Transcript heart and circulatory system

KEY STAGE 4
THE HEART AND
CIRCULATORY SYSTEM
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How are substances transported around the body?
The next organ system we will be considering can be
known by two names…..
Blood system
Circulatory system
The circulatory system is made of two parts:
1. The heart
2. The blood vessels
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One of the substances that the circulatory system
transports are respiratory gases.
For example, the Oxygen that the body needs, must
be taken to the cells and the Carbon Dioxide waste
gas must be taken away from the cells.
As these gases are carried by the blood, it means that in
terms of the presence of gas, we have two types of blood.
Blood high in oxygen
Blood low in oxygen
Oxygenated
Deoxygenated
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At all times these two types of blood cannot mix. Why do
you think this is?
Because of this our circulatory system is in two parts. It is in
fact called a double circulatory system.
Lungs
This section of the
system including
the right side of
the heart, deals
with the
deoxygenated
blood.
This section of the
system including
the left side of the
heart, deals with
the oxygenated
blood.
Body cells
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The Human Circulatory System
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In this unit we are going to focus on the heart..
The Heart
This is the pump at the centre of the circulatory system.
Not all living organisms have hearts.
Also, the shape of the heart can change, depending on
what species you look at.
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The heart is made almost entirely of muscle. It is unlike
any other muscle in your body because it never tires.
And even though it is full of blood it still needs it own
blood supply. Oxygenated blood is carried to the heart
by the coronary arteries.
Each side of the heart has two chambers.
1. An top chamber or atrium and
2. A bottom chamber or ventricle
Each of these chambers has its own function. Look at the
diagram on the next slide to see what that is.
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The Heart
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Besides the chambers there is also another very
important part of the heart – the valves. These valves
are found between the top and bottom chambers on
both sides of the heart.
These valves are
rather like doors
that only open in
one direction.
blood
valve
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As the atrium fills
with blood, the
valves are
closed.
When the atrium
contracts and
squeeze the blood,
the valves are
pushed open
These valves are connected to the side wall of the heart
by tough tendons. These tendons allow the valves to
close but not invert.
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valve
tendon
These tendons
can be compared
to an arm holding
onto the handle of
a door.
wall of
ventricle
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The arm
bends
as the
door is
opened.
When the
door is
closed the
arm is fully
extended.
It would be impossible for the door to open in the
other direction without the person moving with it.
The tendon (represented by the arm) is held in a fixed
position and therefore the valve (door) can only open
in one direction.
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The blood will
naturally
push against
the valve.
However, the
valves remain
firmly shut.
In this way, the blood can be moved from chamber to
chamber quite efficiently. The valves prevent the blood
from moving in the wrong direction.
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We also
find valves
here
...and here!
These extra valves stop the blood from re-entering the
heart when it is pumped from the ventricles.
When the blood knocks against the first heart valves, it
makes a ‘lub’ like sound.
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When the blood knocks against the second set of
heart valves, it makes a ‘dub’ like sound.
Artery
Ventricle
The blood ‘slaps’ against
the valve and then
passes along the artery.
Valve
These two sounds – lub and dub – are actually what we
hear as our heartbeat. So our heartbeat is in fact the sound
of the valves opening and closing.
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The following diagram shows the position and
name of the main valves in the heart.
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Now that we can name all of the parts of the heart it is
time to see how they work to push blood around the body.
The heart pumps blood when its muscle contracts. As
the muscle contracts the chamber gets smaller and
squeeze the blood out.
The two sides of the heart work together. The atria
contract and relax at the same time, as do the ventricles.
The next two slides describe what occurs inside the heart
during one heart cycle.
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Blood from
the body
Blood from
the lungs
1. The heart beat begins
when the heart muscles
relax and blood flows into
the atria.
2. The atria then contract and
the valves open to allow
blood into the ventricles.
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3. The Ventricles contract
forcing the blood to leave the
heart. At the same time, the
atria are relaxing and once
again filling with blood.
The staged cycle then repeats itself.
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Just before we finish our study, let’s take a last
look at the heart…..
Do you notice anything
different about the two
sides of the heart?
Well, the left ventricle wall is
clearly thicker than the right
ventricle wall.
Why is this?
To answer this question, think about where the blood is
going when it leaves the right and left ventricles.
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Lungs
This journey is
far less
demanding. The
right ventricle
only has to pump
blood from the
heart to the
adjacent lungs.
This journey is
enormous. The
left ventricle has
to pump blood all
over the body!
Body cells
Therefore, the left ventricle needs a thicker wall to
generate a stronger ‘squeeze’ on the blood.
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Drag the labels to the correct numbered boxes
on the diagram of the blood system
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Multiple choice questions
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What is the alternative name for the blood
system?
A the heart system
B the circulatory system
C the transporting system
D the pumping system
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Which of the following organs are found in the
blood system?
A heart, lungs, brain and bladder
B arteries, heart and stomach
C arteries, veins and heart
D heart, veins and pancreas
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The function of the circulatory system is to...
A transport substances, such as oxygen and dissolved
nutrients, around the body.
B support the movement of the body.
C digest large molecules of food.
D carry chemical messages between the brain and the
nerves.
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What is the wall of the heart mainly made
from?
A. fat tissue
B. skin tissue
C. nerve tissue
D. muscle tissue
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The blood system is often known as the “double
circulation” system. Why is this?
A The blood carries two vital materials.
B There are actually two parts to the heart.
C The system is divided into two separate circuits.
D The blood flows in two directions.
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How many chambers are there in the human
heart?
A four
B it varies from human to human
C two
D none of the above
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Look at the diagram below.
W
X
Y
Z
Name the chamber that is labelled W (be
careful!).
A the right ventricle
B the left ventricle
C the right atrium
D the left ventricle
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If blood entered the chamber X, where would
it then go?
A It would leave the heart.
B It would pass into chamber Z.
W
X
Y
Z
C It would pass across into chamber W.
D It would flow into all the other chambers.
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Which chamber is the left ventricle?
A W
W
X
Y
Z
B X
C Y
D Z
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Which side of the heart has the thickest wall?
A the left
B the right
W
X
Y
Z
C both sides are the same thickness
D middle is thicker
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Into which chambers does blood enter the
heart?
A the right and left atrium
B the right and left ventricle
C the right atrium and the left ventricle
D the right ventricle and the left atrium
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Through which two chambers does blood
leave the heart?
A the right and left atrium
B the right and left ventricle
C the right atrium and the left ventricle
D the right ventricle and the left atrium
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Which of these combinations lists the two
circuits that blood makes through the body?
A Heart - Lungs - Body - Lungs
B Heart - Body - Heart - Body - Lungs
C Body - Lungs - Heart - Body - Heart
D Heart - Lungs - Heart - Body
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Look at the diagram
below.
P
S
Q
R
T
U
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What is part T?
A an atrium
P
S
B a ventricle
Q
R
C a capillary
T
D a chamber
U
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Part Q shows...
A a heart valve.
P
S
B the atrium.
Q
C a chamber.
D a heart door.
R
T
U
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Arrow R pumps blood to the...
A the ventricles.
P
S
B the body.
Q
C the liver.
D the lungs.
R
T
U
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Arrow P shows the blood coming from the...
A the stomach.
P
S
B the head.
Q
R
C the body.
T
D the lungs.
U
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