Download the digestive system

THE DIGESTIVE
SYSTEM
J.KEMP
TPJ3M
THE DIGESTIVE
SYSTEM
The digestive system
breaks down food:
1. physically
2. chemically
so it can be absorbed
for use by the cells.

The system also
eliminates solid
waste from the
body.
THE DIGESTIVE
SYSTEM
The digestive system is made up of the:
1. Alimentary canal
2. Accessory organs
ALIMENTARY CANAL
The alimentary canal is a long tube (about 30 feet
stretched out end to end) that extends from the
mouth to the anus.
 It digests food by breaking it down into smaller
fragments and absorbs the fragments into the
bloodstream
 Food is moved along the digestive system by
peristalsis (involuntary muscle contractions)
THE DIGESTIVE
SYSTEM
The components of the alimentary canal
are the:
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
THE DIGESTIVE
SYSTEM
THE MOUTH
 Food enters the
digestive tract
through the mouth
 It is then mixed with
saliva and chewed
 The tongue
continuously mixes the
food with saliva and
initiates swallowing
THE DIGESTIVE
SYSTEM
THE PHARYNX
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From the mouth, the food
passes into the pharynx
The pharynx has 2 muscular
layers that contract and
propel food into the
esophagus.
THE ESOPHAGUS
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Runs from the pharynx
through the diaphragm to
the stomach.
It is a passageway to the
stomach
THE DIGESTIVE
SYSTEM
THE STOMACH
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The C shaped stomach is on the left side of the abd.
cavity, hidden by the liver and diaphragm.
It is approx 10 inches long but its diameter depends on
how much food is in it
When it is full it can hold 4 litres of food.
The stomach acts like a temporary storage container
for food and as a site to break food down physically and
chemically.


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Physically, by churning, mixing and turning the food
Chemically, by secreting gastric juices
After food is processed it is called chyme
It then enters the small intestine
THE DIGESTIVE
SYSTEM
THE SMALL INTESTINE
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1.
2.
3.

The small intestine is the body’s major digestive
organ and is approx. 20 feet long
It has 3 sections:
The duodenum – adds more digestive juices,
including bile (greenish liquid produced by the liver
and stored in the gallbladder)
The jejunum – absorption takes place here
The Ileum – absorption takes place here
The small intestine is lined with villi. Villi absorb
the digested food into the capillaries
THE DIGESTIVE
SYSTEM
THE LARGE INTESTINE

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1.
2.
3.
4.
Larger in diametre but shorter in length (approx 5 feet)
than the small intestine
Also called the colon
The large intestine also contains the appendix, rectum, and
anus
Its function is to absorb water from undigested food and
eliminate feces
The large intestine is subdivided into 4 sections
The ascending colon
The transverse colon
The descending colon
The sigmoid colon
THE DIGESTIVE
SYSTEM
The accessory organs are:
 Teeth
 Tongue
 Salivary glands
 Liver
 Gallbladder
 Pancreas
THE DIGESTIVE
SYSTEM



Give the definition and/or function for each
of the accessory organs using the textbook.
Use pg’s 215-216 as well as the texbook’s
index
Describe/summarize how food moves
through the digestive system
THE DIGESTIVE
SYSTEM

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Digestion begins at the mouth
(receives food and prepares it for
digestion).
Using chewing, the teeth cut, chop
and grind food for digestion and
swallowing.
The tongue helps with chewing and
swallowing.
Salivary glands create saliva, which
moistens food for easier swallowing
and begins to digest food.
During swallowing, the tongue pushes
the food to the pharynx (throat).
THE DIGESTIVE
SYSTEM

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This is a muscular tube and as
it contracts, the food is
pushed into the esophagus.
The esophagus is another
muscular tube which extends
from the pharynx to the
stomach.
Involuntary muscle
contractions called
peristalsis moves the food
down the esophagus into the
stomach.
THE DIGESTIVE
SYSTEM

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The stomach is a pouch like sac which stirs and
churns food to break it up.
The stomach secretes gastric juices to aid in this
process until it becomes chyme (a semiliquid
substance).
Via peristalsis, the chyme is pushed from the stomach
into the small intestine.
The small intestine is about 6 metres long and has 3
parts. The first part is the duodenum.
When chyme gets to the duodenum, more gastric
juices are added. One of these juices is called bile.
Bile is a greenish liquid produced by the liver and
stored in the gallbladder. Juices from the pancreas
are also added to the chyme.
THE DIGESTIVE
SYSTEM
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All of these digestive juices break down food
so it can be absorbed.
Next, peristalsis moves the chyme to the
jejunum and the ileum. Tiny villi line the
small intestine. They absorb digested food
into the capillaries.
Most of absorption takes place in the
jejunum and ileum.
Some chyme remains undigested and is
absorbed by the colon or large intestine..
THE DIGESTIVE
SYSTEM
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The remaining semi solid material is called
feces.
Feces consists of a small amount of water, solid
wastes and some mucus and microorganisms.
Feces passes through the colon into the rectum
and finally through the anus.
The process of excreting feces is called
defecation.
Feces that has been excreted is called stool