Zusammenfassung der Ressource
Digestive System
- Mouth
- adds saliva, breaks food into small pieces
- Oesophagus
- squeezes food towards stomach,
connects mouth and stomach
- Stomach
- Churns food up with acid, adds
protein-digesting enzymes
- Small intestine
- contains digestive enzymes made by
the pancreas, allows nutrients to pass
through the walls into the blood
- Pancreas
- makes digestive enzymes, secretes
enzymes into small intestine
- Large intestine
- water passes through it's walls into
the blood, undigested food passes
along this tube
- Liver
- makes bile, processes nutrients
- Gall bladder
- releases bile into small
intestine when needed,
stored bile made by liver
- Chemical and
mechanical
processes
- enzymes speed up chemical
reactions
- Carbohydrases
- found in mouth, turns starch into
glucose
- e.g. amylase
- Proteases
- found in stomach, turns
protein into amino acids
- e.g. pepsin
- Lipases
- found in s. intestine,
turns fats and oils
into fatty acids and
glycerol
- e.g. Lipase
- Bile
- strongly alkaline, neutralises stomach
acid, ensures optimum conditions for
enzymes in s.intestine to work
- contains salts that break down
fats and oils into small droplets
- Emulsification
- increases surface area of fats and
oils to speed up their digestion
- Absorption in the small intestine
- inside wall is thin with
large surface area
- absorption happens
quickly and efficiently
- lined with villi
- increases surface area, more
nutrients absorb faster
- increases rate of diffusion
- lacteals
- take away fat from s.i. to
ensure there's a difference in
concentration
- increases rate of diffusion
- blood capillaries
- take blood to different
vessel, ensures there's a
concentration gradient
- increases rate of diffusion
- One cell thick
- less
distance for
nutrients to
travel
- absorption is quicker
- Functional foods
- have health-promoting
benefits more than basic
nutritional value
- probiotics
- contain bacteria to maintain
healthy digestive system
- Bifidobacteria
- prebiotics
- contain added sugars that "feed"
bacteria in alimentary canal
- Oligosaccharides
- Plant stanol esters
- come from plant stanols
- found naturally in food such
as wheat and maize
- clinically proven to reduce absorption
of cholesterol