2C1 Circulatory Systems
2C1 Circulatory Systems
2C1 Circulatory Systems
Starter:
What is a circulatory system?
What does it do?
Learning objectives:
• Understand why simple, unicellular organisms
can rely on diffusion for movement of
substances in and out of the cell
What do larger animals have to make sure they get all the
oxygen they need?
Can you make the connection?
What do larger animals have to make sure they get all the
oxygen they need?
They have gas exchange organs and circulatory systems.
For example – lungs in mammals and gills of fish
Circulatory System
Function:
To transport materials to the cells
in the body e.g. oxygen, glucose
and to remove waste materials
(products of excretion) from cells
e.g. carbon dioxide, urea
Components:
• pump – heart
• tubes – humans have a closed
circulatory system, where the
blood is transported in blood
vessels
• liquid – blood
A double circulatory system
During one complete
circuit of the body,
blood passes through
lungs
the heart twice.
The deoxygenated
blood needs to lose
the carbon dioxide and body’s
pick up more oxygen.
How does it do this? cells
How does blood circulate around the body?
Next, the right side
of the heart pumps lungs
deoxygenated blood
to the lungs.
In the lungs the blood
gets rid of the waste
carbon dioxide and
collects more oxygen.
Where does this
oxygenated blood
then travel to?
body’s
cells
How does blood circulate around the body?
The oxygenated
blood then returns
to the left side of the lungs
heart. pulmonary
This completes the circulation
blood’s journey
around the body.
Why is the journey
of blood through the systemic
circulatory system
called a double
circulation
circulation? body’s
For every circuit of the body, cells
blood passes through the
heart twice
Two sides of the heart:
Oxygenated blood
Right side contains
Deoxygenated blood body’s
cells
Two sides of the heart separated by a wall = septum
Circulatory system
Assess your learning:
Look at the diagram of the
circulatory system in fish.
How many differences can you see
between the circulation in a fish and
in a human?
What type of circulation is this?
Why is it called this?
Extension:
Describe the circulatory system of
an insect?
Why do different animals have such
different circulatory systems?
Comparison of the single and double circulation systems
Advantages of the Double Circulatory System
Double circulatory system allows:-
A) blood to be pumped at low pressure to
the lungs
B) blood to be pumped at high pressure to
the body
C) oxygenated and deoxygenated blood to
be kept separate
Advantages of this?
D) Low pressure – doesn’t damage lungs
E) High pressure – ensures blood (carrying
oxygen and nutrients) reaches organs
quickly
F) Efficient delivery of oxygen to tissues
and removal of carbon dioxide
lungs
Can you
i) label the main blood
vessels:
• aorta
• vena cava
• pulmonary artery heart
• pulmonary vein
• renal artery
• renal vein?
ii) show the direction of kidneys
blood flow?
body
Q: how do we make sure the blood only
travels one way round the body?