The human digestive system breaks down food through mechanical and chemical digestion. Mechanical digestion is the physical breakdown of food through chewing and churning. Chemical digestion uses enzymes in the digestive juices secreted by organs like the liver, pancreas, and salivary glands to further break down food. The main parts of the digestive system are the mouth, esophagus, stomach, small intestine, and large intestine. Food is broken down and nutrients are absorbed through these parts as food moves through peristalsis.

2. Introduction
• The Human
digestive system is a
complex process
that consist of
breaking down large
organic masses into
smaller particles
that the body can
use as a fuel.

3. Types of Digestion
• Mechanical digestion:
• The physical
breakdown of food
through mastication
(chewing), mixing with
saliva by tongue action,
churning in stomach.

4. • Chemical digestion:
The chemical
breakdown of food
because of substances
secreted by accessory
organs.It is
accomplished by
enzymes in digestive
juices.

5. Parts of Digestive System
Main Parts Accessory Parts
• Mouth • Liver
• Esophagus • Pancreas
• Stomach • Gall bladder
• Small Intestine • Salivary glands
• Large Intestine

6. Mouth:
The mouth is
the beginning of the
digestive system, and,
in fact, digestion starts
here before you even
take the first bite of a
meal.

7. There are two major processes which take place
Mastication:
- Breaks down large food molecules
- Increases surface area of food particles
Secretion of Saliva:
- Contains salivary amyles (ptylain) that digest starts to
maltose
- It lubricants and moistens food
- Provides alkaline medium

8. Esophagus:
- It is a mucus muscular
membrane lined tube
- Muscles move the food to
the stomach through a wave-
like motion refferred to as“
Peristalsis”

9. Peristalsis:
It is an involuntary
process of muscular
contraction forcing the
food (bolus) down to the
stomach

10. Stomach:
The stomach is hollow,
muscular holding pouch for
food. The stomach has 3
regions:
• The fundus
• The body
• The pylorus

11. The food enters this part of stomach from the
esophagus. The esophageal (cardiac) sphincter,
a circle of muscular tissue, surrounds the place
where the esophagus enters the stomach and
keeps food from going back up the esophagus
after it has entered the stomach.

12. Functions of Stomach:
 churns, mixes and stores food
 site of food breakdown using HCL and Pepsin
 chemical breakdown of protein begins

13. • Small Intestine:
The small intestine is the
body’s major digestive organ.
It is a muscular tube extends
approximately 20 feet.
Nutrients are absorbed in
small intestine through villi
(which increases surface area)
into the blood stream.

14. Parts of Small Intestine:
 Duodenum
 Jejunum
 Ileum

15. • Large Intestine:
The distal portion of the
intestine, about 5 feet
long, extending from its
junction with the small
intestine to the anus and
comprising the cecum,
colon, rectum, and anal
canal.