Transcript Digestive System

Digestive
System
Knife
Food Processor
Garbage Disposal
Which organ of the digestive system does
each picture represent?
• The function of the digestive system is to
break down food so that it can be used
as energy in your body.
• The system consists of a series of
complex organs and glands (which
excrete enzymes) that break down food
into small usable particles.
Mechanical Digestion:
-food is broken down
mechanically, with
movement
Ex: Teeth
Chemical Digestion:
-food is broken down
with a chemical or
enzyme
Ex: Saliva
• Peristalsis- series of involuntary smooth
muscle contractions along the walls of the
digestive tract.
• Moves food through the digestive system.
Organs Involved:
1. Mouth
2. Esophagus (A)
3. Stomach (C)
4. Small Intestine (E)
5. Large Intestine (F)
•
•
•
•
Appendix
Pancreas (D)
Liver (K)
Gall Bladder (J)
Digestion begins in the
mouth.
As you chew your food,
two processes are
occurring:
1. TEETH- your teeth
begin mechanical
digestion by breaking
down food into smaller
pieces.
2. SALIVA- this enzyme
helps break down
starches chemically
1
The mouth completes
both mechanical and
chemical digestion!
As you swallow, the food must
pass several structures:
• Pharynx- Back of the throat
opens into esophagus
• Epiglottis- flap of tissue that
keeps chewed food from
going down the trachea to the
lungs. As you swallow, the
epiglottis flops closed.
• Larynx- Vocal cords
• The esophagus is a
long tube that runs
from the mouth to the
stomach.
• After being chewed
and swallowed, the
food ball (bolus)
enters the esophagus.
2
• The food is deposited
in the Stomach.
• The stomach is a
large, sac-like organ
made of muscle.
3
• The stomach churns
food AND bathes it in
gastric juice (acidic).
• Food remains in the
stomach for 2-4
hours, turning into a
thin liquid soup called
chyme.
3
The stomach
completes both
mechanical and
chemical digestion!
• The liquid chyme is
the transported to the
small intestine.
• SI is a narrow
muscular tube about 6
meters long, lined with
villi.
4
• Bile and other enzymes
are injected into the
Small Intestine to
further break down the
food.
Is this mechanical
or chemical
digestion?
4
Food remains in the SI
for 3-5 hours
Don’t
forget the
Bacteria!
• Villi- finger-like extensions
that absorb nutrients
• Villus expand surface
area of SI.
4
• The function of the
SI is to absorb all
usable nutrients.
• The villi are covered
with capillaries
which pick up the
nutrients for ALL
cells in the body.
4
What system works
with Digestive?
Blood
vessels pick
up nutrients
from SI
• Anything (liquid or
solid) that is not
absorbed by the SI is
sent to the Large
Intestine.
• The colon absorbs
most excess liquids.
5
Don’t
forget the
Bacteria!
• After about 18-24 hours…
• The END process- solid
waste (feces) is stored in
the rectum until it is
excreted through the
anus.
5
• The digestive system is also part of the
Excretory system!
Your meal’s entire journey through the Digestive
System has taken between 24 and 33 hours.
Many organs play a role in the digestion of
foods but never come in contact with
food, we call these accessory organs.
Three such organs are:
– Liver
– Gall Bladder
– Pancreas
• Liver- large organ located above and in
front of the stomach.
• It filters toxins from the blood and makes
bile (breaks down fats).
• Gall Bladder- small, sac-like organ located
near the SI.
• It stores and releases bile into the small
intestine.
• Pancreas- an enzyme producing organ
located below the stomach and above the
intestines.
• Enzymes from the pancreas aid in
digestion of carbohydrates, fats and
proteins in the small intestine.