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Circulation
Year 8 Science
Blood
• The average human carries about 5 litres
of blood in their body, which travels
around what is known as the Circulatory
System.
• Blood is an integral component in the
function of our bodies. It is made up of the
following:
Blood
Blood types
There are four basic types:
Type A
Type B
Type AB
Type O
This is based on whether you have certain proteins on your blood cells
Each of these has a positive and negative (Rh + and Rh -)
Compatibility
Not all bloods can mix. Some blood
mixtures will clot when added together
- type A:
can only receive types A and O blood.
- type B: can only receive types B and O blood.
- type AB: can receive types A, B, AB, and O blood.
- type O: can only receive type O blood.
Red blood cells carry oxygen
Cells are red
& white blood
cells
Cell fragments are
platelets
Platelets function in
clotting
White blood cells defend against
disease
Red Blood Cells carry oxygen
Haemoglobin is the iron-
Haemoglobin
containing protein attached to
the red blood cells that
transports oxygen from the
lungs to the rest of the body.
Haemoglobin bonds with
oxygen in the lungs, exchanges
it for carbon dioxide
When haemoglobin is carrying
oxygen is it called
oxyhaemoglobin.
Oxyhaemoglobin
The Circulatory System
There are 3 types of blood vessels
Arteries
Veins
Capillaries
Arteries
• These carry blood AWAY from the heart
(Think Arteries Away = AA)
• They are buried deep in the body
• They carry oxygen rich blood (except
for the pulmonary artery!)
Veins
• These carry blood IN to the heart
• (Think veINs=IN)
• They have thinner walls, and valves
that prevent blood flowing backwards.
• They carry oxygen poor blood (except
for the pulmonary vein!)
Vessel Thickness Comparison
Notice the arteries
are thicker as they
need to stand up
to the pressure of
blood that is
coming from the
heart
Veins have valves to
prevent deoxygenated
blood from flowing
backwards
Capillaries
• These carry blood to the cells. They are
between arteries and veins
• They are narrow vessels running throughout
the body (one cell thick in some places)
• They carry oxygen rich blood from the
arteries, past the cells. The oxygen poor
blood is then carried to the veins.
The Circulatory System
Arteries
Veins
Capillaries
Which of these blood vessels:
1.
Takes blood away from the heart?
2.
Carries oxygenated blood?
3.
Contains blood under high pressure?
4.
Is only 1 cell thick?
5.
Contains valves?
Diagram of the Heart
aorta
Study this diagram and answer these
questions in your notebook
1. What side of the heart contains
oxygenated blood? Why?
2. What side of the heart contains
deoxygenated blood? Why?
3. The aorta is the thickest blood vessel
in the body. Can you explain why?
4. The heart has two upper chambers
called the left and right atrium. Which
letters show these? What do you
notice about the blood flow in these
two chambers?
5. The heart has two lower chambers
called the left and right ventricle.
Which letters show these?
6. Vessels ‘a’ and ‘b’ are called
pulmonary vessels. Which are veins
and which are arteries?
Superior
Vena cava
Inferior
Vena cava
Rob the Red Blood Cells Journey!
Rob is a new red blood cell and needs
direction about where he’s going and what
will happen to him on his journey around
the body.
?
Can you help advise him?
Review Questions
•
•
•
•
Where did Rob pick up Oxygen?
Where did Rob take it to?
Why did Rob change colour?
What things would be floating around Rob
in the blood?
• What other cells are there in the blood with
P____ A____
V___ C___
R____ A____
R____ V______
A______
P_______ V___
L___ A____
L___ V______
Pulmonary Artery
Vena Cava
Right Atrium
Right Ventricle
Aorta
Pulmonary Vein
Left Atrium
Left Ventricle