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The Digestive System
By:
Melissa Bethke
Amani Anis-hanna
Erin Plant
Function
 Makes food into molecules so
that it’s small enough to be
absorbed and utilized by the
different cells in the body.
 The body uses those
molecules for building
nourishing cells, repairing,
and providing the energy
needed.
 If the body does not need the
particles that have been
broken down through
digestion, then the body
creates the waste that is then
removed.
Organs and Facts
Organs include:
 Liver
 Pancreas
 Stomach
 Caecum
 Small and Large Intestines
 Some animals eat and
excrete out the same hole.
 Roundworms can invade
your body.
 Sponges have no digestive
system.
 Starfish push its stomach
through its mouth.
How it Works in Animals
 They take in their
food as large and
complex molecules
that need to be
broken down,
through the
digestive system
into small molecules
that can be
transferred to every
cell in the body.
How it Works in Detail
2 phases – mechanical and chemical
 Mechanical: teeth or other structures work to
break down their food into smaller pieces.
 Chemical: enzymes break down those pieces
into even smaller molecules so that it can be
absorbed and spread throughout the body.
It then travels through the digestive tract which
then exits the body.
Digestive Opening
 Different phyla have different numbers of openings.
 This depends on how they excrete the food.
Perifera Coelenterata Platyhelminthes Nematoda Annelida
1
1
1
2
2
Mullusca
2
Porifera
 Take in food
through their
pores.
 They filter their
food by microorganisms from
the water.
 They have no
digestive system.
* includes: sponges
Cnidarians
They use their
tentacles to travel
their food through
their mouth and
into their gastro
vascular cavity.
* includes: jellyfish,
sea anemones
Flatworms
 A flatworm has a combination digestive/excretory
system.
 It takes food in and gets rid of wastes through the same
opening.
 The food goes through the mouth to the esophagus.
 The muscles use a wavelike fashion to force food down
the length of the intestine.
 Undigested food leaves out the mouth.
Roundworms




Digestive system runs the length of the body.
Many live off other animals and plants.
Mouth opens into the muscular pharynx.
Muscular pharynx acts as a vacuum to bring food to the
intestine.
 It goes down the intestine and is excreted.
Mollusks
 There are different kinds of mollusks.
 Valves=one shell=snails
 Bivalves=two shells=clams and oysters
 Head-foot Mollusks=squid and octopus
Mollusks






The mouth of a mollusk is a radula
Looks like a tongue covered with tooth-like structures
Rubs radula against plants to break off parts.
Mollusks have 2 digestive openings.
In some mollusks such as bivalves the radula is absent
After the radula the food then goes to the digestive gland
then the intestine
Anthropoda
Anthropoda have a
complete digestive
system
The mid-gut
section of the
typical Anthropoda
is the main site for
enzyme production
Echinodermata
 Most members of the
Echinodermata phylum
have hard plates that
retract and grasp like
teeth, called Aristotle's
lantern
 Starfish can push
there stomachs
through their mouths
and insert it into clams
Chordata
 All vertebrates
(animals with
backbones) are
Chordates.
 They take in their food
and the digestive
system works to break
it down, and then it
exits the body.
* includes: fish,
amphibians, reptiles,
birds, mammals.
Circulatory System
 The digestion
process breaks
down food into small
components the
blood absorbs
 The circulatory
system then
transports the food
all around the body.
Excretory System
 After the digestive
system picks out
sugars, proteins and
fats, the body has to
remove things such as
nitrogen, phosphorous
and sulfur.
 Waste then exits the
body through the
excretory system
References
 http://digestive-system.emedtv.com/digestivesystem/function-of-the-digestive-system.html
 http://www.estrellamountain.edu/faculty/farabee/
biobk/BioBookDIGEST.html
 http://encarta.msn.com/encyclopedia_76157519
7/digestive_system.html
 http://www.junglewalk.com/info/Spongeinformation.htm
 http://faculty.clintoncc.suny.edu/faculty/michael.g
regory/files/bio%20102/bio%20102%20lectures/
animal%20diversity/lower%20invertebrates/spon
ges.htm
The End!
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