1. Digestion and Absoption
Digestion of nutrients.
(Pre cooking of foods helps all this).
Food eaten is broken down by digestion. Only digested food can be absorbed
All this in digestive system (from mouth to anus)
These things occur by physical and chemical break down.
Physical breakdown
First physical breakdown: mastication
Second physical breakdown: muscular action (like peristalsis)
As a result: reduction of food size
Chemical breakdown
Chemicals or digestive juices are produced.
They contain enzymes (speed up chemical reactions)
Specific enzyme for specific reaction (many enzymes)
(for example: ”lipase” breaks down lipids, “amylase” breaks down starch)
Absorption of nutrients
Occurs in small intestine, alcohol is the only substance which can be absorbed
elsewhere.
Food takes 2-3 hours to pass along small intestine.
Walls of intestine with thousands of projections called villi.
Each villus surrounded by wall of cells, through which the nutrients pass.
In the center called lacteal only fats and fat soluble vit. Tiny blood capillaries
the rest of the nutrients.
Pass to blood capillaries:
GLUCOSE (carbohydrate smallest part)
AMINO-ACIDS (protein smallest part)
WATER SOLUBLE VITAMINS
MINERALS
Go through a longer way as they are not soluble in water (blood) and is more
complicated. At the end they all finish at the same place.
GLYCEROL AND FATTY ACIDS (fats smallest parts)
FAT SOLUBLE VITAMINS
Large intestine (colon)
After nutrients have been absorbed, waste products continue the way
pass to colon where water is absorbed and feases more solid (aprox 12 hours)
Collect in rectum for excretion. (all this process assisted by dietary fibre in
food)