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Can you sort out the statements into
True and False?
1
Carbohydrates, proteins and fats are all made up of carbon,
hydrogen, nitrogen and oxygen.
2
Fats are made up of smaller units called amino acids
3
Starch is a large carbohydrate molecule
4
Proteins are made up of one or more glucose molecules
5
Starch molecules can be broken down by amylase.
6
Proteins are important for the growth and repair of cells
Parts of The Alimentary Canal
The alimentary canal (or gut) is the tube
within the body through which food passes
and is processed in various ways
o mouth
o oesophagus
o stomach
o small intestine
o large intestine
o anus
Human digestive system
mouth
salivary glands
oesophagus
liver
stomach
pancreas
large intestine
small intestine
anus
Enzymes
They are special proteins that behave as catalysts,
i.e., they accelerate each and every chemical
reaction in your body; otherwise, those chemical
reactions wouldn't take place, or would do at a very
slow pace. Enzymes are very specific and each
one can catalise only one chemical reaction: for
instance, the only thing that salivary amylase can
do is breaking the starch into maltose.
Role of the Mouth
Teeth assist the
mechanical breakdown
of food
Saliva is mixed with
food during chewing
Saliva contains the
enzyme amylase which
starts the digestion of
food
Salivary gland
Salivary gland
Salivary gland
Saliva contains mucus
that keeps the mouth
moist and lubricates
food for easier
swallowing
Muscles of the Alimentary Canal

Food has to be kept moving along the
alimentary canal whilst being mixed with
various juices

These actions are brought about by
muscles in the walls of the canal over
which a person has little or no conscious
control
Peristalsis
The squeezing action of muscles that is
used to move food along the
alimentary canal
• Peristalsis-1
Peri1.spl
• Peristalsis-2
Digestive Enzymes
What do the following enzymes
breakdown?
 What do they break the large moleculs
down into?

Amlyases
 Lipases
 Proteases

Sites of production of main digestive
juices
Site of digestive juice
production
Mouth
Main digestive juice
produced
Saliva
Stomach
Gastric juice
Liver
Pancreas
Bile (breaks down big fat
droplets into little fat
droplets
Pancreatic juice
Small Intestine
Intestinal juice
Digestion and Digestive Juices
Saliva
GASTRIC JUICE
Bile
PANCREATIC
JUICE
INTESTINAL
JUICE
Digestion and Digestive Juices
SALIVA
•Salivary amylase
•Mucus
Bile
GASTRIC JUICE
•Hydrochloric acid
•Pepsin (protease)
•Rennin
PANCREATIC
JUICE
•Mucus
•Pancreatic lipase
•Trypsin
INTESTINAL JUICE
Proteases, Lipases, amylase
In the Mouth…
Salivary amylase
Starch

maltose
Broken down into glucose later by other
amylases
Types of Teeth
1.Incisor
2. Canine
3. Premolar
4. Molar
Tongue

The tongue is a muscle on the floor of the mouth that manipulates food for
chewing and swallowing (deglutition). It is the primary organ of taste, as
much of the upper surface of the tongue is covered in papillae and taste
buds.
Taste regions of tongue
Taste buds of tongue
Swallowing of bolus
Section of stomach
In the stomach
Protein
pepsin
peptides
Broken down into amino acids later by
other proteases
Chyme

The fluid food mass that is produced in
the stomach when the bolus undergoes
a second digestive stage.
Functions of liver
There are many functions of the liver. Some of the most important
are:
1.
The production of bile
2.
Detoxifying the body, i.e. breaking down alcohol and drugs
3.
Breaking down excess amino acids to form urea
4.
Converting glucose to glycogen for storage
5.
Converting excess carbohydrates to fats
6.
Storing vitamins
7.
Storing minerals such as Iron, Copper, and Zinc.
8.
Making plasma proteins such as fibrinogen which is used
in blood clotting
9.
Making cholesterol which is used to form many hormones
10.
Producing heat for the blood and body

Liver Facts
• Weighs about 1 pound.
• Carries out 1000s of functions per day.
• Effects the emotions.
• Cleanses the blood.
• Helps regulate blood sugar.
• Metabolizes fats.
• Synthesizes vitamin A.
• Breaks down toxic substances.
• Stores iron for the body.
• Stores glycogen (converted glucose).
• Metabolizes carbohydrates.
• Metabolizes proteins.
Position of Liver
Bile

One of the five digestive juices. It is
produced by the liver, stored in the gallbladder, and it is greenish. It is necessary
mostly not to carry digestive enzymes to
the duodenum, but to transport bile salts to
the duodenum. The bile salts are
necessary to help the lipids to "dissolve" in
the chyle, forming small droplets, easy to
be attacked by the lipases. This process is
called emulsification.
Small Intestine
Duodenum
Gall
bladder
Bile
Hepatopancreatic duct
Jejunum
Intestinal glands
Composition of Bile
Constituent
pH
Na+
K+
Ca2+
ClHCO3Phosphorus
Bile acids
fatty acids
Bilirubin
Phospholipids
Cholesterol
Proteins
In the pancreas….
Fats
Pancreatic lipase
fatty acids and glycerol
After all the digestive enzymes have
done their work…

Glucose

Amino acids

Fatty acids

Glycerol
Finish the sentence….

Something new I learnt today was…..

Something I found difficult to understand
was…

The thing I need to revise from today’s
lesson is…