HUMAN NUTRITION

NOTES

HideShow resource information
  • Created by: Thaarani
  • Created on: 02-04-11 08:58

Digestion

  • 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
1 of 4

ALIMENTARY SYSTEM

  • 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 ****.
  • Fibre not digested so gives muscle something solid to grip on to for peristalisis. Without enough fibre- people constipate = colon cancer.
2 of 4

KEY TERMS

  • 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
3 of 4

ABSORPTION

  • 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
4 of 4

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »