The digestive system processes food through four stages: ingestion, digestion, absorption, and egestion. It involves various organs, including the mouth, esophagus, and stomach, where food is mechanically and chemically broken down into nutrient molecules for absorption into the bloodstream. Key components like teeth, tongue, and epiglottis facilitate these processes, ensuring the safe passage of food through the digestive tract.

2. Functions of the Digestive System
Injest food
Breakdown food into nutrient molecules
Absorb molecules into the bloodstream
Rid the body of indigestible remains

3. introduction
< There are four stages to
food processing:
i. Ingestion: taking in food
z.Digestion: breaking down
food into nutrients
3•Absorption: taking in
nutrients by cells
4• egestion: removing
any
leftover
wastes Anus

4. Parts of the DigesJ
< Teeth: Grinds your
food.
< Salivary Glands:
Produce the saliva in
your mouth.
> Tongue: Helps to
push food into your
esophagus.
Fong«e
Lar9e
intestin
Anus

5. eet
o
C
u
m
t
e
h
chanically
breali down food into
small pieces. Tongue
mixes food with saliva
(contains amylase,
which helps breali
down starch).
> Epiglottis is a flap-lilte
structure at the bacli of
the throat that closes
over the trachea
preventing food from
entering it.

6. Teeth
Four types of teeth:
Incisors
Incisors
z. Canines
3• Pre —
Molars
4• Molars
Premolar
Canines
Molar

7. Biting
and
Incisor
Grinding
and
Cru,shing
Pre - Molar
Grasping
and
Tearing
Canine
and
Crushing
Molar

8. The tongue is not only one muscle.
It is a group of muscles, and it is
also what we use to taste food with.

9. Taste
The tongue con detect five basic tostes:
• bitter
• sweet:
• Sour
• Salty
• Umami
0 British Nutrition Foundation

10. The Human Die
' The tongue pushes food around
until it forms a ball called a bolus.
The bolus is passed to the pharynx
(throat) and the epiglottis malxes
sure the bolus passes into the
esophagus and not down the
windpipe!
Hyt›tij›haryux

12. The Esophagus
• The muscular tube through which
food passes from the mouth to the
stomach
• As you chew, your tongue helps
mould your food into a mass called
a bolus that then gets pushed to
the back of your mouth
• When yo» swallow, the bolus
enters the top of the esophagus
• The opening of the esophagus lies
next ’to the opening of your
windpipe
• To prevent food from going down
the wrong tube, the opening of
your trachea is closed by the
epiglottis (valve) when you
swallow
|3]

13. Muscular contractions
of digestive tract
(pen'stalsis)
The bolus passing d
o
w
n
the esophagus by
peristalsis.
’
- Peristalsis is a wave of
muscular contractions
that push the bolus
down towards the
stomach.

14. „. ,
’" To enter the stomach,
the bolus must pass
through the esophageal
sphincter, a tight muscle
that l<eeps stomach acid
out of the esophagus.