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# ___ Circulation (Ch 27.3)
Type of Circulatory System
Drawings
Found in which animals?
Describe the heart (or
heart-like) organ
Describe relative efficiency.
Why is this so?
Open
Draw what it would look like in a
grasshopper
Arthropods
mollusk
One or more hearts
- 1 chamber
hemolymph (blood
+ other body fluids)
Least efficient
- low pressure
- mixing of O2 &
CO2 rich blood
Draw and color-code a single-loop closed
circulatory system
aquatic vertebrates
with gills
- fish
Two chambers
- 1 ventricle
- 1 atrium
Somewhat efficient
- some pressure
(1 pump)
- separated O2
and CO2 rich
blood
- low O2 content
Draw and color-code a double-loop
closed circulatory system
terrestrial vertebrates 3 or 4 chambers
with lungs
- 2 ventricles
- mammals
- 2 atria
- reptiles
Lungs  heart 
- amphibians
body  heart
Double loop – goes
to the heart twice in
one cycle
(Sketch the inset picture of Figure
27-9 below)
Closed
(Sketch the inset picture of Figure
27-10 below)
Most efficient
- High pressure
(2 pumps)
- separated O2
and CO2 rich
blood
- high O2 content
Compare and contrast open and closed circulatory systems
Infer how many chambers a bird’s heart has. Justify your answer.