It discuss about what is digestion, five stages of digestive system - ingestion, digestion, absorption, assimilation and egestion. it also discuss about mouth, tongue, teeth, alimentalry canal - pharanyx, oesophagus, stomach, small intestine, large intestine, liver, pancrease etc.,

1. DIGESTIVE SYSTEM
DR. C. BEULAH JAYARANI
M.Sc., M.A, M.Ed, M.Phil (Edn), M.Phil (ZOO), NET, Ph.D
ASST. PROFESSOR,
LOYOLA COLLEGE OF EDUCATION, CHENNAI - 34

2. • Parts of the body concerned with the
digestion of food form the digestive
system.
• Digestive system consist of two sets of
organs.
• 1) Gastro intestinal tract : it is a passage
starting from the mouth and ending with
the anus.
• 2) Digestive glands : glands associated
with the alimentary canal.

3. • The food we eat contain not only simple substances like
vitamins and minerals but also complex substance like
carbohydrates, proteins and fats.
• The body cannot use these complex substance unless they
are converted into simple substances.
• The breakdown of complex substances such as
carbohydrates, proteins and fats into simpler
substance is known as digestion.

4. Nutrition
process
Ingestion Digestion Absorption
Assimilation Ingestion

5. • Parts of the body concerned with
digestion is called digestive
system.
DIGESTIVE SYSTEM

6. ORGANS OF DIGESTIVE SYSTEM
• Alimentary canal- it is the passage of
food starting from the mouth and
ends with anus.
• Mouth, buccal cavity, pharynx,
oesophagus, stomach, small
intestine, large intestine & anus

7. MOUTH
• The buccal cavity is a large space
bound above by palate below by
throat and sides by the jaws.
• Jaws and teeth
• Salivary glands
• Tongue

8. TEETH
holding , crushing, grinding ,
cutting.
Diphyodont
 Milk teeth (temporary teeth)
 Permanent teeth
(Theocodont)
• Heterodont

10. each
half of a jaw
• The types of teeth are denoted
as incisors, canine , premolar
and molar.

11. saliva into mouth cavity
Parotid
gland, sublingual gland,
submandibular gland

12. PAROTID GLANDS Large
Below the ears
SUBMAXILLARY
GLAND
Irregular in shape
Found below the
jaw
SUBLINGUAL
GLAND
Small
Found base of
the tongue
1. Ptyalin – Amylase – enzyme
2. Bicarbonate – salt
3. Mucus
4. Lysozyme - enzyme

13. TONGUE
• Tongue is a muscular , sensory
organ which helps in mixing the food
with the saliva.
bolus which is
rolled by the tongue and passed
through pharynx into the
oesophagus by swallowing
epiglottis
closes and prevents the food from
entering into trachea.

14. It is a membrane lined
cavity behind the nose and
mouth, connecting them to
the oesophagus.
pathway for
the movement of food from
mouth to oesophagus.

15. • Oesophagus is a muscular –
membranous canal about 22 cm in
length.
• It conducts food from pharynx to the
stomach by
produced by the
rhythmic contraction and relaxation
of the muscular walls of alimentary
canal.

16. ‘J’ Shaped structure, Muscular organ
Gastric juices contain mucus, HCl and
enzymes such as pepsin and renin in
infants
Inactive pepsinogen  Active Pepsin
Hydrochloric acid kills bacteria
Action of gastric juices  Chyme 
Pylorus

17. • Duodenum C shaped and receives bile duct
from liver and pancreatic duct from pancreas.
• Jejenum Secretes intestinal juice that contains
enzymes like sucrase, maltase, lactase and
lipase.
• Ileum Longest part of small intestine that
contains finger like projections called villi (4
million in number)

18. Reddish brown in color
Two main lobes
Bile salts and bile pigments
Emulsification of fats

19. • Leaf shaped gland
• Acts as both exocrine
and endocrine gland
3 enzymes
–lipase, trypsin and
amylase
ISLETS OF LANGERHANS
alpha and beta
cells.
• Secretes intestinal juice

20. • Unabsorbed and undigested food passes
through large intestine
• 1.CAECUM
• 2.COLON ascending, transverse and
descending colon
• 3.RECTUM

21. INGESTION
• The first step to obtaining
nutrition is ingestion,
a process where food is taken
in through the mouth and
broken down by teeth and
saliva.
• Organs involved in ingestions are
Teeth, tongue, salivary glands,
epiglottis, oesophagus

22. DIGESTION
Digestion is the complex process of
turning the food we eat into nutrients,
which the body uses for energy, growth
and cell repair needed to survive.
The digestion process also involves
creating waste to be eliminated
Digestion begins in the mouth. The
food is ground up by the teeth and
moistened with saliva to make it easy
to swallow.
 Saliva also has a special chemical,
called an enzyme,
which starts breaking down
carbohydrates into sugars

23. AbSORpTION
• Digested food molecules
are absorbed in the small intestine.
• This means that they pass through
the wall of the small intestine and
into our bloodstream.
• Once there, the digested food
molecules are carried around
the body to where they are needed
• The primary function of the small
intestine is the absorption of
nutrients and minerals found in
food.

24. ASSIMIlATION
• The movement of digested food
molecules into the cells of the
body where they are used.
• For example: glucose is used in
respiration to provide energy,
amino acids are used to build
new proteins.

25. EGESTION
• Undigested food and assimilated
food is thrown out from the body
through anal aperture as FAECAL
MATTER

26. REFERENCE
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