HUMAN NUTRITION

• 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:-
• MECHANICALLY
• teeth, tongue
• CHEMICALLY
• enzymes

• 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.

• Pancrease
• 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

• 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