- Large insoluble molecules converted to small soluble molecules and therefore
1) absorbed into blood across a villa membranes
2) small molecules are soluble in plasma
- Digestion is done in two different ways:-
- teeth, tongue
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- Bucal Cavity- mechanical digestion/food chewed. To increase surface area so enzymes can get to it more. Savliary glands secrete saliva which amylase
- Smal Intestine- 6m long and narrow. Food carries from the stomach and is acidic. Bile is made in liver and stored in gall bladder. Goes down in small intestine a) neutralises acid - pH2 from stomach b)emulsifies fat.
- Oesophagus- gullet carries food from mouth to the stomach. Food is moved by PERSITALIS
- Stomach- stomach wall secretes 1)pepsin (a protease) 2) HCL because pepsin works best at pH2 protein --> amino acids
- Pancrease- sends enyzmes into SI.
- The food is moved through the small intestine by peristalisis- circular muscles just behind the food contract, so food is pushed on. A wave of contraction down the SI moves food through
- Large intestine- fibre,dead bacteria and mucus goes to LI. The body absorbs water into blood so material becomes more solid-faces. The faces leave body at anus.
- Fibre not digested so gives muscle something solid to grip on to for peristalisis. Without enough fibre- people constipate = colon cancer.
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- Amlyase- starch --> maltose ( produced by salivary glands)
- Protein --> amino acids
- Lipids --> fatty acids and glycerol (produced by pancrease
- INGESTION: putting food into mouth
- DIGESTION: large insoluble molecules into small,soluble molecules
- ABSORPTION: taking products of digestion from SI into blood
- ASSIMILIATION: building new molecules the cells with products of digestion
- EGESTION: removal of wastes not made by body
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- In SI all food is digested starch digested into sugar. All proteins are digested into amino acids.Lipids are digested into fatty acids and glycerol.
- The SI is well adapted at aborbing food because vill:-
- Large s/a so food can be absorbed
- Thin villus wall is 1 cell thick- therefore there is a short diffusion halfway means that when the particles diffuse they dont have far to go
- Good blood supply- food can be absorbed so more blood goes through, more food goes through
- Water soluble food- diffues into blood (sugars,amino acids,minerals and Vit B,C- water soluble food)
- Blood flows quickly through villus so food is more concentrated outside so it keeps on diffusing into the blood
- Lacteal absorbs fat soluble food 1) fatty acids and glycerol 2)vitamin A,D,E
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