Good Day!
Can you recall the food
that you have
taken/eaten for the past
24 hours?
Mr. R’s Digestion Song
What happens to the food
after being digested?
What system of the body
performs the process of
digestion?
Digestion of Food
 Is carried out by the organs and
substances of the digestive system.
During digestion, food is broken down to
smaller parts– a function of which is
made up of nutrients.
 These nutrients are circulated to the
different parts of the body through the
blood stream and assimilated by the cell.
Digestive System in Humans
VIDEO CLIP
What can you say about the
video?
Does our Digestive System play
a vital role in our body?
Different species of organisms have
different ways of digesting their food
In humans, digestion starts in the
mouth where food is chewed and
broken down to smaller pieces for
easier digestion.
It is called MECHANICAL DIGESTION.
Initial CHEMICAL DIGESTION also
starts in the mouth.
Different species of organisms have
different ways of digesting their food
This is carried out by ENZYMES.
These are molecules that speed up
chemical reaction. It is present in
saliva such as AMYLASE that helps
break down carbohydrates, which are
large complex molecules, into simpler
ones that can be used by the body.
DIGESTIVE
SYSTEM
Overview of Digestion
There are 2 main groups of organs in
the digestive system.
1. Alimentary Canal (nutrition)
2. Accessory Digestive Organs
Overview of Digestion
1. Alimentary Canal (nutrition)
a) Mouth
b) Pharynx
c) Esophagus
d) Stomach
e) Small intestine
f) Large intestine
Overview of Digestion
2. Accessory Digestive Organs:
a) Teeth
b) Tongue
c) Gall bladder
d) Salivary Glands
e) Liver
f) Pancreas
Overview of Digestion
3. LARYNGOPHARYNX
- Inferior to the epiglottis and posterior
to the larynx.
- The division opens into the esophagus
and larynx.
LARYNGOPHARYNX
How does “Digestion” occur?
6 step process:
1. Ingestion
2. Propulsion
Peristalsis- alternate waves of
muscular contraction and relaxation in
the primary digestive organs. The end
action is to squeeze food from one part
of the system to the next.
PERISTALSIS
How does “Digestion” occur?
3. Mechanical Digestion
-physical preparation of food for
digestion.
*Segmentation- mixing of food in the
intestines with digestive juices.
Digestive Juices
How does “Digestion” occur?
4. Chemical Digestion
- Carbohydrates, Fats, and Proteins
are broken down by enzymes.
How does “Digestion” occur?
5. Absorption
- transfer of the digested portion
of food into the blood from the
digestive canal.
How does “Digestion” occur?
6. Defecation
- removal / elimination of the waste
products from the body.