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4.2 Organisation Lesson 11
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Valves and blood flow
Specification references
 4.2.2.2 The heart and blood vessels
Aims
You will by now be familiar with the structure of the heart and
that it is made up of two pumps, each with chambers separated
by valves. On completion of this activity you will be able to
describe how the valves in the heart open and close due to
blood pressure changes in the chambers and vessels and
explain why this is important to maintain the correct direction of
blood flow.
Learning outcomes
After completing this worksheet, you should be able to:
 describe the role of blood pressure in the chambers of the heart in opening
and closing valves
 explain why this is important.
Questions
Imagine two rooms full of people that are connected by a set of doors which
overlap so that they can only open one way, shown in the diagram below by the
thick diagonal lines. They can only open to the right. If they are pushed to the
left they will shut.
A
B
1 a If the people pushing on the walls and doors of room A pushed harder than
those in room B, what would happen to the doors?
(1 mark)
b Where would the people move if this happened?
(1 mark)
© Oxford University Press 2016
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original.
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4.2 Organisation Lesson 11
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c If the people in room B were pushing harder than those in room A, what
would happen to the doors?
(1 mark)
d Could the people move back into room A if this happened?
(1 mark)
Now imagine there is a third room of people, room C, again connected by doors
that will only open one way.
A
B
C
2 a If the people pushing on the walls and doors of room B pushed harder
than those in room C, what would happen to the doors?
(1 mark)
b Where would the people move if this happened?
(1 mark)
Now imagine that room B is bent around into a corridor with the doors to room C
at the top. Note that the doors are still pointing in towards room C, even though
they look like they are going in the opposite direction due to the bent corridor.
This time room C has no end wall.
3 a Would this work in the same way as the previous diagram?
(1 mark)
© Oxford University Press 2016
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original.
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4.2 Organisation Lesson 11
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b Where would the people eventually have to leave the set of rooms?
(1 mark)
Now suppose we turn the rooms sideways and put a corridor with no doors
labelled D, which leads into room A. We also have a mirror image set of rooms
opposite, with rooms and corridors labelled W, X, Y, and Z. There are sets of
one-way doors in the corridors W and D.
4 a Suppose corridor Z eventually leads to corridor D and corridor C leads to
corridor W. Write down the only order of letters possible to pass through
whilst going through this set-up, starting with A
(1 mark)
b What opens the doors?
(1 mark)
c What closes the doors?
(1 mark)
This represents how the heart works, with chambers and blood vessels instead of
rooms and corridors, and blood instead of people.
d Which type of blood vessels are D and W?
(1 mark)
© Oxford University Press 2016
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original.
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4.2 Organisation Lesson 11
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e Which type of blood vessels are C and Z?
(1 mark)
f What would there be between C and W?
(1 mark)
g What would there be between Z and D?
(1 mark)
Extension
5 Draw a sketch graph with two lines on it to show how the pressure would
change over time in Y and Z during a heartbeat.
(2 marks)
6 Why is it important that blood only flows in one direction? (Think about the
answers to Questions 4f and 4g.)
(2 marks)
7 Name the vessel or chamber shown by each letter.
(8 marks)
© Oxford University Press 2016
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original.
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