LG 3 – Gas Exchange, Circulation, Digestion, and Excretion
Invertebrates
Gas Exchange
Aquatic –
Terrestrial –
Circulation
Open Circulatory System –
Closed Circulatory System –
Digestion
Intracellular –
Extracellular –
Excretion
Aquatic –
Terrestrial –
Vertebrates
Gas Exchange
Aquatic –
Terrestrial –
Circulation
Fish –
Amphibians –
Reptiles –
Crocs, Birds, Mammals –
Digestion
Extracellular –
Carnivores vs Herbivores –
Excretion
Kidneys –
Function -
Unit III
Anatomy and Physiology of
Animals
Learning Goal 3
Describe systems for gas exchange,
circulation, digestion, and excretion in
animals.
Invertebrates
–
–
Gas Exchange
Most aquatic
invertebrates
exchange oxygen
and carbon dioxide
through gills. They
are feathery
structures that
expose a large
surface area to the
water. Examples:
mollusks,
arthropods.
• Terrestrial Invertebrates
• have respiratory
surfaces covered with
water or mucus. They
range from book lungs
in spiders
• to spiracles (openings)
that open into tracheal
tubes in insects.
•
•
Circulation
Open circulatory
system – blood
contained in vessels
and sinuses (large
spaces) pumped by
one or more heart-like
organs. Examples:
arthropods and most
mollusks
• Closed circulatory
system
a heart-like organ
forces blood
through vessels that
extend throughout
the body.
Examples: annelids
and some mollusks
Digestion
Intracellular digestion
Small particles of
food enter cells, and
are broken down,
then nutrients are
passed to other cells.
Examples: sponges,
jellyfish
Extracellular digestion
Food is broken
down outside of
cells in a digestive
cavity or tract then
absorbed by cells.
Examples:
mollusks, annelids,
arthropods
Excretion:
Aquatic
Invertebrates
Ammonia (a toxic
by-product of
protein break
down) moves out
of cells directly
into surrounding
water.
Terrestrial
Invertebrates
Tube-like
structures called
nephridia turn
ammonia into less
toxic substances
like urea and uric
acid, then release
it into the
environment.
Vertebrates
–
–
Gas Exchange
Gills in aquatic
vertebrates like fish
and amphibian
larvae (tadpoles)
– Lungs in terrestrial
vertebrates like mature
amphibians, reptiles,
birds, and mammals.
– Both gills and lungs
consist of moist surfaces
containing many tiny
blood vessels through
which oxygen and
carbon dioxide move.
•
•
Circulation
Fish – single loop
circulatory system
with a two
chambered heart.
• Amphibians –
double loop system
with one loop
carrying blood
between the heart
and lungs and the
other loop carrying
blood between heart
and rest of body.
Heart has three
chambers.
Reptiles
have a double loop
system with a three
chambered heart,
but the heart is
partitioned so that
there is less mixing
of oxygen-poor and
oxygen-rich blood
than in amphibians.
• Birds, mammals,
and crocodilians
have a fourchambered
completely divided
heart in a double
loop system.
Digestion
All vertebrates
have extracellular
digestion with
digestive organs
suited for different
feeding habits.
Carnivores have
short digestive
tracts, while
herbivores have
longer digestive
tracts.
Excretion
Most vertebrates
rely on kidneys to
get rid of
nitrogenous waste.
Function
As proteins are
broken down,
ammonia forms but is
converted to less
toxic urea or uric
acid, then eliminated
by the kidneys.
Functional unit of the
kidney is the nephron.
Kidneys are also
important in
regulating water and
other substances in
body fluids.
LG 3 Terms
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Gills vs Lungs Spiricles –
Tracheal Tubes –
Open Circulatory System –
Closed Circulatory System –
Intracellular Digestion –
Extracellular Digestion –
Nephridia –
Kidneys –
Nephron –