4. The Mouth
• Teeth break down
food into small pieces
• Salivary glands make
saliva.
• Chewed food gets
mixed with saliva
• Saliva contains
enzymes, which start
to digest starch to
sugar
5. Teeth
• Four types of
teeth:
1. Incisors
2. Canines
3. Pre – Molars
4. Molars
Incisors
Canines
Premolar
Molar
8. The Oesphagus
• Passes food down to
your stomach
• The oesophagus has
circular muscles in its
wall
• These muscles
contract and squeeze
in behind the food to
push it along
Oesphagus 25 cm
long
9. The Stomach
• Muscular bag that holds
2 litres of food
• Secretes hydrochloric
acid
• Makes digestive juices
• Muscular walls churn
the food making sure
it’s all mixed
• After 2-3 hours
churning it’s a runny
liquid
10. The Liver
• After food has been
absorbed into the
blood, the food is
taken to the liver
• The liver processes
some of it, before it
goes any further
• The food dissolved in
plasma is the taken to
other parts of the
body
11. Pancreas
• Leaf – like structure
• Produces digestive
enzymes
e.g. amylase
• Passed in Small
Intestine and helps in
the digestion of food
• Helps control blood
sugar
12. The Small Intestine
• Actually 6 m long!
• Plays important roles
in digestion and
absorption
• Two important liquids
are added here:
Pancreatic juices
Bile
• 90% of food is
digested and
absorbed here!
13. The Large Intestine
• Shorter but wider than
small intestine
• Absorbs water from
food
• Passes water into the
blood
• Mainly fibre, dead
cell, bacteria and
water reach here!
14. OB8 – Investigate the action of amylase
on starch; identify the substrate, product
and enzyme
15. An enzyme is a biological
catalyst
– speeds up chemical reactions
inside cells
17. Enzymes
• Proteins found in every
cell of the body
• Digestive enzymes –
involved in breaking
down food
– Amylase in Saliva
• Amylase breaks starch
down into Maltose
• http://subscription.echalk.
co.uk/index.htm
20. OB8 - Investigate the Action of
Amylase on Starch
Starch Soln.
+ Amylase
Starch Soln.
+ Water
Tube B
Tube A
Starch not
broken down
Starch broken
down
Iodine
21. To Show that Amylase Breaks
Starch into Glucose
Starch Soln. +
Amylase
Starch Soln.
+ Water
Tube C
Tube D
No Glucose
Present
Glucose Present
Benedicts Solution
24. Facts for the Curious!
• What is added to the
food each day as it
passes through the
gut…….
• In mouth: saliva = 1 litre
• In stomach: acid &
enzymes = 1 litre
• In intestines: bile from
liver = ¾ litre,
pancreatic enxymes =
¾ litre, intestinal
enymes = ½ litre
• Total: 4 litres!!
25. Facts for the Curious
• 70 year olds only
produce about half
the amount of
enzymes that they
produced when they
were 20!
