Transcript Comparative Digestive Systems

Comparative Digestive Systems
Biology 11
G.Burgess
2006
Digestion
• The breakdown of nutrient
materials into smaller
absorbable particles.
• There are two main forms of
digestion
– Mechanical Digestion: breaking
down of materials physically (ie.
Chewing food)
– Chemical Digestion: breaking
down of materials by adding acids,
bases and enzymes (ie. Salivary
amylase breaks down starch into
maltose in your mouth)
Unicellular organisms
• Most unicellular organisms do
not require digestion because
most of their nutrients are
already small enough to be
absorbed into the cell
• However, some, like the
paramecium are able to bring in
solid particles as food vacuoles.
These use lysosomes (packed
with hydrolytic enzymes) to
breakdown the contents of the
food vacuoles.
Plants
• Plants and other autotrophic
organisms do not always
require digestion.
• As always, there are exceptions
• Plants that cannot get nitrogen
from the soil (ie. Venus fly trap
or pitcher plant), get nitrogen
by digesting insects in
specialized leaf structures that
secrete digestive enzymes.
Multicellular organisms
• Multicellular organisms have a variety of
specialized digestive organs.
• Annelids (ie. earthworm) have a series of
organs for digesting
• Mouth, pharynx, esophagus, crop, gizzard, intestine
• Orthopterans (grasshoppers) use the same
type of digestive parts as the earthworm,
however, they also have an organ called the
gastric caeca.
• Amphibians (frog) also have much the same
type of digestive organs, however, they do
not have a crop or gizzard. Instead, they
have a stomach.
• Each of these organisms also have
specialized mouth parts so that they can eat
their natural foods.
Earthworm Digestive System
•Pharynx
•Mouth
•Esophagus
•Crop
•Gizzard
•Intestine
•Anus
Grasshopper Digestive System
Mouth
Crop
Esophagus
Gizzard
Intestine
Anus
Frog Digestive System
•Esophagus
•Stomach
•Liver
•Galbladder
•Intestine
•Cloaca
•Anus
Human Digestive System
•Mouth
•Pharynx
•Esophagus
•Liver
•Gallbladder
•Stomach
•Small intestine
•Large intestine
•Rectum
•Anus