Transcript Open and closed circulatory systems

Open and closed circulatory
systems
Year 11: Biology
http://intranet.cbhslewisham.nsw.edu.au:82/science/concepta.asp?conID=13&resource=1
Retrieved 4 June 2011
• Outcome: compare the open
and closed circulatory systems
using one vertebrate and one
invertebrate
The circulatory systems of
invertebrates
• Invertebrates such as insects
have a heart
• The heart of a young snail,
which has a thin shell, can
sometimes be seen by
holding the snail up to the
light and looking up from
below
Insects circulatory
• Invertebrates have an open
circulatory system
• Vertebrates have a closed
circulatory system
• The blood in a closed
circulatory system
remains within the tubes
and materials diffuse in
and out of the blood
through the walls of tiny
tubes called capillaries.
• The circulatory systems in
invertebrates is an open
system
• Invertebrates blood is pumped
at low pressure directly into the
main body cavity where it
slowly flows about the cells
• The blood is collected by open
vessels like drains, which carry
the blood back to the heart like
drains
• This inefficient circulatory
system limits the size of
invertebrates
• Large vertebrates require a
more efficient system to
overcome their low surface
area to volume ratio
• In insects, the open
circulatory system is
supplemented with another
separate open system of gas
exchange
• Insects have a series of
small holes (spiracles),
which open into a
network of tubes called
tracheae.
• These tracheae distribute
oxygen to body cells and
carry away oxygen
• This network relies
on diffusion to move
gases through them
• Unlike vertebrates,
which transport
wastes, nutrients
and gases in insects
occurs through two
systems
• In vertebrates,
nutrients, oxygen, CO2
and other wastes are
transported by the
circulatory system.
Questions
• 1. Name three animals that
would have a closed
circulatory system
• 2. Name three animals that
would have an open
circulatory system
• 3. Vertebrates can grow
much larger than insects,
explain why this is so in
terms of their circulatory
capacity