SPEC: The gross structure of the human digestive system limited to oesaphagus, stomach, small and large intestines, and rectum. The glands associated with this system limited to the salivary glands and the pancreas.
Digestion= process in which large molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed and assimilated. (Absorbed= taking soluble molecules into the body) (Assimilation= incorporating small molecules into the body) Note: p18 in AS Biology Nelson Thornes book |
FACT FILE:
OESOPHAGUS Function: Think of it as the road the taxi (food) uses to get from A (mouth) to B (stomach). Therefore it is responsible for TRANSPORT and not digestion. It has a thick MUSCULAR wall. S.INTESTINE Long MUSCULAR tube with many folds (villi) to provide large S.A. This is increased more by microvilli on the epithelial cells of each villi. Function: - enzymes in its walls secrete enzymes to digest food further - provide a large S.A for absorption of digestion products into the bloodstream |
Below=villi with microvilli
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FACT FILE
STOMACH Function: -store, digest food (especially proteins) Glands are to: -produce ENZYMES- to digest protein -produce MUCUS- prevent it being digested by its own enzymes L.INTESTINE Function: - absorb water (so food here becomes drier, thicker; thus forming faeces) RECTUM Function: - store, periodically remove faeces (via anus) |
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Enzyme Produced in the? Catalyses breakdown of? Where is it used?
Amylase - salivary glands -starch -> sugar (glucose) - mouth
- pancreas - s.intestine
- s.intestine
Protease - stomach - proteins -> a.a -stomach
- pancreas - s.intestine
- s.intestine
Lipase - pancreas - fats & oils -> fatty acids & glycerol - s.intestine
- s.intestine
Amylase - salivary glands -starch -> sugar (glucose) - mouth
- pancreas - s.intestine
- s.intestine
Protease - stomach - proteins -> a.a -stomach
- pancreas - s.intestine
- s.intestine
Lipase - pancreas - fats & oils -> fatty acids & glycerol - s.intestine
- s.intestine
It is important to chew food and make food as small as possible as this increases the S.A for maximum and rapid absorption of the digestion products.
Lactose Intolerance:
This is where the body is INCAPABLE of digesting LACTOSE into its constituent monosaccharides (glucose & galactose) which are smaller molecules and would be easier to digest (as they can diffuse through s.intestine wall). It is caused by low levels of LACTASE in the body, resulting in it being fermented by bacteria to cause symptoms such as bloating and diarrhea.
Lactose Intolerance:
This is where the body is INCAPABLE of digesting LACTOSE into its constituent monosaccharides (glucose & galactose) which are smaller molecules and would be easier to digest (as they can diffuse through s.intestine wall). It is caused by low levels of LACTASE in the body, resulting in it being fermented by bacteria to cause symptoms such as bloating and diarrhea.