Circulatory system
, Introduction and Evolution
organisms such
sponges cnidarians ljellyfish)
•
as , ,
ctenophores ( comb jellies) ,
flatworms, or nematodes ( roundworms )
have specialized
no
circulatory structures
smaller diffusion distribute
•
organisms use simple to
materials to their cells , and because the
they are smaller
,
materials have a much shorter distance to travel
allowing for
simple diffusion to work just fine .
Larger organisms
•
need specialized structures to
transport nutrients to
their tissues because diffusion would
simple not efficiently
transport over such
large distances .
Reminder Diffusion
-
: is the movement of molecules from an area
of
higher concentration of that molecule , to an area of lower
concentration LUSS of that molecule present)
there
systems :
•
of
are two
types circulatory
Open Closed
the heart has distinct circulatory
•
blood
•
pumps fluid
vessels with blood vessels that
into open enclosed in
transport
ends it to and
interstitial fluid ! this is the
simply fluid from the heart
surrounding cells , found in the spaces around them
°
the blood comes materials still
out the
necessary
◦
open ends mixes interstitial fluid
and get to the
fluid
with the interstitial .
through capillaries lthe smallest
This mixture is called blood vessel ) where the
hemolymph walls are thin
enough
this fills to
permit diffusion
large spaces into
•
called sinuses which make the interstitial fluid
up the hemocoel [ blood cavity )
not part of the coelem ]
◦ as the site of gas exchange began to involve
lungs and metabolic rates increased ,
the vertebrate
cardiovascular system developed
, Introduction and Evolution
organisms such
sponges cnidarians ljellyfish)
•
as , ,
ctenophores ( comb jellies) ,
flatworms, or nematodes ( roundworms )
have specialized
no
circulatory structures
smaller diffusion distribute
•
organisms use simple to
materials to their cells , and because the
they are smaller
,
materials have a much shorter distance to travel
allowing for
simple diffusion to work just fine .
Larger organisms
•
need specialized structures to
transport nutrients to
their tissues because diffusion would
simple not efficiently
transport over such
large distances .
Reminder Diffusion
-
: is the movement of molecules from an area
of
higher concentration of that molecule , to an area of lower
concentration LUSS of that molecule present)
there
systems :
•
of
are two
types circulatory
Open Closed
the heart has distinct circulatory
•
blood
•
pumps fluid
vessels with blood vessels that
into open enclosed in
transport
ends it to and
interstitial fluid ! this is the
simply fluid from the heart
surrounding cells , found in the spaces around them
°
the blood comes materials still
out the
necessary
◦
open ends mixes interstitial fluid
and get to the
fluid
with the interstitial .
through capillaries lthe smallest
This mixture is called blood vessel ) where the
hemolymph walls are thin
enough
this fills to
permit diffusion
large spaces into
•
called sinuses which make the interstitial fluid
up the hemocoel [ blood cavity )
not part of the coelem ]
◦ as the site of gas exchange began to involve
lungs and metabolic rates increased ,
the vertebrate
cardiovascular system developed
