The Heart and Circulatory System of 49 © Boardworks Ltd 2004 KS4 Biology The Heart and Circulatory...
-
Upload
vuongkhuong -
Category
Documents
-
view
254 -
download
8
Transcript of The Heart and Circulatory System of 49 © Boardworks Ltd 2004 KS4 Biology The Heart and Circulatory...
© Boardworks Ltd 20041 of 49
KS4 Biology
The Heart and Circulatory System
© Boardworks Ltd 20042 of 49
How the heart pumps blood
The Heart and Circulatory System
The circulatory system
Structure of the heart
Valves in the heart
Summary quiz
Contents
© Boardworks Ltd 20043 of 49
Which organs are involved in
this system?
How do substances move around the body?
The body has its own transport
system that carries substances
around the body.
The body’s transport system is
called the circulatory system.
Why is it given this name?
heart
blood vessels
blood
© Boardworks Ltd 20044 of 49
What is carried by the circulatory system?
carbondioxide
oxygen
Which gases are transported to and from the body’s cells
by the blood flowing in the circulatory system?
Oxygen is the gas needed for respiration and is transported
to the body’s cells.
Carbon dioxide is the waste gas produced by respiration
that must be carried away from the body’s cells.
© Boardworks Ltd 20045 of 49
The arrangement of the circulatory system means that these
two types of blood do not mix. Why is this important?
Two types of blood
The circulatory system carries two types of blood:
oxygen-rich
blood
c
oxygen-poor
blood
blood traveling
to the body cells
high oxygen content
low carbon dioxide
content
blood traveling
away from the body cells
low oxygen content
high carbon dioxide
content
© Boardworks Ltd 20046 of 49
How are the two types of blood (oxygen-rich and
oxygen-poor) kept apart inside the heart?
At the heart of the circulatory system
The heart is the organ at the centre of the circulatory system.
It pumps blood around the body.
© Boardworks Ltd 20047 of 49
Inside the heart
The inside of the heart is divided into two sections so that
the two types of blood (oxygen-rich and oxygen-poor)
are kept apart.
oxygen-poor
blood
right side
of the heart
oxygen-rich
blood
left side
of the heart
Remember that the heart is always labelled as if it is in a
body facing you, so the right side of the heart is on the
left of the diagram.
© Boardworks Ltd 20048 of 49
The two sides of the heart
© Boardworks Ltd 20049 of 49
How does blood circulate around the body?
Blood is pumped
around the body by
the heart.
It takes about 30
seconds for blood to
go once around the
body.
Starting with the left
side of the heart,
what route does the
blood follow to
complete one circuit
of the body?
© Boardworks Ltd 200410 of 49
How does blood circulate around the body?
The left side of
the heart pumps
oxygen-rich blood
to the rest of the body.
This blood supplies
the body’s cells with
oxygen.
What gas does the
blood then pick up
from the body’s cells
and where does the
blood go next? body’s
cells
body’s
cells
© Boardworks Ltd 200411 of 49
The oxygen-poor
blood needs to lose
the carbon dioxide and
pick up more oxygen.
How does it do this?
How does blood circulate around the body?
Blood picks up
carbon dioxide from
the body’s cells.
This oxygen-poor
blood then travels
back to the right side
of the heart.
body’s
cells
body’s
cells
© Boardworks Ltd 200412 of 49
lungslungs
Where does this
oxygen-rich blood
then travel to?
How does blood circulate around the body?
Next, the right side
of the heart pumps
oxygen-poor blood
to the lungs.
In the lungs the blood
gets rid of the waste
carbon dioxide and
collects more oxygen.
body’s
cells
body’s
cells
© Boardworks Ltd 200413 of 49
The oxygen-rich
blood then returns
to the left side of the
heart.
This completes the
blood’s journey
around the body.
Why is the journey
of blood through the
circulatory system
called a double
circulation?
How does blood circulate around the body?
body’s
cells
body’s
cells
lungslungs
© Boardworks Ltd 200414 of 49
During one complete
circuit of the body,
blood passes through
the heart twice.
The heart has two
jobs to do and so the
circulatory system
involves a double
circulation.
What are the two jobs
that the heart carries
out during this double
circulation?
A double circulatory system
body’s
cells
body’s
cells
lungslungs
© Boardworks Ltd 200415 of 49
Which way does blood flow?
© Boardworks Ltd 200416 of 49
The Heart and Circulatory System
The circulatory system
Structure of the heart
How the heart pumps blood
Valves in the heart
Summary quiz
Contents
© Boardworks Ltd 200417 of 49
The structure of the heart – exterior
The heart pumps blood around the circulatory system.
What is the heart made of?
The heart is made of muscle and keeps pumping blood
around your body, even when you are asleep!
muscle
tissue
What do the blood vessels on the outside of the heart do?
© Boardworks Ltd 200418 of 49
The heart needs blood too!
The heart is full of blood but also needs its own blood
supply so that the muscle can keep pumping.
blood vessels
supply blood
to muscle tissue
The blood vessels on the outside of the heart carry
oxygen-rich blood to the heart muscle cells.
Oxygen-poor blood is then carried away from these
cells by outer blood vessels and back into the heart.
muscle
tissue
© Boardworks Ltd 200419 of 49
The structure of the heart – interior
The inside of the heart is divided into two sections to keep
oxygen-rich and oxygen-poor blood separate.
Each side of the heart is also divided into two sections.
Each section of the heart is called a chamber.
How many chambers are there?
right side
of the heart
left side
of the heart
4
© Boardworks Ltd 200420 of 49
The chambers of the heart
The four chambers of the heart have special names:
A lower chamber is called a ventricle.
An upper chamber is called an atrium (plural atria).
rightventricle
rightatrium
leftventricle
leftatrium
© Boardworks Ltd 200421 of 49
What do atria and ventricles do?
The chambers of the heart have different functions.
The atria collect blood that enters the heart.
The ventricles pump blood out of the heart.
blood tothe body
blood from the body
blood to the lungs
blood from the lungs
© Boardworks Ltd 200422 of 49
Inside the heart – labels
© Boardworks Ltd 200423 of 49
Inside the heart – labelling activity
© Boardworks Ltd 200424 of 49
Chambers of the heart – activity
© Boardworks Ltd 200425 of 49
The Heart and Circulatory System
The circulatory system
Structure of the heart
How the heart pumps blood
Valves in the heart
Summary quiz
Contents
© Boardworks Ltd 200426 of 49
Preventing backflow
Blood always flows in the same direction as it moves
through the heart during each circulation of the body.
Why is it important that blood does not flow backwards?
© Boardworks Ltd 200427 of 49
The chambers of the heart are separated by valves
which prevent blood from flowing in the wrong direction.
Heart valves
There are valves between the atria and the ventricles…
…and there are valves leading out of the ventricles.
valve between
right atrium and
right ventricle
valve between
left atrium and
left ventricle
valve leading
out of
right ventricle
valve leading
out of
left ventricle
© Boardworks Ltd 200428 of 49
Naming the heart valves
© Boardworks Ltd 200429 of 49
How are valves held in place?
The valves between the atria and ventricles are connected
to the inner walls of the heart by tough tendons.
valve open
© Boardworks Ltd 200430 of 49
How are valves held in place?
The tendons allow the valves to close and hold the valve
flaps in place. They prevent the valves from flipping up
and turning inside out. Why is this important?
valve open valve closed
© Boardworks Ltd 200431 of 49
How do valves work?
A valve acts like a door that only opens in one direction.
If the door is held by someone at a fixed point, only the arm
moves as the door opens and closes.
When the door is closed the arm is fully extended, so the
door can only be opened in one direction.
© Boardworks Ltd 200432 of 49
How do valves work?
A valve acts like a door that only opens in one direction.
In the heart, the tendons holding the valve are like the
arm holding the door.
One end of each tendon is fixed to the wall of the heart
and so the valve can only open in one direction.
© Boardworks Ltd 200433 of 49
The Heart and Circulatory System
The circulatory system
Structure of the heart
How the heart pumps blood
Valves in the heart
Summary quiz
Contents
© Boardworks Ltd 200434 of 49
How does the heart pump blood?
Imagine the force needed
to squeeze a tennis ball.
That’s how much force
the heart uses to pump
blood around the body!
How does the heart produce
enough force to keep doing
this 24 hours a day?
The heart can pump blood
because it is made of muscle.
Muscle tissue works by
contracting (squeezing)
and relaxing.
© Boardworks Ltd 200435 of 49
How does the heart pump blood?
All the parts of the heart on
either side, work together
in a repeated sequence.
The two atria contract and
relax; then the two ventricles
contract and relax.
This is how blood moves
through the heart and is
pumped to the lungs and
the body.
One complete sequence of
contraction and relaxation is
called a heartbeat.
© Boardworks Ltd 200436 of 49
Heartbeat animation
© Boardworks Ltd 200437 of 49
Stages of a heartbeat
Stage 1:
A heartbeat begins
with the heart muscle
relaxed and valves
closed.
Blood flows into the
two atria and both
sides fill up with blood.
This blood has to be
pushed through the
valves to get into the
ventricles. How does
this happen?
© Boardworks Ltd 200438 of 49
Stages of a heartbeat
Stage 2:
The atria contract and
the blood is squeezed
which causes the
valves leading to the
ventricles to open.
Blood then flows from
the atria into the
ventricles.
What happens to the
open valves when the
atria are empty?
© Boardworks Ltd 200439 of 49
Stages of a heartbeat
Stage 2 (continued):
The valves between
the atria and the
ventricles close.
This prevents any
backflow.
What happens next
to the blood in the
ventricles?
© Boardworks Ltd 200440 of 49
Stages of a heartbeat
Stage 3:
Almost immediately,
the ventricles contract
and the blood is
squeezed again.
The pressure of the
blood forces open the
valves leading out of
the heart.
Blood is pumped out
of the heart.
What happens to the
open valves when the
ventricles are empty?
© Boardworks Ltd 200441 of 49
Stages of a heartbeat
Stage 3 (continued):
When the ventricles
are empty, the valves
leading out of the
heart close and the
heart muscle relaxes.
This completes the
sequence of
contraction and
relaxation in one
heartbeat.
What will happen
next?
© Boardworks Ltd 200442 of 49
Stages of a heartbeat
Stage 1 (again):
The atria fill up with
blood as the heartbeat
sequence begins
again.
Why are the walls
of the atria thinner
than the walls of
the ventricles?
Why is the wall of the
left ventricle thicker
than the right
ventricle?
© Boardworks Ltd 200443 of 49
What does a doctor hear when they listen to a patients’ heart?
Listening to a beating heart: lub-dub
The “lub” is caused by
the closing of the valves
leading to the ventricles.
The “dub” is caused by
the closing of the valves
leading out of the heart.
lub-dub,
The sound of a heartbeat is the sound of the heart valves.
lub-dub, lub-dub, lub-dub, lub-dub, lub-dub…
© Boardworks Ltd 200444 of 49
Measuring a beating heart
You can measure how
fast your heart is beating
by taking your pulse.
Each pulse that you feel
is due to the pressure of
blood leaving the heart as
the left ventricle contracts.
Place the fingertips of one
hand on the opposite wrist,
where an artery passes
near the surface of the skin.
What is your heart rate,
in beats per minute,
right now?
© Boardworks Ltd 200445 of 49
…in one hour?
…in one day?
…in one year?
…in 70 years?
How many heartbeats?
If your heart beats at an average rate of 70 times
per minute, how many heartbeats are there…
70 x 60 =
4,200 x 24 =
100,800 x 365 =
36, 792, 000 x 70 =
100, 800
36, 792, 000
2, 575, 440, 000
4, 200
© Boardworks Ltd 200446 of 49
The sequence of a heartbeat
© Boardworks Ltd 200447 of 49
Journey of blood around the body
© Boardworks Ltd 200448 of 49
The Heart and Circulatory System
The circulatory system
Structure of the heart
How the heart pumps blood
Valves in the heart
Summary quiz
Contents
© Boardworks Ltd 200449 of 49
Multiple-choice quiz