Download Circulatory systems in animals

CIRCULATORY SYSTEMS IN ANIMALS
Biology ATAR Unit2
Chapter 11
Pages 266-274
Heinemann Chapter 9, pages 150-152 (handout)
Keywords
Gastrovascular cavity
Open circulatory system
 Tubular heart
 Ostia
 Open-ended vessels
 Interstitial fluid
Closed circulatory system
 Heart
 Arteries
 Arterioles
 Capillaries
 Venules
 Veins
 Blood
Making connections
Multicellular
organisms need a
circulatory system to
deliver nutrients and
O2 and remove waste
products and CO2
 Organisms have
different types of
systems because of
their size, their
environment and their
activity or metabolic
rate

CIRCULATORY
SYSTEMS
Types of structures
1.
Gastrovascular cavity
2.
Open system
3.
Closed system
Function
 The circulatory system moves O2 from the respiratory
surface to the body tissues and removes CO2 from the body
tissue to the respiratory surface.
 It also transports nutrients, hormones and waste around the
body where necessary.
GASTROVASCULAR
CNIDARIANS
CAVITY:
The gastrovascular
cavity is responsible for
both the digestion of
food and the transport of
nutrients throughout the
body.
 The cavity has only one
opening to the
environment. Food goes
in and waste comes out
that same opening.

OPEN CIRCULATORY SYSTEM:
INSECTS




An open circulatory system
consists of a dorsal tubular
heart(s) that, when it contracts,
forces the fluid out of openended blood vessels
This fluid flows through the
spaces in the body and bathes
the tissues and organs before
returning through holes (ostia)
to the heart.
The fluid moves at low pressures
and slow circulation speeds
The fluid is not like blood, but
like interstitial fluid
Example: insects, snails
OPEN CIRCULATORY
INSECTS
SYSTEM:
These body fluids contain
nutrients which are
obtained from the
digestive system
 They also contain
metabolic wastes, which
are disposed of by the
excretory system.
 The insect has a separate
respiratory system to
exchange gases (O2 and
CO2).
 In most insects, O2 is
delivered directly to the
muscles through the
tracheal system.

CLOSED CIRCULATORY SYSTEMS:
LARGE AQUATIC & TERRESTRIAL ORGANISMS
A closed circulatory system carries
fluid within a network of arteries,
capillaries and veins
 The fluid (blood) has the capacity
to deliver nutrients and O2 to cells
and remove waste products and
CO2 from cells
 Blood does not leave the capillaries
and does not come into direct
contact with other body tissues
 Blood is oxygenated as it flows
through the lungs
 Blood is moved through the
system by a muscular heart
 The heart has 3 or 4 chambers
separated by valves
Example: reptiles, mammals, fish

CLOSED CIRCULATORY SYSTEMS
SUMMARY:
OPEN & CLOSED
CIRCULATORY SYSTEMS
OPEN
CLOSED
Transport fluid No specialised transport
fluid (interstitial fluid)
Blood
Heart
Simple one or two
chambered heart
Three or four chambers
with valves
Vessels
Open-ended, of different
lengths
Arteries, arterioles,
capillaries, venules, veins
Pressure
Very low pressures
Arteries – high pressure
Veins – low pressure
Time taken to
circulate
Long circuit time
Short circuit time
Examples
Snails, arthropods
Birds, fish, mammals