2. The series of the tube-like organs that
convert our meals into body fuels
The breakdown of large insoluble
molecules into smaller soluble molecules
which can pass through the wall of the gut
into the blood.
DIGESTIVE SYSTEM
3. DIGESTIVE ENZYMES
Enzymes helps in the breakdown of food, in a
process called CHEMICAL DIGESTIONS.
Food contains carbohydrates, proteins, and
lipids, so a wide range of enzymes is needed
a. Amalyses
b. Proteases
c. Lipases
5. • Food is crushed and ground up by
teeth
• The salivary gland make saliva
which makes the food moist and
easy for swallowing.
• Amylase enzyme breaks the
carbohydrates starch down into
glucose .
MOUTH
6. AMYLASE
Amylase is defined as a digestive enzyme that
breaks starch into small carbohydrate
molecules. This enzyme is produced in two
areas. Firstly, salivary glands in our mouth
generate salivary amylase that starts the
process of digestion by breaking down starch
and converting it into maltose and smaller
carbohydrate.
starch amylase maltose
7. WHAT IS PERISTALSIS
Peristalsis is the contraction and
relaxation of the circular muscle in
the wall of the gut
When the muscle contracts at the
top of food, the food is pushed
down.
When it relaxes, the food drops
down.
8. STOMACH
• Stomach muscle contract and relax to
mechanically break down food
• They also mix the food up with the
hydrochloric acid and gastric juice contains
proteases enzyme PEPSIN to digest
proteins to amino acid.
9. GASTRIC JUICE
Gastric juice is produced by gastric glands in the stomach wall.
It contains :
• mucus
• hydrochloric acid
• the inactive enzyme precursor e.g pepsinogen
Some digestive enzymes are secreted as inactive
precursors because, in their active state, they would be
potentially very harmful to the exocrine gland cells that
produce and secrete them
10. • Pepsinogen is activated by the hydrochloric
acid,which converts it into pepsin which is an
endopeptidose.
• Pepsin convert proteins into peptides
PEPSIN
pepsin
peptide
s
protien
11. • The major digestive organ
• Neutralize acid from stomach,add
digestive enzymes and bile,break proteins,
carbohydrates and lipids to obserbable
materials
• Site of nutrient absorption into the blood
• 95% of food absorbed here
• Three parts : duodenum, jejunum, ileum
SMALL INTESTINE
12.
13. • Pancreatic juice is produced by the
exocrine glands in the pancreas
• It contains:
- bicarbonate ions (alkaline)
- enzymes, including pancreatic amylase
and pancreatic lipase, endopeptidases and
exopeptidases
- the inactive enzyme precursor-
trypsinogen, chymotrypsinogen
FROM PANCREAS
14. • Pancreatic amylase carries out the
same reaction as salivary amylase.
PANCREATIC AMYLASE
Starch Maltose
Amylase
15. • Pancreatic lipase breaks down
triglycerides into glycerol and fatty
acids.
PANCREATIC LIPASE
triglycerides glycerol +fatty acids
lipase
16. SPECIAL PROBLEMS OF LIPIDS
The breakdown of lipids poses special problems,because lipids are
insoluble in the aqueous environment of the digestive tract.
• As food travels through the digestive tract , the lipids within
them melt and coalesce into larger droplets
• Lipase is a water soluble, so is unable to enter the lipids
droplets and would only be able to breakdown the lipids on the
surface of the droplets.
• Food does not remain in the digestive tract long enough for
lipase to be able to be able to completely digest the lipids in
this manner.
17. • Bile is a fluid that is made and released
by the liver and stored in the gallbladder.
• It has 2 primary functions: To carry away
waste. To break down fats during
digestion.
• When digestion of fatty food occurring,
bile is introduced into duodenum from
gallbladder
BILE
18. • Bile molecules have a
hydrophobic end and a
hydrophilic end, so are able to
interact with both the lipids and
the water, causing the lipids to
break up into smaller droplets.
This process is called
Emulsification
• This speeds up the digestion of
the lipids in the small intestine .
HOW DOES BILE WORK ?
19. • Trypsinegen is activated by an enzyme
called enteropeptidase, which is secreted by
the lining of the small intestine.
Enteropeptidase converts trypsinogen to
trypsin.
• Trypsin continues the breakdown of protiens.
TRYPSIN
peptides smaller peptides
trypsin
20. • The juice contains;
• Maltase which converts maltose
to glucose.
• Exopeptidase which makes short
polypeptides
• Dipeptidase which makes double
acids to single ones
FROM DUODENAL GLANDS
21. • The inner linning of ileum contain
very small finger-like bumps
called "villi".
• The presence of these tiny bumps
on the inside of the small intestine
means that the surface area is
much longer than if the lining
were just a flat surface.
• Absorption is through diffusion,
facillitated diffusion and active
transport .
ILEUM
22. • All the food which cannot be
digested ends up in the large
intestine.It enters into the colon
where most of the water is
reabsorbed into the blood.
• The indigestible remains form a
semi solid faeces which is stored
in the rectum.Eventually it is pass
out the anus
LARGE INTESTINE
