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B5:
Transportation
Transport in Humans
Describe the circulatory
system
 The
blood, heart and blood
vessels make up the
circulatory system.



The heart is a muscular pump
Blood is pumped around the
body in one direction
There are valves in the heart
and in veins to help control the
direction that blood flows
Double circulation

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.
right side
of the heart
left side
of the heart
oxygen-poor
blood
oxygen-rich
blood
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.
The two sides of the heart
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?
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
Blood picks up
carbon dioxide from
the body’s cells.
This oxygen-poor
blood then travels
back to the right side
of the heart.
The oxygen-poor
blood needs to lose
the carbon dioxide and
pick up more oxygen.
How does it do this?
body’s
cells
Next, the right side
of the heart pumps
oxygen-poor blood
to the lungs.
lungs
In the lungs the blood
gets rid of the waste
carbon dioxide and
collects more oxygen.
Where does this
oxygen-rich blood
then travel to?
body’s
cells
The oxygen-rich
blood then returns
to the left side of the
heart.
lungs
This completes the
blood’s journey
around the body.
Why is the journey
of blood through the
circulatory system
called a double
circulation?
body’s
cells
During one complete
circuit of the body,
blood passes through
the heart twice.
lungs
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?
body’s
cells
Exterior heart structure
The heart pumps blood around the
circulatory system.
What is the heart made of?
muscle
tissue
The heart is made of muscle and keeps pumping blood
around your body, even when you are asleep!
What do the blood vessels on the outside of the heart do?
The heart is full of blood but also needs its own blood
supply so that the muscle can keep pumping.
muscle
tissue
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.
Interior heart structure
♥ 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.
right side
of the heart
left side
of the heart
Each section of the heart is called a chamber.
How many chambers are there?
4
The four chambers of the heart have special names:
♥ An upper chamber is called an atrium (plural atria).
right
atrium
left
atrium
right
ventricle
left
ventricle
♥ A lower chamber is called a ventricle.
The chambers of the heart have different
functions. blood to
blood to
the lungs
blood from
the body
the body
blood from
the lungs
♥ The atria collect blood that enters the heart.
♥ The ventricles pump blood out of the heart.
Describe double circulation
 The
two sides of the heart (left and right) are
separated by the septum
 Blood in the right side is deoxygenated (oxygenpoor)
 Blood in the left side is oxygenated (oxygen-rich)
 the right side of the heart is less muscular as the
blood is pumped to the nearby lungs

Blood is under less pressure
 The
left side of the heart is more muscular as the
blood is pumped to the rest of the body

Blood is under higher pressure
Arteries
Habits of the heart – take your pulse
 Carry
blood away from the heart
 Except for the pulmonary artery, transport
oxygenated blood
 Artery walls are thick and elastic so they can
stretch under the high pressure of blood

As the arteries stretch, they “pulse”
thick outer wall
thick inner layer
of muscle and
elastic fibres
narrow central
tube
Veins
 Carry
blood to the heart
 Except for the pulmonary vein, carry deoxygenated
blood
 Wider than arteries, with thinner walls

Blood under lower pressure
 Valves
prevent the back-flow
thin outer
of blood
wall
thin inner layer
of muscle and
elastic fibres
wide
central tube
Valves
vein valve
open
blood to
the heart
When blood flows along veins it
pushes past
the valves, which can
only open in one direction.
When valves go bad!!
backflow
prevented
vein valve
closed
If blood in a vein does flow
backwards,
it is trapped by
closed valves.
Varicose veins
Capillaries
 Capillaries
are the tiny blood vessels that carry a
blood supply to and from the body’s cells.
artery
 Capillaries
vein
are the only blood vessels where
substances can be exchanged between the
blood and body cells.
The heart beat
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.

Sequence of a
heart beat
The heart beat

When the heart muscles
are relaxed – diastole

Blood flows from veins into
atria
 When
the heart muscles
contract – systole


Atria contract first to pump
blood into ventricles (valve
between atrium and
ventricle opens)
Ventricles contract to pump
blood into the arteries
(forces valve to shut)
Normal blood pressure:
120 Systolic pressure
80 Diastolic pressure
Coronary heart
disease
 Use pp 106-107 in your text books to read about CHD.

Write notes to:
 Describe the nature of CHD
 State the possible causes of CHD

Describe some methods of preventing CHD
Pulse rate
 Read
“the heart and exercise” p 105 of your
textbook
 In pairs, compete the practical on p105 to
investigate the effect of exercise on pulse rate.



Stopwatches are available
Draw up a results table in your notebook to show
your resting heart rate compared to your HR after
completing the various activities
Explain your results (think about the purpose of
blood supply to your muscles)
Blood
 The
liquid part of the circulatory system
 Blood cells are suspended in plasma
 An adult human has about 5.5L of blood in their
body
The four
components of
blood
plasma
white blood cells and
platelets
red blood cells
 Blood
plasma carries three types of blood cells.
 They have different shapes and carry out different
functions.
red
blood cell
white
blood cell
platelet
Components
of blood
Micrographs of blood
Platelet
White blood
cell
Red blood
cell
Scanning electron micrograph of blood
Red blood cells
 The
most common type of blood cell.
 Made in the bone marrow
 Transport oxygen from the lungs to the body’s cells,
where it is used in respiration.
oxygen
A red blood cell has several features that help it do its
job:
It contains
haemoglobin,
a special pigment
that combines
with oxygen.
It has no nucleus, so
there is more space for
haemoglobin and so
more oxygen.
Disc-shaped, with
a dent on each side,
creates a large
surface area for gas
exchange.
A large surface area
compared to volume,
so oxygen is always
close to the surface.
 Another
important feature of a red blood cell is its
size.
 The diameter of a red blood cell is slightly bigger
than the average diameter of a capillary.
 This
forces the RBC to slow down as it passes through
a capillary.
 The surface of the RBC is exposed to the surface of
the capillary so gas exchange occur.
 Haemoglobin
is the special pigment in red blood
cells.
 At the lungs, oxygen diffuses into red blood cells
and combines with haemoglobin to form
oxyhaemoglobin
oxygen
+
haemoglobin
 This
oxyhaemoglobin
oxyhaemoglobin
is how red blood cells are able to bind to
oxygen and carry it in the blood.
 Oxyhaemoglobin makes red blood cells appear
bright red.
 Red
blood cells loaded with oxyhaemoglobin carry
oxygen from the lungs to the body’s cells.
 Here, oxyhaemoglobin changes back to
haemoglobin and oxygen is released.
oxyhaemoglobin
haemoglobin
+
oxygen
 Oxygen
is then able to diffuse into the body’s cells.
oxygen +
haemoglobin
haemoglobin
(not to scale)
oxygen +
haemoglobin
haemoglobin
oxyhaemoglobin
oxyhaemoglobin
oxyhaemoglobin
oxyhaemoglobin
(not to scale)
oxygen +
haemoglobin
haemoglobin
oxyhaemoglobin
oxyhaemoglobin
oxyhaemoglobin
oxyhaemoglobin
haemoglobin
haemoglobin
++ oxygen
oxygen
(not to scale)
oxygen +
haemoglobin
haemoglobin
oxyhaemoglobin
oxyhaemoglobin
oxyhaemoglobin
oxyhaemoglobin
haemoglobin
haemoglobin
++ oxygen
oxygen
(not to scale)
Red blood cells in an
alvelous
Red blood cells in a
capillary bed
White blood cells




The largest type of blood cell.
They have a large nucleus and can change their shape.
White blood cells protect the body from disease by fighting
invading microbes that can cause infection.
White blood cells can squeeze through the walls of capillaries.

Different types of white blood cells protect the body in different
ways:
 Phagocytes fight against infection by surrounding invading
microbes and then digesting them!

Lymphocytes produce antibodies to fight against infection.
White blood cell count
Doctors can check the number of white blood cells in a
person’s blood to find out if they are healthy or fighting
off an infection.
Healthy:
white blood cell
count is low
Unwell:
white blood cell
number is high
Platelets



Important for blood clotting.
platelet
Platelets are cell fragments that have broken off from other larger
cells.
They are much smaller than red and white blood cells and do not
have a nucleus.
1
Platelets help to make
tiny fibres that form a
net at the site of a cut.
3
The clot dries and
forms a scab which
protects the cut
while new skin grows.
2 Red blood cells
are trapped in this
net forming a blood
clot.
Why is it important
not to pick a scab?
Plasma
 Liquid
part of blood that
makes up 55% of blood
volume
 Water with lots of things
dissolved in it:




Nutrients: glucose, amino
acids, lipids, vitamins and
mineral ions
Wastes: carbon dioxide
and urea
Antibodies
Hormones: insulin,
adrenaline, glucagon
Which type of blood cell?
Multiple-choice quiz