Functions of a
transport/circulatory
system
Invertebrate circulation
1.
2.
a.
Diffusion
b.
Aided by gastrovascular cavity
c.
Water vascular system
Open circulatory system
Closed circulatory system
d.
e.
Vertebrate circulation
3.
a.
b.
Fishes
Amphibians
Reptiles
d. Birds
e. Mammals
c.
1)
2)
3)
4)
5)
6)
7)
Pathway of blood
Cardiac cycle
Maintenance of heartbeat
Principles governing blood
circulation
Lymphatic system
Blood composition and
function
Cardiovascular disease
 Transports materials






Nutrients from digested food
Respiratory gases: CO2 and O2
Waste materials: toxins and nitrogenous wastes
Antibodies
Hormones
Enzymes
 Immune functions
 Maintains homeostasis
 Blood pH
 Heat transport
Gastrovascular cavity in
simple invertebrates
 Cnidarians (e.g. Hydra)




and flatworms (e.g.
planarians)
No system required
Single opening: exchange
of materials with the
environment
Central cavity for
digestion and
distribution of
substances throughout
the body
Body walls two cell
layers thick  materials
undergo diffusion
Water vascular system in
echinoderms
 multi-purpose:
locomotion, food and
waste transport,
respiration
 movement of muscles
pump water into canals
 closed system of canals
connecting tube feet
 madreporite  ring
canal  radial and
lateral canal  tube feet
 ampullae
Open circulatory system
 Phylum Arthropoda,






Phylum Mollusca (with
one exception)
hemolymph
heart(s)  sinuses 
ostia  heart(s)
diffusion from sinuses to
organs
often serve a support
purpose
disadvantage: loss of
pressure in sinuses
insects: well-developed
respiratory systems, O2
not transported through
the blood
Closed circulatory system
or cardiovascular system
 cephalopods, annelids,
vertebrates
 presence of blood vessels
 advantages
1. rapid flow
2. may direct blood to
specific tissues
3. blood cells and large
molecules remain within
vessels
4. can support higher levels
of metabolic activity
 Heart
 Atrium
 Ventricle
 Blood vessels
 Arteries
 Arterioles
 Capillaries and
capillary beds
 Venules
 Veins
 Blood
FISHES
 Single-circulation
 Fish heart
 2-chambered
 atrium and ventricle
 African lungfish heart
 3-chambered
 2 atria
 LA: O2-rich blood
 RA: O2-poor blood
 spiral fold
 partially divided
ventricle
Amphibians
 Pulmocutaneous and
systemic circulation are
partly separated
 Amphibian heart
 1 ventricle
 2 atria:
 LA: O2-rich blood
 RA: O2-poor blood
 advantage: oxygen-rich
blood reaches the
body’s organs faster
 disadvantage: some
mixing of O2-rich and
poor blood occurs
Reptiles
 Reptilian heart
 3-chambers
(crocodilians have 4)
 2 atria
 1 ventricle (2 in
crocodiles and
alligators)
 partially divided,
decreases mixing
Birds and Mammals
 4 chambered heart:
 2 atria
 2 ventricles
 full separation of
pulmonary and systemic
circuits
 Advantages
1.
2.
3.
no mixing of oxygenated and
deoxygenated blood
gas exchange is maximized
pulmonary and systemic circuits
operate at different pressures

Importance
1.
Endothermic  high nutrient and
O2 demands in tissues
2.
Numerous vessels  great deal of
resistance, so requires high
pressure
 R side of heart:
 pulmonary circuit
 L side of heart:
 systemic circuit
 one way valves:
 atrioventricular
valves
 semilunar valves
1.
right atrium receives O2poor blood from superior
and inferior venae cavae
2.
from right atrium into the
right ventricle through the
tricuspid valve
3.
pumped into the
pulmonary artery through
the pulmonary semilunar
valve to lungs
4.
O2-rich blood from lungs is
returned to the left atrium
via the pulmonary veins
5.
enters the left ventricle via
the mitral or bicuspid valve
6.
exits the left ventricle into
the aorta via the aortic
semilunar valve
7.
circulated to body tissues