The circulatory system transports blood throughout the body using blood vessels. Blood carries oxygen, nutrients, hormones and waste products as it circulates from the heart through arteries and veins, with an exchange of substances occurring between blood and body cells in capillaries. Some organisms have a single circulation where blood passes through the heart once, while mammals like humans have a double circulation with blood passing through the heart twice per circuit. Heart disease can be caused by factors like lack of exercise, poor diet, smoking and genetics, and treated through lifestyle changes, medication, procedures like angioplasty, or surgery. The lymphatic system works with the circulatory system to transport lymph and help fight infection.

1. The circulatory system
Our body’s public transport system

2. Our transport system
Blood
Blood cells Blood plasma
Red
Biconcave
No nucleus
haemoglobin White
Irregular
Contain nucleus
Some produce antibodies
Some swallow bacteria
Platelets
Cell fragments
Responsible for blood clotting
Contains: water,
CO2, Glucose,
amino acids, salts,
urea, hormones.
Lymphocyte Phagocyte

3. Blood vessels
Blood flow

4. Exchange of substances between blood &
body cells
Name the substances you expect to find at d & e.
Name the process by which each substance moves into/out of
blood.

5. Comparing blood vessels
feature artery Vein Capillary
Function
Wall thickness
Do the walls
contain elastic
fibers?
How wide are the
vessels?
Valves
Blood pressure
transport blood from transport blood from allows exchange
heart to all organs organs to heart of substances
Thickest thinner thinnest-1cell thick
Yes less no
Narrow widest narrowest
No yes no
Highest lowest lower

6. Single and double circulation.
 In some organisms such as fish blood is
pumped in one cycle that passes
through the gills and then to body
organs and back to the heart. This is
called a single circulation where blood
passes through the heart only once on a
complete circuit.
 The disadvantage of such a circulation
is blood is slowed down greatly by
passing through the very thin capillaries
of the gills.
 Other organisms such as reptiles, birds
and mammals have a double
circulatory system where blood
passes by the heart twice to complete
on one complete circuit of the body.
 Can you tell how is having a double
circulation better than a single
circulation?

9. Heart structure

10. Heart disease

11. Factors causing heart disease:
 1. lack of exercise
 2. diet rich in animal fat
(cholesterol).
 3. eating too much salt
 4. stress
 5. genetic factors
 6. smoking

12. Coronary heart Disease CHD
The coronary arteries have the important role of delivering oxygenated
blood containing glucose to the very active muscle cells of the heart.
Having narrow or blocked vessels may cause a heart attack and death
of heart muscle tissue making the heart weaker or even totally unable to
perform its job. Cholesterol builds up on the walls of an artery forming
plaque, which makes the wall of the artery uneven making blood clots
(thrombosis) more likely which will make the blood vessel even
narrower or totally blocked.

13. Coronary heart disease CHD
Heart disease can be
avoided and reversed in
some cases by making
changes to the life style:
 1. Stop smoking.
 2. Eat a diet low in
saturated fats,
cholesterol sugar and
salt.
 3. Exercise regularly.
 4. Avoid stress.

14. Treating CHD.
 For cases that cannot rely on
lifestyle changes alone; they
might:
 1. Given medication such as
Asprin and statins.
 2. Undergo angioplasty to
widen the narrowed or blocked
coronary arteries.
 3. Have a coronary by-pass
surgery, where a new blood
vessel replaces the damaged
vessel.
 4. Have a heart transplant
surgery where a heart from a
donor replaced the damaged

15. Monitoring the heart condition
 A stethoscope is used
to listen to the heart
sounds.
 A sphygmomanometer
is used to measure the
blood pressure.
 An electrocardiogram
is used to record the
heart’s activity producing
an ECG trace.

16. Getting back in rhythm
 The heart beats are controlled
by a group of muscle cells
called the pacemaker; that
sends electrical signals which
cause the contraction of the
heart muscles in the atrial walls
followed by the ventricular walls.
 The pacemaker adjusts the
heart beats during exercise to
increase the heart rate and
lowers the heart rate during
sleep.
 If a pacemaker is not working
well an artificial pacemaker is
placed in the person’s heart to
make the heart beat at a regular
pace
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17. Lymphatic system
It is a network of blind–
ended vessels filled with a
solution called lymph. It
contains nodes that act as a
“checkpoint areas” where
lymphocytes & phagocytes
are concentrated to handle
foreign microorganisms,
acting as a filter for tissue
fluid.
The liquid rejoins the
circulatory system at the
subclavian vein.
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18. The role of the lymphatic system
 It helps the circulation of
body fluids.
 It helps in the
absorption of fat
(through lacteals in villi).
 Lymphocytes are made
in lymph nodes.
 The lymph nodes form
part of the body’s
defence system.
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