Transcript Digestion

Digestive System and Enzymes
What we are going to learn in this section
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Digestion (explain)
Chemical and physical digestion
Enzymes + examples
Substrate and product + examples
Experiment, the action of amylase on
starch.
Nutrition stages EDAF
 Eating, Digestion, Absorption, Faeces
(explain)
Digestive System and Enzymes
What we are going to learn in this section
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Parts of digestive system and
functions
Mouth (what happens) Teeth (4 types
and function)
 Oesophagus
 Stomach (3 things it does)
 Small intestine (2 things) and Role of
liver and pancreas.
 Large intestine (2 things)
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The digestive system
The whole point of digestion is to break down our food so
that we can get the bits we need from it…
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The Digestive System
Stages in Nutrition (feeding)
1)Ingestion (eating) – food taken into the mouth
2)Digestion – Food is broken down in smaller soluble
molecules.
3)Absorption – the digested food is taken into the
bloodstream and carried to the cells where it is used.
4)Egestion – getting rid of undigested food as faeces.
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Enzymes and cells
Enzymes catalyze the thousands of reactions that need to
take place in order to maintain life. What are some of
these reactions?
 digestion
 respiration
 photosynthesis
(plants and some bacteria)
 protein synthesis (making).
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What are digestive enzymes?
Enzymes are biological catalysts
Digestive enzymes are produced by specialized cells in
different parts of the digestive system
Here the enzymes help
to break down large food
molecules into smaller
molecules that are more
easily absorbed.
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You need to know
A catalyst is chemical that changes the speed of a
chemical reaction, but is not used up in the reaction
Substrate
enzyme
product
starch
amylase
maltose
The substance the enzyme acts on is called the
substrate
The substance formed as a result of the reaction is
called the product.
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Where are the
Enzymes made?
Amylase enzymes
-> mouth
->pancreas
Lipase enzyme
-> small intestine
-> pancreas
-> Small intestine
Protease enzymes
->Stomach
->pancreases
->small intestine
Web address
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Digestion - The Mouth
Enzymes in saliva (amylase) break down starch into
Maltose sugar.
The teeth physically break the food into smaller pieces
They crush and cut the food
we eat.
1)Incisors cut an bite the
food
2)Canines tear the food.
3)Molars and premolars
crush and grind the food.
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Digestion in the Stomach
The stomach is involved in three processes.
Produces enzymes to break
down proteins.
Stomach muscle churns and
mixes the food.
Hydrochloric acid produced that
kills bacteria and other germs.
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Digestion - The small intestine
In the small intestine:
Enzymes released from the
pancreas and bile from the
liver digest the food from
the stomach.
The useful food is
absorbed into the blood
stream.
The leftovers, water and
undigested food is pushed
into the large intestine.
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The Liver
Produces bile to help
digest fats.
Breaks down harmful
substances.
The Pancreas
Produces the enzymes
to digest the food.
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The small intestine
This is where the “small parts” are absorbed into our blood
stream…
Everything else
passes into the
large intestine
Glucose gets
absorbed into
the blood
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Fats
Fats are digested in two stages:
• Firstly bile (released by the gall bladder) allows the fat to “mix”
with water by breaking the fat up into smaller droplets. This is
called emulsification.
Bile
• Secondly, an enzyme called Lipase breaks the fats down into the
smaller fatty acid molecules and glycerol.
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Lipase
Fatty
Fat
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Glycerol
acid
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Bile and the liver
Bile is a chemical produced in the
liver and stored in the gall
bladder. It has 2 functions:
1) It neutralises stomach acid
and produces alkaline
conditions for enzymes to
work in
2) It emulsifies (“breaks down”
fats:
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Fat
globules
Fat
droplets
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Digestion – The large intestine
Large intestine:
Takes water back into the
bloodstream.
Bacteria live there that make vitamin B
for us
The leftover undigested food called
the faeces is pushed into the rectum
and stored there. It is released from the
body via the anus.
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