Transport
in
Animals
Part 1: Single and Double
Circulatory systems
Levels of Organisation (from
Year 9)
CELLS are the smallest structural and
functional unit of every organism.
Groups of cells with similar structures,
performing a shared function form a
TISSUE.
An ORGAN is a structure made up of a
group of tissues, working together to
perform a specific function.
Several organs with related functions
working together to perform a body
function form an ORGAN SYSTEM.
Groups of organs systems together make
up an ORGANISM.
Why is it called the ‘circulatory
system’?
Organs:
Heart
+ Vessels
(these are
CELLS are
the smallest
structural
and
considered
to of
beevery
tubular-like
organs)
functional
unit
organism.
Related
a pump
that
Groups offunctions
cells with–similar
structures,
pushes
blood
around
the body,
performing
a shared
function
form a
delivering
TISSUE. oxygen to respiring cells,
vessels
provide
a transport
An ORGAN
is a structure
madesystem
up of a
for blood
ensuring
one-way
flow!to
group
of tissues,
working
together
perform a specific function.
Several organs with related functions
working together to perform a body
function form an ORGAN SYSTEM.
Groups of organs systems together make
up an ORGANISM.
These organisms don't need
a circulatory system. Why?
And yet why do we need one?
Amoeba: unicellular
protozoan
Tapeworm: flatworm
1mm thick.
Earthworm: round and
segmented worm.
BO
NU
IN F S
O
Functions of the Circulatory System
To carry O…………….. to all the cells in the body
To carry F…………. to all the cells in the body
To remove W…………… from the cells of the body
To distribute H……………. around the body
To form part of the D……………….. the body has against
microbes (harmful organisms)
To H………………. itself and prevent blood loss by clotting
Study the diagram:
Why do you think this is called a
single circulatory system?
Blood has to pass through two
capillary systems, those of the
gills and the body, before returning
to the Heart. This results in a
marked drop in blood pressure
before the blood completes a
circuit - exchange of materials is
not so good; adequate for fish but
not mammals.
*Single links to heart with 2
chambers
Study the diagram:
Why do you think this is called a
double circulatory system?
Bonus Q1) Describe the pathway
that the blood takes during one
circulation.
Bonus Q2) What are the
advantages of this system?
• A suitable medium in which to carry materials. This is
normally a liquid based on water i.e.…………………………..
• A closed system of tubular vessels that contains the
transport medium i.e.…………………………..
• A mechanism for moving the transport medium within
the vessels i.e.…………………………..
• A mechanism to maintain the flow of the medium in one
direction i.e.…………………………..
• A means of controlling the flow to meet the changing
needs of the organism i.e.…………………………..
By meticulous dissection and
ingenious experiments Harvey
showed that the blood flows away
from the heart in arteries and
returned in veins.
On tying a ligature around the
upper arm, the valves in the veins
show up as small swellings. If
blood is pushed up to a point above
one of these swellings, it fails to
flow back even if pushed,
indicating that the normal direction
of blood flow is towards the base
of the arm.
However, he was unable to
demonstrate the existence of
vessels connecting the arteries
and veins.
Homework
Conduct some research into the historical
discoveries of circulation including contributions
from the following six people: Galen, Harvey, Malphigi,
de Vinci, Vesalius and Fabricius. A mini timeline
would be useful