Absorption
•The folded surfaces of the small intestine are covered with thousands of finger-like projections called villi.
•These provide an enormous surface area for the absorption of nutrient molecules.
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Absorption
•Each villus is surrounded by capillaries and lacteals.
•Capillaries carry blood and receive carbohydrates and proteins.
•Lacteals carry lymph and receives fats. ▫Lymph eventually joins the blood, closer to
the heart.
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Large Intestine
•Bowel or Colon.
•About 1.5m long.
•Much larger in diameter than small intestine.
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Large Intestine
•Here food that was not digested (fibre) is prepared for elimination.
• It reabsorbs water and maintains the fluid balance of the body.
• It also absorbs certain vitamins.
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Rectum
•The last part of the large intestine and digestive tract.
•All non-digested food ends up here before being expelled by the anus.
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The Digestive Process
•Digestion and Absorption Animation